weeds

September 13 2023

Group Update, September 2023

ashleyriver 4X4, annual survey, black billed gulls, black-billed gulls, black-fronted tern, management, research, Trapping, weeds, wrybill

One of the first indications of an imminent nesting season is the arrival of wrybills at the estuary – destined for not only the Ashley River, but other rivers to the south. This year they were first noted on 19 August and have occurred in flocks of up to 31. Amongst them have been 7 birds that we have banded up the river in the past – last year, the season before, or in the case of BWBW – quite a few years ago. Some of these have been seen several times, one (KOWY) was there for about a month.

We have counted only about 7 wrybills along the river so far, these have been in the usual nesting areas off Groyne 2 and Smarts. Nests have yet to be found.

Banded dotterel have been slow to arrive at the estuary and along the river. But on 11 September there were 8 in the area where they nested last year in the estuary east of the Kings Ave entrance and 5 at the Smarts area along the river. One of our new members has found 2 BD nests in the river up near the gorge.

Black-fronted terns won’t be nesting until early to mid-October, but they have been gathering in places along the river and where the river meets the estuary. A week ago, there were about 70 off the Swamp Road river entrance.

For several weeks black-billed gulls have been gathering, sometimes in numbers of around 500 – 600, just downstream from the Cones Road bridge. They don’t appear to be nesting as yet, and could well move on to somewhere new.

Preparations for the nesting season have included weed clearing, river entrance blocking and a rat detection dog effort against Norway rats.

Using funds provided by the Waimakariri Zone Committee and ARRG, in July we cleared 27ha of weeds using the tractor mounted ripper made and owned by Cresslands Contracting. Our first targets were high islands which had been nested on before, then other weedy islands, but also areas of quite thick weed – mainly lupin. The machine worked well on flat areas with lupin, but not so well where there were small gorse plants or where the ground was uneven. There was a significant flood on 23 July (394 cumecs at the gorge) which covered most of the fairway and also cleared a lot of weeds – weeds will not be an impediment to nesting this season. This flow was enough to change the layout of the river, with fewer braids and less shallow feeding habitat remaining, perhaps this will cause a reduction in bird numbers. Smaller floods will hopefully improve the habitat during the nesting season, but they may also wash away nests.

In early August, Leona Kirk of Wildlife Protection Services used her rat detection dogs along the south side of the river. The aim was to try and find and deal with Norway rat colonies before they could affect the birds. Norway rats are our most destructive predator. The most signs of rats were found on trap line F (westernmost line on the south bank), where the most Norway rats had been caught in the last year. The dogs indicated the presence of rats in a burrow which had been excavated into a muddy bank. This was dug out, but only went for a few metres and no rats were found. Evidence of rats (scent, tracks etc) was found out on the riverbed in several places – where the rats seem to have ventured after the flood in search of food. Trail cameras were placed at 3 of these sites, and rats were seen on photos.

We followed this up with a few hours of loader time (Cresslands) to try and dislodge them from piles of debris or burrows along banks, but none were found. We couldn’t use the loader in all the planned locations due to boggy conditions. Despite the lack of rats killed, we have learnt some valuable information. As suspected, Norway rats burrow into banks, especially muddy ones – but they also take possibly short-term refuge in debris piles. They do not appear to be present in large colonies along the river, and seem to move around quite a lot. This makes them more difficult to deal with than hoped for.

In the first few days of September most of the access points to the river were blocked off – in a very satisfactory joint venture between ARRG and the ECan Parks section (top image). We scout out locations to be blocked (this year with an ECan ranger) ECan provide and transport new blocks – and organize and pay for a digger to install them, and we supervise the installation. They will remain in place until February next year. This year 17 new blocks were needed (top image). In a few places banks were steepened up to deter 4wds. There are still many places where motorbikes can get out on the river.

There are several new trappers with river lines. Predator catch hit a new record in the August 2022 to July 2023 season. This was partly due to 102 extra traps funded by ECan and managed by Excell Biosecurity, and partly to the ongoing Ship rat boom. Catch rate increased in the estuary traps for the first year since we started trapping – in 2018.

The annual report is almost complete.

To mark the 100^th birthday of Forest and Bird, Bird of the Year is this year Bird of the Century. The black-fronted tern is a candidate, and the photograph they are using is of a bird from the Ashley. Please vote BFT.

Our annual bird count is on 18 November this year.

At the estuary –

Eleanor Gunby is carrying on with her MSc thesis work – with further funding provided by the Waimakairiri Zone Committee through ARRG.
This season there seems to be even more human disturbance. The Waimakariri District Council is reviewing the Northern Pegasus Bay Bylaw and will be asking for public submissions, probably from mid October to mid November. We would like to tighten rules around dogs and vehicle access.
As a result of ARRG advocacy, ECan is going to be doing some work on the Southern Black-backed Gull nests at the estuary. Along the spit, and probably along the western margin of the estuary, eggs will be broken and nests destroyed. Last season SBBG were responsible (along with disturbance) for the inability of BD to nest along the spit, and for the destruction of a white-fronted tern colony.
Bev Alexander is giving a talk on estuary birds for the Waimakariri Biodiversity Trust at the Waikuku Beach hall from 7pm on 13 September.

Grant Davey

11/9/23

February 20 2022

Group Update, February 2022

ashleyriver annual survey, black billed gulls, black-billed gulls, black-fronted tern, management, research, Trapping, weeds, wrybill

The last Update was written in August 2021, so much has happened since then. The main events have been our annual bird survey in November, and our monitoring of a full 2021-22 breeding season. It is these two activities which are key to determining whether we are succeeding in our mission of ‘protecting birds and their habitat in the Ashley River/Rakahuri’.

