Displaying items by tag: Predator control

Tony Roxburgh, chair and trustee of the  National Wetland Trust provided the AGM with a glimpse of happenings with wetlands in Waikato.

The Trust plans a state-of-the-art interpretation centre, with research and educational facilities, wetland gardens and heritage trails on land next to Lake Serpentine in the Waipa district. This is one of 69 peat lakes in Waikato.

Issues to be worked through include highway access and formal agreement with the  Department of Conservation. DoC has already given approval to construct a 1.4 km predator fence around 10ha of the reserve at Lake  Serpentine near Ohaupo.

Tony said the plan includes a visitor concept plan, an interpretation plan, business plan and landscape developed for the site. These were funded by grants from Transpower, Trust Waikato and Waikato Regional Council (Environmental Initiatives Fund), and  supported by Waipa District Council.

They are looking at the best way to restore wildlife, including the feasibility of a predator exclusion fence. Funding from the Waikato Catchment Ecological Enhancement Trust, and a grant from the DoC’s Community Conservation Fund allowed them to produce a re-vegetation plan to restore vegetation and habitat.

Students of Te Awamutu School have been searching for native and exotic fauna, and have been the first to confirm long-tailed bats at the site. Other species confirmed include Australasian bittern, North Island fernbird, Black mudfish and Spotless crake.

The pest fence was completed in June this year and they now need sponsors and  donations to help with pest eradication and  re-introduction of native species.

Other work in the Waipa district includes Lake Ngaroto one of the peat lakes. It currently floods the peat and Tony said this could be one of the larger projects for the Waikato basin aimed at reducing loss of wetland and preserving the quality of the peat lakes.

Matuku, Forest & Bird’s sanctuary, is approximately 120ha of regenerating mixed kauri and podocarps that merges into West Auckland’s Te Henga wetland, the largest in the Auckland area.

Visiting a dozen years or so ago, Sean O’Connor and Ossie Latham  declared to John Staniland, the resident guardian, that it was ideal for pateke although the whole valley would need predator control. Finally in 2012 the current Pateke Recovery group leader Tiff Browne and Nigel Miller agreed the blend of forest, swamp, and farmlands  offered all that pateke desire. With the large dune-impounded Lake Wainamu just over the ridge it would also be part of the habitat any  released pateke would utilise so that (area) also needed predator control. And while you’re at it they’ll (pateke) probably use the small estuary at the beach so include that!

Since 2002 the Ark in the Park project had been steadily expanding predator control to the current 2400ha and its north western boundary is conveniently the eastern boundary of the suggested predator controlled area.

The Ark has successfully introduced robins, whitehead and kokako and has an extensive mustelid and rat control program. Additionally a volunteer beach care group have been controlling predators for some years and have seen the return of New Zealand dotterel for their efforts. Other volunteers run a trap line at the north of the beach where on a headland there are five species of shearwater; the highest number cohabiting on a mainland site.

I was able to get grants from WWF, and Auckland Council Biosecurity to purchase traps both DOC200s for mustelids [the stainless steel model owing to the proximity of the wild West coast salt air] and also Belisle kill traps for feral cats.

Although the existing trap lines at the beach and at Matuku are fairly short and well managed by volunteers the new requirements have two long trap lines each over 12km and therefore too long for a sustained fortnightly trap checking by volunteers. Another grant gained from the Auckland Zoo Conservation fund is for a contract trapper who will  alternate the long lines.

Fernbird sightings and perhaps territories are to be recorded, as they  believe fernbird will be an indicator species showing a positive response to predator control. Over 100 traps were placed during September and between volunteers doing the shorter lines and a contract trapper doing the long lines we hope to maintain the effort year round. So far the perimeter traps enclose over 1000ha.

Robins from the Ark in the Park sanctuary have dispersed and have been seen around the lake; a kokako has also visited Matuku and tomtit are now being seen at Matuku so the original vision of the Ark in the Park, “ From the ridges to the sea” could become a reality with this new venture aimed at bringing back pateke. The potential then is for other waterfowl and rails to become established in the wetland and gradually disperse  upriver toward the Ark.

