Predators – Page 2

February 27 2019

Black-billed gull colony update February 2019

ashleyriver black-billed gulls, Predators

The gulls have finally left the Ashley/Rakahuri River after more than 3 ultimately successful months. They first attempted nesting just below State Highway 1 in mid-November, got washed out on 26 November, and were already building new nests 5km upstream by 1 December. This was after an earlier attempt to nest on the Waimakariri riverbed had been foiled by floods.

When the birds had moved far enough away from the nesting area to avoid disturbance, a count was made of nests by members of the ARRG. This was quite difficult to do as in several places there were as many as 6 per square metre. A total of 768 nests were counted, not all of these would have been used. A total of 22 dead chicks were seen in the nesting and creche areas – presumably this was due to natural causes.

The first chicks had hatched by 30 December and they soon moved off the nest area to a creche at the river’s edge 50m to the north. Chicks are hard to count, but efforts in late January and early February resulted in totals of 500 and 450. By 5 February all the gulls had moved to a new creche site 300m to the west. By this stage, most of the chicks had fledged and would have flown there. However, there were several that couldn’t fly, these were presumably herded there by their parents. At this site the adults continued to feed the chicks.

Piles of feathers along the river banks and in vegetated areas near the nest and creche areas show the effects of predation. It seems that approximately 25 chicks were taken by harriers, this is quite natural. However, 9 appear to have been killed by ground predators – perhaps feral cats or ferrets. This is despite ARRG having permanent traps either side of the river and putting several temporary traps near the colony. About 9 were also killed by a reckless four-wheel drive operator.

12/2/19 at second creche site, chick demanding to be fed

The last fledgling flew away on 19 February, just as the river had almost completely dried out in this area. Soon afterwards perhaps several hundred fledglings and adults were spotted feeding in an irrigated paddock just south of the river.

It seems that in excess of 400 chicks were raised – probably a good outcome given that this was the third nesting attempt made by the colony. With 768 nests and 400 chicks fledging, a productivity of 0.52 was achieved. Unnecessary deaths of chicks were minimized by ARRG trapping and by blocking of access to the river by ECan and ARRG. ECan rangers were also very proactive in trying to prevent interference with the colony. In future nesting seasons we will be continuing to try to keep traffic out of the riverbed and we are working on extending our trapping network. Rare native birds should never be killed by reckless people driving through signposted nesting areas. These signs should not be deliberately vandalised as has commonly happened.

The remains of a gull chick – killed by a harrier
Vandalised ECan sign near the colony, 2/2/19
Nests, 9/2/19
ARRG members counting nests between 2m spaced ropes, 9/2/19

January 14 2019

January 2019 update

ashleyriver annual survey, Predators, Trapping, Trapping, weeds annual survey, bird count, breeding, flood, predators, shingle, weeds, wrybill

The last update was written in mid-November, and as that was mid-season, a fair bit has happened since then.

Annual survey. This, the key event of our bird year, went ahead on Nov 24, co-ordinated by Bev Alexander and Grant Davey.

As Grant says in his excellent report, “Eighteen volunteers took part, this was enough to do a quality survey. The weather was cloudy with some drizzle in the upper reaches. River flow was approximately 9 cumecs as measured at the gorge. A small flood reaching about 82 cumecs had occurred on 9 November and bird numbers may still have been recovering after this. A more significant flood soon after the survey (November 26), measuring up to 140 cumecs at the gorge, would have severely impacted bird numbers.”

Indeed, we were very lucky to get this survey completed when we did. If you want a copy of Grant’s report, I can send you one. In brief, total bird numbers were about the same as last year, so we have seen a couple of stable years, after the big declines in 2015 and 2016. This was due to weed invasion, and after last year’s major flood clearances we were hoping for higher numbers, but not so – probably because this has been a disrupted season. However, wrybill numbers were considerably up – from 9 last year to 20, with the long-term average being 13.

Interestingly, and demonstrating how dynamic are braided rivers and their inhabitants, if the annual count had been 2 days later (after the flood), wrybill numbers could well have been zero, as I have not seen a single wrybill on the river since that event.