The birds

Annual survey. The 20 November Ashley-Rakahuri (A-R) survey attracted a record number of 23 people, who covered the 21km between the Okuku confluence and the SH1 bridge in 4 groups – most finishing by 1pm. The numbers of birds counted are shown in the figure above (prepared by Grant Davey).

This appears to show a recovering population, heading back towards the highest numbers of 2014. However, we are suspicious about this, as close observation on the river prior to the survey indicated far fewer birds. We think the explanation is connected to floods in the Waimakariri at the time of the survey, which caused birds to retreat to the A-R. Whatever the reason, there were record numbers of nearly all species. The total wrybill count was 30, higher than the previous record of 27 in 2019 (which was also a year when birds were being flooded out of the Waimakariri). Without this invasion, the low numbers of the last few years in the Ashley would almost certainly have continued. But it does show the importance of the A-R as a flood haven for birds washed out from the much bigger main divide-fed rivers.

Last year, our survey data since 2000 was sent for consideration by a national panel reviewing the NZ Threat Classification System. As they said in a ‘thank-you’ message, such long-term datasets are extremely valuable. From our data, they calculated that the numbers of black-fronted terns seen on the A-R have increased significantly, by an average of 5.4% per annum; wrybills have increased by 3.8%, and banded dotterels by 1.8% (although they have declined since 2015 – as seems to be the case nationally). Black-billed gull numbers have also increased markedly. We used to have a breeding colony only every 2-3 years, whereas they have turned up almost annually since 2016. We will never know exactly, but our management is likely to be behind these increases in bird numbers on the A-R.

The breeding season. Due to the record floods in May/June last year, the birds returned to find an almost weed-free A-R. Such disturbance to core aquatic insect food sources may have been a reason why the season got off to a slow start. But we ended up with 13 wrybill taking up territories – the previous highest being 10. Eight chicks fledged to give a productivity of 0.62. This is the most pairs and the second most fledglings on record, but productivity was below average. We located 96 black-fronted tern nests, but only 11 fledglings have been seen, mainly due to predation. Entire colonies were lost to rats, plus a flood did not help. Consequently, many nests would have been second attempts, some perhaps even third. Such fickle tern breeding has been par for the course over most years, and it is surprising that overall numbers have actually increased. For the first time since 2016, there was no large black-billed gull colony on (or close to) the main riverbed, but a large colony of many hundred nests formed (twice) at the estuary. The second effort was successful, with many hundreds of fledglings produced. Our other focus species (banded dotterels, pied stilts and South Island pied oystercatchers) appeared to have reasonable seasons, but too few nests were found to measure success. We plan to monitor them more closely next season. Plus we hope to engage a student to start monitoring bird breeding around the estuary (never done before).

Maintaining habitat

Weed invasion. This remains our greatest threat, as although the record May/June floods swept the riverbed clean, the weeds have rapidly returned. We have been meeting with ECan to discuss how we can remove weeds while they are small (with most yet to seed). The recent good February flood did more clearance, and we plan to clear much of the rest from favoured areas within the next 2 months. If successful this would be a major advance in management. Once the large operational clearances have been completed, we could well use volunteers to hand clear the gaps.

Gravel extraction. This is the main commercial activity undertaken on the river. Although gravel extraction can assist the birds by removing weeds, there are many examples which show that it can also create problems if not carried out properly. We are not happy with recent consent applications, and the history of compliance monitoring being carried out appropriately is not good. Plus, and perhaps most importantly, safety aspects associated with gravel extraction need improvement. These concerns have been pointed out to ECan, and it may be that, in order to bring about much needed changes, we have to go more public in the near future.

Flood control management. We fully agree that flood control should be the No. 1 goal, but we are concerned about how this is being carried out. All experts agree that in order to maintain the characteristic features of a braided river, it must be given room to move, but current management has resulted in excessive berm planting, which is leading to the A-R fairway becoming overly constricted. ECan has recently made environmental considerations a much higher priority for management, and we are to be involved in discussions to this end, so we are hopeful of changes in the right direction.

Predator trapping

This remains our major commitment in terms of personnel and operational hours involved – and continues all year round, both alongside the river and around the estuary. Currently there are 182 traps along the river and 102 at the estuary, serviced at least monthly by 26 volunteer trappers. In addition, during the season, there are around 60 traps (mostly run-through DOC150s) managed separately around breeding birds. As the discussion below indicates, even though the current trapping effort remains significant and important, we know we should be having a greater impact on predator numbers.

Trap catch. Alongside the river. Despite the consistent trapping effort, results show that the trap-catch rate has been static over recent years – at around 0.5 predators caught per 100 trap nights. Over the last 3 years, we have caught more than half the total number of predators since we began trapping in 2004. At that time, the major catch was hedgehogs. These still remain predominant, but have been joined in recent years by rats, which were rarely caught before 2016. Ship rats have been responsible for nearly all bird losses over the past season. It is interesting to note that stoats were slightly more common than weasels until around 2016, but have well outnumbered the former ever since.

Around the estuary. The composition of predators caught alongside the river is very different to that caught at the estuary. Compared to the river, the estuary has a higher percentage of rats (54% estuary; 37% river), stoats (14%; 6%) and weasels (22%; 14%), but a lower percentage of hedgehogs (6%; 34%) and feral cats (4%; 9%). The reasons for this are unknown. We have only been trapping around the estuary for 3 years, but it appears that the catch is decreasing over time. This could be due to our trapping, but it could also be because we have a much greater trap density than along the river

How effective are traps? As mentioned in the August update, we have long suspected that many predators visiting trap sites do not get caught. A trail camera/trap project undertaken a year ago by a student, Quill Yates, confirmed this. Almost 20,000 images were analysed. The main finding was that only 8.3% of predator visits resulted in successful catches. The percentage caught / visit for feral cats, rats and hedgehogs were 2%, 22% and 23% respectively. The traps had visits from 50 cats, and Quill went to some trouble to identify 20 different individuals. Only a single cat was caught, even though on 35% of visits, they put their heads into the Timms trap openings but did not trigger them. Too few mustelids (ferrets, stoats and weasels) were caught to allow for any analyses to be done.

Trapping review. A year ago, ECan agreed to fund a review of our trapping strategy, including the possibility of doubling our trap numbers by installing a double line alongside the river. A contractor has just completed this review which should be available for reading in the near future.

Public relations and human disturbance on the riverbed

We continue to make sure the public are well informed – via media articles, presentations and talks, displays, Facebook and website. How we manage the latter is currently being reviewed. It is well worth listening to our monthly interviews on the local CompassFM radio station. A large new interpretation panel will be erected by the Cones Road bridge picnic area in the near future. As in previous seasons, 4WD access ways which were blocked in September, have just been cleared. There is little doubt that this has resulted in significantly less vehicle disturbance during the past breeding season.

Finances

The Group is always closely following its accounts and budget situation – and generally our finances are in good shape. We are now mostly self-funded for our day-to-day existence, with monies coming from donations, our trap making and selling, and sponsorship via Karikaas Natural Dairy Products Ltd cheese sales. Funds for larger special projects usually come from ECan.

Reports

For over a year, ECan has been drafting a long-term management plan for the Ashley-Rakahuri River. This will be available to us within the next 2 months, and should shape where we head in the future. The annual report for 2020-21 has been completed and is now available. Internally, there have been a number of other reports written, mainly by Grant Davey.

Group structure and meetings

In addition to the normal committee hierarchy of chair, secretary and treasurer, we have created three management teams – operations, communication and administration. It was felt that such a structure will lead to less work required by any one individual. At our last AGM, the Group chair, Nick Ledgard, stepped down after 20 years in that position, to be replaced by Sue Mardon. More recently, our Secretary, Joan Miles, also retired after 20 years of service to the Group. In the near future, we plan to have a SWOT (strengths, weaknesses, opportunities, threats) gathering, in order to review our composition and where we think we should be headed.

As usual, many thanks to all our volunteers for the time taken to support our cause.

Sue Mardon

Chair, ARRG

October 7 2021

AGM: Outgoing Chair Report

ashleyriver black billed gulls, black-billed gulls, black-fronted tern, floods, management, Predators, research, Trapping, weeds, wrybill AGM

by Nick Ledgard, outgoing ARRG Chair

Welcome everyone to this AGM. The Ashley-Rakahuri Rivercare Group was formed in 1999, and became an Incorporated Society in 2005. My report is usually an adaptation of the summary from our annual report for the last season – in this case for 2020-21. That is contained in this document – written by myself and Grant Davey. But this year, I am going to depart from that format, as this will be my last report as Chair of this Group – after 18 years in that position.

Have we succeeded? Looking back over that time, one has to ponder over what has been achieved, and that of course has to be measured against the Group’s objective. Our mission statement is ‘To protect birds and their habitat in the Ashley Rakahuri River, while recognising essential river control works and sympathetic recreational uses’. Therefore our primary objective is to restore, or at least maintain, the indigenous bird species which breed on the river – the wrybill, black-fronted tern (BFT), black-billed gull (BBG), banded dotterel, pied stilt, and South Island pied oystercatcher – and hopefully in the future, the black stilt. In this respect, if I was an outside interviewer, my first question would be: ‘Well, after over 20 years, (with you heading the Group for 18 of those), have you succeeded?’

Monitoring. One cannot answer that question without good monitoring, and we have done a reasonable job on that score. We use two measures. One is annual population or number counts via our annual survey in mid-November, and the other is breeding success, measured by annual productivity – which is number of fledged chicks per nesting pair of birds. The ways in which we have measured these are far from perfect, but as we have done population surveys since 2001 and productivity monitoring since 2005, we can put some certainty on trends.

Population or number counts. This is what the data show us. Looks great up to 2015, but the decline since then is not attractive. The high figure in 2019 is an anomaly caused almost certainly by the Waimakariri River being in constant flood and our river acting as a refuge. We hoped it was also a sign of bird numbers returning to former levels, but the count for the following year (2020) indicates that not to be the case. So, all this graph really tells us is that we are at least maintaining bird numbers during this century. Needless to say, we sincerely hope that this year’s survey (November 20) sees a good increase in counts. But, we are only 6 weeks away from that date, and so far this season, numbers do not look encouraging. This could well be due to the record floods of late May / mid June having shaken up the core aquatic insect food supply, which is taking more time than usual to get up to speed. We will soon see.

Breeding success – productivity and chicks fledging. This is much harder to estimate, as chicks are hard to follow through to fledging. However, we have attempted to do so with wrybill, BFT and BBG since 2004. The results are as follows. Once again, they don’t appear to show a significant improvement over time – possibly because survival between egg hatching and chick fledging has not been overly threatened. However, if one compares the number of chicks fledged in the first 6 years of monitoring (2004-2009) and the last 6 (2015-2020), one finds that wrybill have increased from 3.5 to 5.9, and BBG from 75 to 394, whilst BFT have not changed much – from 16 down to 14. So, it appears that we are enabling more wrybill and gull chicks to get into the air, but not tern chicks. Probably the best take-home message of all about this is the importance of long-term monitoring – we may be the only volunteer group with such impressive records.