Bird breeding. With a couple of exceptions, this season will probably go down as one of the poorest, due to the floods which occurred at sensitive times. Fortunately, 4 of our 8 wrybill pairs managed to fledge single chicks before floods intervened, but for other species virtually all eggs and non-flying chicks were lost to the Nov 26 flood. Also swept away by that event was a large black-billed (BBG) colony and some smaller colonies of black-fronted terns (BFTs). I thought that was the end of the season for them, but not so – the BBGs soon resettled not far up-river, with the BFTs a km or so further down. Needless to say, we have kept a close eye on them, with Grant drone-counting the gulls regularly. There are just over 1000 pairs, now at the stage of hatching chicks. The site is a good one, being a relatively weed-free island with good water currents on both sides. As the river flow declines, the terns are not so island protected, and the wet season means that they are in amongst rapidly growing lupins. Terns cannot be counted from the air (drone), but there appears to be around 60 present – so probably 20+ pairs, also now at the egg hatching stage. The gull and tern colonies are all that is left of breeding birds on the river, so we cross fingers for a successful outcome.

Predators. Despite having over 180 traps out on the riverbed, the predator catch over summer is often low, and such is the case right now. Catches increase in the autumn / early winter as young animals are kicked out of parent territories and food becomes more scarce. The Group is currently reviewing its trapping, with the aim of having all the riverbed margin covered from around the estuary right up to the Okuku junction – a distance of over 20km. This will require over 150 new traps – so Geoff will be approaching our trap-making team in the near future. Even though we will always rely largely on volunteers, we have to face the reality that servicing a large number of traps (well over 300) will require a new approach – involving some professional input.

Weeds. The 2017 major floods did a superb job clearing weeds, and vastly increased the areas of clean shingle which are absolutely vital for successful bird feeding and breeding. However, the floods brought down a new load of seeds, and these cleared stretches are rapidly being recolonised. Without doubt, our major challenge in the near future is how to keep the core bird breeding sites clear of weeds. Aerial spraying would be the most cost-effective means, but use of chemicals in waterways will always be controversial, and we do not want to go that way. This autumn we may well ask for volunteers to clear key sites. Although only small areas can be treated this way, it is almost the only volunteer-team exercise we can easily organise out on the riverbed – and if there is a good turnout, the results are always more impressive than initially imagined. Machinery options are being explored for larger areas.

Humans. As stated in the last Update, it is pleasing to report that disturbance by people and their machines has been relatively minor so far this season. Compared to 5+ years ago, it is relatively uncommon to see fresh vehicle tracks on the riverbed. All the same, there has been violations, one of which could result in a prosecution. I am sure that our signs and the access blockages are the major reason behind this good state of affairs. We are committed to removing the blocks in February, once the season is over.

Shingle extraction. We have always had great support from the major shingle extractor in the Ashley-Rakahuri riverbed – Taggarts Earthmoving Ltd. This year they have been working in the Hillcrest area, and we have spent much time monitoring bird activity within their concession site. Some of the nests found and followed have been within metres of regularly used tracks, so we have been able to collect useful data relative to how well-informed gravel extractors can work in close association with breeding birds.

Documentary video. Over the last year, we have spent some time compiling video material for documenting how the Group operates over a typical season. Tony Benny from Oxford (used to work on ‘Country Calendar’) was the film-maker, and has recently sent us a draft of the 20-minute product. This is in the final process of editing, and has impressed all viewers to date.

Meeting. We had a general meeting on Dec 10, with 13 folk in attendance.