So, I look back over the years, and my term as chair, and reflect on not as good an outcome as I would have hoped. But I am aware of population and breeding monitoring on other braided rivers, and in comparison to those, our results generally look a lot more positive, Plus, I am an optimist, and I am sure the future will show an improvement, and that our efforts to date to have been vital in maintaining a base to attain that.

Weeds. In the first graph I held up, apart from the bird numbers, we follow the rise and fall of bare gravel area – thanks to the mapping skills of Grant. When I first saw this and the close correlation between bird numbers and gravel area, I immediately went back to Grant and asked him to check his figures. After 40 years in research, I had never seen such a close correlation between an effect and a likely cause. But it is a real one, which underlines the importance of weeds in retaining bird numbers on braided rivers. Hence, I see the control of weeds as our greatest challenge in the future if we are to attain our mission statement. The record floods of May/June have swept the riverbed as clear as I have ever seen it. But by Christmas there will be a green tinge to most of it, and if nothing is done (coupled with the likely absence of another record flood), we will be back to the autumn 2017 weed infested situation within a few years. Needless to say, we are thinking hard how to make use of the unique weed control opportunity which the floods have presented us. And we cannot just sit around and discuss it – any cost-effective solution will have to be applied within a year, while the weeds are small, starting after February once the birds have finished their breeding season.

Predator control. This is by far the biggest single activity undertaken by the Group. At present we have 236 traps alongside the river, maintained by 18 volunteer trappers, while around the estuary we have another 129 traps maintained by 8 trappers. This gives a grand total of 365 traps and 26 trappers checking them every few weeks – a very impressive effort. Once again we have to ask – has this been successful? According to our records, we have caught 3353 predators since 2004, and without doubt have saved 100s of birds from gruesome ends. If one looks at trap-catch over time (numbers caught per 100 trap-nights), we averaged 1.3 predators trapped annually for our first 6 years (2004-2009), whereas for the last 6 years (2015-2020) the figure is around 0.5. This is comforting, but once again the long-term picture appears to be one of maintenance of what we would like to say are ‘low’ numbers, rather than one of a steady decline towards elimination. Hopefully this will change for the better soon, as last week we met with a contractor who is going to write a plan for almost doubling our trap numbers alongside the river (paid for by ECan).

River management. As most of you will know, we have had cause to contest how the river has been managed in the past – with too much emphasis on flood control at the expense of environmental values. A braided river must always have room to move. Plus we have also not been happy with the some of the results arising from commercial gravel extraction. Grant has led that discussion with ECan, and I am confident that we are seeing light at the end of the tunnel.

Awareness / education. I consider that we have been very successful in improving awareness at the public, education and institutional decision-making level. Most people are now aware of the birds on the river and how we are assisting their improved well-being and long-term survival. This is due to multiple awareness activities – our website and Facebook postings, displays, media and magazine articles, interviews, talks and Ppt presentations to councils, schools and community / interest groups. In this annual report we list 45 promotional activities undertaken in the last year.

So, I look back over the last 20 years with a degree of satisfaction relative to achieving our mission, plus many happy memories of the process followed to achieve that.

Thanks. Last but never least, I conclude with thanks to all members of the Group for the work they have put in over my time. There are far too many to name individually. But there are some I must mention: Joan Miles for her work as Secretary, Sue Mardon for her excellent work as Treasurer; and in the trapping arena, Peter Whitehead and Geoff Swailes and the impressive volunteer trapping team. Then there is Grant Davey with his mapping and record-keeping skills. Any volunteer group can only utilise the skills that are present within their membership, and Grant has significantly enabled us to look far more professional than we actually are. When I started in the early years of this century, the words ‘social media’ were little used, but they are absolutely vital in holding one’s own today. So thanks to Sonny Whitelaw and Steve Attwood for looking after our website and Facebook outlets. Then there is our one-and-only sponsor, Karikaas Dairy Products Ltd. Most importantly ongoing thanks are always due to ECan and their Regional Park staff, the Waimakariri DC and DOC. We might be the body which makes passionate pleas on behalf of the public, but without their professional support it would be very hard to make meaningful progress.

August 23 2021

Group Update, August 2021

ashleyriver 4X4, annual survey, black billed gulls, black-billed gulls, black-fronted tern, floods, management, Predators, research, Trapping, Trapping, weeds, wrybill

by Nick Ledgard, ARRG Chair

The last Update was written earlier this year in January, so a fair bit of water has gone under the bridge since then. Quite literally actually, as the most significant happening affecting our local river over the last 6 months has been the record floods of late May and mid June.

Down on the river. The floods not only cleared the riverbed of virtually all weeds, but also ate into the margin of the vegetated berm which lies between the open fairway and the marginal banks. This has widened the fairway in places, but it may well be less braided than before. Despite the floods, the berm remains considerably wider than it was a few decades ago, and as stated publicly many times recently, a braided river must have ‘room to move’ in order to maintain the braided riverbed habitat which the birds need for successful breeding and feeding. Although we now have a ‘weed-free / clean slate’ riverbed, the future challenge is how to keep it that way.

Bird movement. After February, our core indigenous breeding bird species (wrybill, black-fronted tern (BFT), black-billed gull (BBG), banded dotterel (BD), pied stilt and S. Is pied oystercatcher) move out to warmer winter locations. Most retreat to the coast and the northern N. Island, whilst some of the banded dotterels cross the Tasman Sea to Australia. Over winter, only a handful of other species, including a few BFT, remain on the river. We have good records of these, as some sections of the riverbed are walked at least monthly by Grant Davey and myself.

Right now, the breeding birds are starting to return. The first wrybill was seen on August 16, and we can expect to find nests from around mid-September. Small numbers of BD, BBG and BFT have also been seen, and some BD may be nesting as they are usually the first to start. Nesting colonies of the gulls and terns are unlikely to be established before mid-October. The May/June floods mean that there are many weed-free sites available for breeding, but that major disruption which was followed by a number of other high flow events may result in a slower than usual return of core foods – aquatic insects and small fish.

Maintaining habitat. Weed invasion remains our greatest threat, as although the record May/June floods swept the riverbed clean, the weeds will rapidly return. Initially, they will be small and more readily removed, so we have new opportunities for sorting out the cost-effective means of controlling them. The riverbed is owned by ECan and understandably, the prime aim of past management has been on flood control. This has sometimes been at the expense of conservation values, such as bird habitat. Hence, over the last year, we have had many discussions about shifting the management focus more towards environmental considerations.

Gravel extraction. This is the main commercial activity undertaken on the river. Although such activity can assist the birds by removing weeds, there are many examples which show that it can also create problems if not carried out properly. In our discussions, we have pointed these out to ECan, who are keen to correct consent deficiencies and improve their oversight. They are very aware that we spend more time on the riverbed than virtually anyone else, and so can act as watchdogs. Gravel extraction has been considerable (some would say excessive) over recent years. It is likely to become more restricted in the near future, as despite the recent floods moving masses of gravel down-river, very little of this is ‘new’ ie., originating from catchment headwaters.

Predator trapping. This remains our major commitment in terms of personnel and operational hours involved – and continues all year round, both alongside the river and around the estuary. Over the last year there have been on average 236 traps along the river and 129 at the estuary, serviced at least monthly by 26 volunteer trappers. Nearly 100 traps were lost to the May/June floods, but thanks to generous cash donations and supply of materials, the majority of those have now been replaced. We are particularly grateful to the Mens Shed at Rymans Healthcare village who have made nearly all the replacement DOC200 boxes.

Trap catch. Over the past 2 years, we have trapped almost 1000 predators, with the dominant species being hedgehogs and rats. However, despite the consistent trapping effort, results show that the trap-catch rate has been static over recent years – at around 0.5 predators caught per 100 trap nights. The composition of predators caught alongside the river was very different to that caught at the estuary. Compared to the river, the estuary had a higher percentage of rats (53% estuary; 35% river), stoats (16%; 6%) and weasels (18%; 11%), but a lower percentage of hedgehogs (9%; 38%) and feral cats (5%; 10%). The reasons for this are unknown.

How effective are traps? We have long suspected that many predators visiting trap sites do not get caught. In order to look more closely at this, we set up a project for a student, Quill Yates. He investigated predator visits and catches over a 2-month period last autumn. Trail cameras were set up at three sites where three trap types were placed alongside each other. Almost 20,000 images were analysed. The main finding was that only 8.3% of predator visits resulted in successful catches. The percentage caught / visit for feral cats, rats and hedgehogs were 2%, 22% and 22% respectively. Too few mustelids (ferrets, stoats and weasels) were caught to allow for any analyses to be done. A detailed report is being written, which will contain recommendations as to how the number of trap-catches might be improved.

Trapping review. A year ago, ECan agreed to fund a review of our trapping strategy, including the possibility of doubling our trap numbers by installing a double line alongside the river. A contractor has been approached to undertake the review.

Human disturbance. We continue to make sure the public are well informed – via media articles, presentations and talks, displays, and our website and Facebook page. In the 2020-21 year, there were 39 different promotion activities undertaken. Earlier this month, all 4WD access ways were mapped, and as in previous years, these will be blocked during the breeding season (September to the end of January).

Finances. The Group is always closely following its accounts and budget situation – and generally, our finances are in good shape. We are now mostly self-funded for our day-to-day existence, with monies coming from donations, our trap making and selling, and sponsorship via Karikaas Natural Dairy Products Ltd cheese sales. Funds for larger special projects usually come from ECan.

Reports. For over a year, ECan has been drafting a long-term management plan for the Ashley-Rakahuri River. This will recommend how we carry on into the future. It is hoped to be able to read this report in the near future. The annual report for 2020-21 will be completed within the next month. This, and a number of internal reports (referenced in the annual report), are written by Grant Davey and myself.

Group structure and meetings. In addition to the normal committee hierarchy of chair, secretary and treasurer, it was agreed in June to create three management teams – operations, communication and administration. It was felt that such a structure will lead to less work required by any one individual. The teams will be confirmed at the 2021 AGM on October 7, together with the member(s) to lead each of them. Our 8-person Management Committee continues to meet regularly.

Finally, this will be the last Update that I write as Chairman. After 18 years in this position, it is time to hand over to someone else.

As usual, many thanks to all our volunteers for the time taken to support our cause.

Nick Ledgard
Chair, ARRG

June 1 2021

May flooding

ashleyriver floods, Trapping, weeds

Ashley Rakahuri River flood 30 May 2021

Left: 4.00pm 29 May. Water flow 4 cumecs.

Right: 4.00pm 30 May. Water flow 966 cumecs.

Photos: Nick Ledgard

June 01

Photos – Grant Davey

Looking upstream from approximately the downstream end of what used to be the Railway island – only a few small islands poking out of the water, bare of weeds. The layout of the river here might be quite different when flows drop. And the effects of gravel extraction look likely to be wiped out – this had diverted at least 2/3 of the flow to the south of the island.

Looking downstream to the “Golf Links” island – this seems to have lost quite a bit of area – it is an island which we have wanted gone, it has mature weed and trees. Unfortunately the river is definitely not going to be going around it.