Award. In the last Update, it was related how the Group had won the 2019 Practical Management Award offered by the Australasian Wildlife Management Association. In early December, I went over to Tasmania to accept this Award at the Society’s annual conference in Hobart. On the framed certificate we received, it is stated ‘In recognition of outstanding best practice in wildlife management’. The presenter commented that we won from a strong field of entrants. The following morning I spoke of ARRG activities to the 180 conference attendees. We are fortunate that the AWMS goes out of its way to support applied conservation research and management. Consequently, they liked what we had to say, and a couple of subsequent speakers referenced us as the sort of community group they wanted to support. A number of attendees came up to me afterwards with positive comments and interesting questions. The conference covered a wide range of conservation topics, but as many of the over 100 presentations illustrated, the conservation challenges in Australia are quite different to ours – mainly as there are many mammals involved, plus a different set of predators. They do not have any mustelids or hedgehogs (and foxes only on the mainland – none in Tasmania). The most talked about predator of interest to us was the feral cat, which is arguably their major problem.

Coming up. With the season coming to an end, the focus moves to writing up results and preparing presentations for a shorebird workshop up in the Firth of Thames area (organised by the Pukorokoro-Miranda Naturalists’ Trust) in March, and another braided river workshop (organised by BRaid Inc) out at Lincoln in June. We are also setting up to review our trapping and weed control systems. Relative to the latter, look out for notification about weed control workdays this coming autumn. This will be one of the few opportunities for many members to get out there and do their bit.

January 7 2019

ARRG wins a trans-Tasman award for practical wildlife management

ashleyriver Awards, cats, management, Predators, trail cameras, weeds award, cats, management, predators, trail camera, trapping, traps, weeds

Conservationists throughout Australasia have recognised the work of the Ashley Rakahuri Rivercare Group (ARRG), to protect the unique braided river environment of the Ashley-Rakahuri River.

ARRG have won with the Australasian Wildlife Management Society (AWMS) annual award for practical wildlife management.

Out of eight finalists from throughout Australasia, the North Canterbury Group won the award for its practical work to protect and enhance the populations of endemic braided river birds in the Ashley-Rakahuri River, including such threatened species as the wrybill, black-fronted tern, black-billed gull and the banded dotterel. All of these birds nest on clean shingle banks and islands within the river environment.

“What I like about this award,” says ARRG Chair Nick Ledgard, “is that the judges would have known nothing about us before we entered, so we were competing in a ‘clean slate’ arena”.

For 14 years, ARRG has run a predator trapping programme along an 18km stretch of the Ashley-Rakahuri River from just West of Rangiora to where the river crosses state highway just north of Waikuku Township. Additionally, the group has annually surveyed the population of braided river birds in the protected area, compiling an important record of bird population and nesting success data. It has also conducted extensive public awareness campaigns to advocate for the protection of the riverbed and its inhabitants. One of the results of its advocacy is a local agreement to keep off-road vehicles out of the river during the bird breeding season.

“On the award certificate,” Nick says, “it reads, ‘in recognition of outstanding best practice in wildlife management’. We were told we had won from a strong field of entrants. The AWMS goes out of its way to support applied conservation research and management. I was told we were exactly the sort of community group they wanted to support.”

There were more than 100 presentations at the annual conference and it was clear conservation challenges in Australia are quite different to ours because of the presence of native land mammals in Australia, an issue New Zealand does not have (apart from two species of bat).

“The most talked about predator of interest to us was the feral cat, which is arguably their major problem and, of course, in a river that runs through urban areas such as Rangiora, a major problem for us too.”

Nick adds that one of the main ideas he took from the conference was the use of trail cameras to not only measure the activity of the protected animals, but also of their predators. “The trail cameras show behaviour we don’t normally get to see. This is particularly the case for feral cats which are most active at night. Knowing how, where and under what conditions feral cats predate our birds would be a great help in designing methods to maximise our control of these predators.

“I was also shown some thermo-imaging cameras. Open riverbeds would be ideal for these, and at night we could get to know every visitor (right down to mice). But the cost is still huge for the best gear and obtaining funding for such equipment would be too much for us.”

When asked what he considered to be ARRG’s biggest challenge for the future, he replied, “I felt it was keeping on top of invasive weeds, which can quickly reduce suitable bird feeding and breeding habitat. Our surveys show that we can keep on top of the predators in the controlled area with trapping, but weed control is an ongoing and repeated issue if we are to maintain the clean shingle areas the birds need to breed.”