Looking upstream to the railway bridge. The awful heavily vegetated island here has lost a lot of area.

Looking over the railway bridge to the Cones Road bridge. Again lots of vegetated island area gone.

The small stopbank and trees along the edge of the area north of the Railway island. This shows how effective those willows which grow up from trunks laid along the edge of the berm are – breached in only one place, but the trees remain.

Just downstream from here, past where they had stopped doing this, the river did break through quite a high natural bank. I have/had a trap in the willows just past that bare gravel. I didn’t think this was a spot in danger. Two other traps just upstream from this photo, which I also didn’t think were at risk, had been washed a few metres and filled with sand. Further downstream I rescued a few traps, before the flood, which would definitely have gone.

We are not going to have to clear weeds this year, with the possible exception of a few willows. There doesn’t look to be a massive amount of driftweed around either. The higher islands and the berm, as expected, have attracted a lot of sand – so weeds will probably grow rapidly again. But from what you can see of the lower islands, they seem very gravelly which will be good for nesting and worse for weeds.

Once the river is back to 10 or 15 cumecs I’ll drone photograph between Cones Rd and SH1 to properly see what has happened.

– Grant Davey

January 17 2021

Group update Jan 2021

ashleyriver 4X4, management, research, Trapping, weeds, wrybill

Down on the river

The main gauge of our success in looking after the indigenous birds on the river comes from our annual surveys of species numbers. This season, the survey took place on November 21, and is well reported in Grant Davey’s report (2020 Ashley-Rakahuri Annual Bird Survey). The total of wrybill, banded dotterels (BD), black-fronted terns (BFT), pied stilts (PS) and S. Is pied oystercatchers (SIPO) was 376 compared with 1004 last year and 461 in 2018. This was the third equal worst year on record (along with 2002) for these species – with the worst year being 2001 (285 birds). Before thinking ‘all is lost – we’ve failed’, consider this. Numbers plummeted after 2014 due to lack of large floods and a major expansion of invasive weeds. The 1-in-10 year flood of July 2017 brought the weed situation back to above the 2014 level and we thought the high 2020 survey figures indicated a great recovery. However, we now know that the exceptional bird numbers of that year were without doubt strongly influenced by floods in the Waimakariri forcing birds to move elsewhere. Right now the weeds are again advancing vigorously, so until we win that battle (see ‘Loss of habitat’ below) the bird numbers are likely to remain in the recovery phase. On the positive side, black-billed gull (BBG) Sept 21 survey numbers were 1820 (this species is not included in the above figures as a single colony can distort all-species comparisons), the second highest on record, and at the Smarts site BBG numbers had risen to 2846 a month later. Until relatively recently we had a BBG colony about every second year, but since 2016 a reasonable local colony has been an annual feature. At the time of writing, BBG numbers at the Smarts site (around 4ha) are 1780, of which around 1280 are flying juveniles. This would be one of our best ever BBG fledging results. The island site was cleared of weeds by a Taggart Earthmoving shingle extraction operation over the 2020 winter, and in addition to the large BBG colony, has attracted breeding BFTs, BDs, PSs, SIPOs and a single wrybill pair. As such, the site represents a vision of what bird life on the river can be, and this could certainly be improved further, plus hopefully replicated elsewhere (see below). At least 8 wrybill pairs took up territories over the season, which is the same as 2 years ago, and only a couple less than last season. Most of these hatched and fledged chicks. The species which remains of most concern is the BFT. Survey numbers were the fourth lowest on record, and their breeding success has once again been poor. Small colonies established to the nest/egg stage at 4 locations, but only the one at Smarts progressed to hatching chicks. Our monitoring of the Smarts colony this season has been mainly undertaken by Grant Davey, who regularly checks nests and traps in addition to aerial counts using our drone. The Group is extremely fortunate to have access to Grant’s data gathering and processing skills. I doubt if any other similar conservation entity in the country collects and publically presents such detailed results with such accuracy, clarity and promptness. For some weeks, Grant was greatly assisted by an ECan student intern, Matt Kim, who enjoyed spending hours observing the birds from our hide on the north bank of the river.

Loss of habitat

This remains our biggest challenge, and influences bird populations the most. The major concern is the rapid invasion of weeds – mainly lupins, gorse, broom, blackberry and willow, plus a range of grasses and other herbaceous species. The Smarts site, where bird breeding has been good, is a good example of this problem. It was virtually clear of weeds in September, but is now well covered in a new crop of seedlings. Weed invasion not only ruins bird breeding sites, but also smothers important shallow water/shingle margins where most feeding occurs. Nothing other than artificial clearing can be guaranteed to change this, as we cannot depend on natural floods. Last winter we cleared over 40 ha, mainly with a custom-built tractor-mounted undercutter. This coming winter we must do more of the same at selected sites which birds favour for breeding and feeding. Loss of open braided river habitat has also occurred as the berm zone (there to protect the stopbank) has expanded out into the open fairway – where birds feed and breed. As clearly stated in our 2019-20 annual report, over 50% of the fairway has been lost since 1942, and it continues to shrink to the present day. Excessive shingle extraction does not help to retain braids as it causes deepening and channelling of flow pathways. Discussions are underway with river engineers as to how this past management can be amended to enhance the ‘natural’ braided river character and extent of the Ashley-Rakahuri river. All this is part of a long-term planning process funded by ECan, and promised for consultation in the near future.

Trapping

This is by far our major commitment in terms of personnel involved and operational hours – and continues all year round, both alongside the river and around the estuary. There is a total of just under 400 traps out there, serviced at least monthly by 25 volunteer trappers. Since July 1, 2020, trap-catch figures alongside the river read 10 cats, 63 hedgehogs, 21 weasels, 8 stoats, 1 ferret, 8 rats, 18 ship rats and 25 Norway rats. Whilst at the estuary – 2 cats, 3 hedgehogs, 15 weasels, 17 stoats, 0 ferrets, 10 ship rats and 13 Norway rats. Last season, our large BBG colony at the Railway site suffered major predation by rats and harrier hawks. This year, only 2 Norway rats and a mouse have been trapped on Smarts island (compared to about 15 rats and a stoat last year), and raids by harrier hawks appear to have been minimal. The latter could well be due to scarecrows erected close to the colony. On December 11, a trappers BBQ was hosted at the DOC offices, attracting over 30 participants.

Human disturbance

The main way to reduce this is by making sure the public are well informed – via media articles, presentations and talks, displays, and our website and Facebook page. We now have a Promotions / Communications strategy, drawn up by professional advocacy member, Steve Attwood, and implementing that is a newly appointed Promotions Officer, Joan Miles. Our awareness efforts must be working, as compared to the past, this season has seen far fewer people and vehicle intrusions out onto the riverbed.

Visitors

Apart from talking to groups, making presentations and manning displays, we accompany visitors to see what is actually happening on the river. Over the season, we have had visits by those who have gifted donations, ECan engineers and riverbed staff, the Waimakariri Zone committee, an Orari Rivercare Group rep, a TVNZ crew and our Mayor, Dan Gordon. All appear impressed by what they see, and are very supportive for the continuation of our efforts.

Finances

Meetings

Our 8-person Management Committee met on December 1, followed by a general meeting on December 3. The MC will meet next before the end of this month. Please mark Thursday, March 18 on your calendar for our next General meeting – starting at 7pm at the DOC offices on River Road.

As usual, many thanks to all our volunteers for the time taken to support our cause.

Nick Ledgard

Chair, ARRG

October 8 2020

Creating bird habitat

ashleyriver management, weeds, wrybill

Title image: prior to the bird breeding season, commercial shingle extraction in the Ashley-Rakahuri river has cleared away weeds, and started to dig the channel which will create an island where the tractor is working. The tractor-mounted undercutter is making the site more attractive for bird breeding by roughing up the shingle surface.

Ashley-Rakahuri Riverbed Group members, Grant Davey and I, have just returned from the local riverbed, where the breeding season for indigenous species such as the ngutupare wrybill and pohowaru banded dotterel has been underway for about a month. We visited a site where much effort has gone into creating a desirable habitat for bird breeding.

Over the winter, prior to the breeding season, a local company, Taggarts Earthmoving Ltd, had extracted shingle from this site. Before they left, they made sure all weeds were removed, as it is well known that most braided river birds must have clean, weed-free shingle on which to nest. And over recent years there has not been the cleansing floods of sufficient size to clear away the increasingly invasive lupins, broom, gorse and blackberry. To complement this removal of the densest weeds, the Group has helped to develop a tractor-mounted undercutter to clear weeds from selected stretches of the river. Not only does the machine uproot weeds, but it creates the loose, coarse shingle surface most favoured by the birds. Our studies have shown that compacted or sandy surfaces are not so attractive to them.

Last August, we used the machine to clear almost 40ha of riverbed. Plus we got Taggarts to channel water across the tail end of their extraction site in order to create an island, which predators would find more difficult to access. However, as the old proverb says ‘one can take a horse to water, but one cannot force it to drink’. It is the same with the birds, one can create what one considers to be desirable nesting sites, but there is no guarantee that they will use them. Past experience has endorsed that.

But, this morning we observed the hoped-for and long-awaited results of our habitat creation endeavours. This is the reason why I sit here in front of my keyboard at home with a wider smile than usual.

As we waded across to the island earlier today, we noticed a movement amongst the stones. It was a female wrybill scuttling away through the stones, the give-away that there must be a nest nearby. So we retreated a short distance, and sure enough she soon came scuttling back and quickly settled down some 40m away. We waited a couple of minutes, taking careful note of the rock shapes and shades adjacent to where she was sitting. We did this, as seeing a wrybill settle on a nest is one thing – actually finding the nest is another. It is just a small-stone lined depression in the shingle and the eggs are the same colour as the grey-wacke rocks surrounding it. But find it we did, and while the adult bird gave us a broken-wing ‘distraction display’ just a few meters from us, Grant used his field tablet to photograph and GPS the nest location.

The island is finished and Group member, Grant Davey, is using his field tablet to photograph and GPS the nest of a wrybill pair which have chosen to breed in this deliberately prepared site. Their nest is almost precisely where the tractor was working (6 weeks earlier) in the photo at the top of this post.

As we backed off, she quickly returned to shuffle down onto her eggs, appearing so relaxed that Grant crawled forward to take a few close-ups with his point-and-shoot camera. Within barely 10 minutes of first seeing the bird we were happily on our way back to the wagon for the drive home.

Nick Ledgard

Grant taking a close-up photo of the female wrybill on her nest. Some birds are not disturbed by such intimacy, whilst others will disappear when one is still 50m away.

September 20 2020

Group update

ashleyriver 4X4, management, research, Trapping, weeds, wrybill

First of all, apologies for the lack of updates this year. In fact, there have been none, as the last was in December, 2019.

Down on the river

The last season was a good one for bird numbers, as nearly all species were present in record numbers. Breeding results were variable. Up to 10 wrybill pairs nested, raising 8 chicks, and for the first time since 2000 there were two black-billed gull (BBG) colonies containing over 2000 nests. There was also a record number of breeding black-fronted terns (BFT – 111 nests). But fledging results from both species was lower than the long-term average. All the details are in the 2019-20 annual report – due out before the end of this month. The start of this new season has seen the normal variable beginning. All the species are present, although so far only 2 wrybill pairs. The nests of both have been found, but one set of eggs has rather mysteriously disappeared, and the other is in a very vulnerable site. Good numbers of BFT and BBG have been seen, but they have yet to settle on nesting sites. Nests of banded dotterels and oystercatchers have been found, while pied stilts are again in good numbers. But it is still early in the season, so much will change. Once things have settled, we will arrange twilight visits to see the most accessible birds.

Trapping

This is by far our major commitment and continues all year round, both alongside the river and around the estuary. There is a total of just under 400 traps out there, serviced at least monthly by 25 volunteer trappers. Rats remain the most common catch, followed by hedgehogs, weasels, stoats and feral cats – with numbers of the last mentioned being greater over winter. For the first time we have been deploying bait stations to try to reduce rats before the breeding season starts, as they were a major issue at the big colonies last season. As were harrier hawks, which we will try to deter using scarecrows. Another source of adult bird losses last season was power line strikes. This season we will seek volunteers to check under lines, so that we have the figures to support an approach to power transmission companies.

Weeds

Weed invasion is arguably our major ‘new’ challenge. Between 2014 and early 2017 there was a significant decline in bird numbers caused by weed invasion and the loss of clear gravel breeding areas, before large floods over the 2017 winter increased clean shingle areas from around 30ha to over 250ha. However, these clear areas are now being reinvaded. As we cannot rely on good floods, around 35 ha was cleared in August by a locally developed tractor-mounted undercutter developed by Cresslands Contracting on Tulls Road. An Iranian PhD student, Sanaz Safavian, continues her studies of weed invasion successions on the riverbed at the Tulls site. Over recent times, the Group has become concerned about management leading to an ever-widening berm zone, which limits ‘room for the river to move’ and leads to loss of the ‘normal’ braided riverbed habitat essential for the long-term survival of riverbed birds. This matter is currently being discussed with ECan.

Human disturbance

The main way to reduce this is by making sure the public are well informed. We do this by all sorts of means, and the annual report’s activity list contains almost 50 entries – mainly articles, interviews, presentations, displays, our website, Facebook page and video. In order to improve awareness further, at the next meeting (see below) we will be proposing the acceptance of a Promotions / Communications strategy, drawn up by professional advocacy member, Steve Attwood. More directly, we annually assist ECan to block off the major vehicle access-ways for the period between September and February . This was completed during August, with signs strategically placed explaining why. Talking signs, a professionally designed interpretation panel will soon appear at the Cones road bridge picnic area.

Finances

The Group’s finances are in good shape. We are now mostly self-funded for our day-to-day existence, with finances coming from a trap making and selling project (197 traps made and 116 sold in 2019-20), donations and sponsorship via Karikaas Natural Dairy Products Ltd cheese sales. Grants for larger special projects, such as the recent 35ha of weed clearing, come from ECan.

Meetings

The COVID situation has allowed us only one general meeting this year – although our 8-person Management Committee has met on five occasions. So, please mark Thursday, October 8 on your calendar for our AGM, followed by a General Meeting. This starts at 7.30pm at the DOC offices on River Road.

As usual, many thanks to all our volunteers for the time taken to support our cause.

– Nick Ledgard, Chairperson

August 5 2020

Weed Removal Report

ashleyriver management, research, weeds

Background

Shorebirds breeding on braided rivers require clear shingle on which to nest. Over recent years the incidence of woody weeds has increased significantly on the Ashley-Rakahuri (AR) river. It is estimated that the area of clear shingle in the core bird breeding stretch of the river (21km between the Okuku river junction and the SH1 bridge) dropped from around 200 ha in 2014 to about 30 ha by January 2017. Subsequent major floods in 2017 increased this area to around 250ha, but maintenance of cleared areas will forever be a major challenge. To this end, a pilot trial using a bulldozer and rippers was carried out in July 2018. Its aim was to simulate a riverbed ripping technique which has been used for maintaining open bird breeding habitat within braided rivers in Hawkes Bay. Last year (2019) a customised ripper mounted behind a farm tractor was used. Reports on both the 2018 and 2019 work were written for ECan and DOC.

This report covers continued weed removal using the tractor-mounted machine in July, 2020. ARRG is most grateful for this weed clearance work being funded by ECan.

The full report is available here.

June 11 2020

Aspects of the Ashley Weed Problem

ashleyriver black billed gulls, black-billed gulls, black-fronted tern, management, research, weeds, wrybill

It is well established that birds that breed on braided rivers require bare gravel for their nests, and for many years members of the ARRG have understood that weeds pose a major threat to birds nesting on the Ashley. Exactly when weeds became a threat on the river is uncertain, but from the memories of various people, the fairway was essentially weed-free in the 1970s. Historic air photos have recently been obtained and will help in clarifying this. Efforts to clear weeds have been made since at least 2004 – these are documented in the full report.

Unfortunately, this has met with only mixed success and for some time weed pulling was done as a team building exercise rather than with real hopes of creating significant nesting habitat. Some years little or no weed clearing was done because floods had created plenty of bare gravel.

In early 2017 work was done that appeared to show that areas of past gravel extraction were preferred by nesting birds – however this needs to be revisited in more detail. Also, at this time areas of bare gravel were measured from air photos and satellite imagery for the length of the river, there appeared to be a strong correlation between bird numbers in the annual (November) surveys and bare gravel area. This work has led to further efforts to clear weeds. The outcome of that and the relationship between weeds and bird nesting success plus the future prospects are now available in this report.