Check it out at forestandbird.org.nz

If you live in the Auckland region and see or hear a Red-vented bulbul, ring 0800 08 99 66 and you could receive a $1000 if your information leads to a capture. Reward period runs to the end of February.

The reward for information leading to the  capture of this pest bird was increased from $300 to $1000 in October last year. The reward is for information that leads to the capture of this invasive pest. Capturing and eliminating this bird is important.

Red-vented bulbuls can cause significant  damage to fruit and vegetable crops and they chase and attack other birds. The Ministry for Primary Industries, Department of  Conservation (DOC) and Auckland Council are working together to track and eradicate the red-vented bulbul in Auckland.

The response team working to eradicate this pest bird, which comes from Asia, need  information of sightings.

“We’ve had more than 70 calls about possible sightings since we offered the $300 reward, but are still working to capture one of these birds,” said DOC spokesperson Liz Brooks. “We’re asking the public to keep looking for red-vented bulbuls and to call 0800 80 99 66 if they think they see one. To encourage this we increased the reward to $1000 for a call that leads to a capture,” said Ms Brooks.

“We think there are at least five red-vented bulbuls in Auckland which most likely arrived by ship or yacht. They’ve arrived in Auckland twice before and were successfully eradicated. We want to eliminate them before they make themselves at home,” said Ms Brooks.

The red-vented bulbul is one of the most  invasive bird species in the world and in New Zealand is listed as an unwanted organism  under the Biosecurity Act 1993. The maximum penalty for importing, trading, releasing,  exhibiting or breeding a red-vented bulbul is five years in prison or a fine of $100,000.

Red-vented bulbuls are confirmed to be located in three clusters in Auckland: south Auckland (Mangere /Manurewa/ Alfriston), west Auckland (Henderson / Te Atatu / Massey) and on the North Shore (Devonport / Belmont / Takapuna). There’s also been a  confirmed sighting on the Whangaparaoa Peninsula.

There have also been unconfirmed sightings in Orakei, in central Auckland, and at Walton, between Morrinsville and Matamata in Waikato.

Keep an eye and an ear out for red-vented bulbuls. They have a very distinctive call,  unlike other birds. They are easy to spot, a medium-sized bird, around 20 centimetres in length, about the size of a starling. They have a black head, a dark back, grey-white belly, and a distinctive crimson-red patch beneath their tail.  Call 0800 80 99 66.

Their distinctive call can be heard at: http:// www.biosecurity.govt.nz/pests/red-ventedbulbul.

Eleven volunteers from the New Plymouth branch of PricewaterhouseCoopers spent a day out of the office as they helped replace over 90 stoat traps along the Curtis Falls Track in the Egmont National Park.

The old traps came out of the boxes and new stainless steel ones went in. Replacing a line like this can take a couple of weeks so the volunteers really made a difference. With each person carrying six traps in and another six out as well as some tough climbs along the way, it was a big day.

This trap line protects the whio living along streams and rivers such as the Maketawa and they form a network that covers around 7000 hectares. Last year was a record year for whio ducklings in the Park with 33 ducklings hatching in the wild.

 

Another volunteer, Ian Street enjoys the Onaero Domain where he spends a lot of time at his Onaero beach batch and helps out by looking after a trapline and keeping an eye on weeds in the local reserve.

A whitefaced heron also enjoys the Onaero Domain and batch dwellers say he’s been around for about 14 years. “He had a mate,”said Ian, “but she died some time ago.

Recently though he’s found another.” 

 

The heron seems to know when Ian’s at home. He walks up to the front door and taps on the door. “He visits regularly,” said Ian. “I give him a little bit of fresh mince sometimes and away he goes.”

Whitefaced herons are New Zealand’s most common heron. They arrived from Australia in the 1940s so they’re considered native. This one’s been around long enough to be called a local.

Tāwharanui Open Sanctuary reintroduced pateke between 2008 and 2010, with 148 captive reared ducklings released in total. An earlier release in the 90s failed due to inadequate predator control, an unfortunately common occurrence for pre 2000 pateke releases.

 

More recent releases within the predator free open sanctuary have successfully established a population of approximately 30 pair, with pateke and ducklings regularly seen throughout the park. Tāwharanui pateke have also dispersed from the park and have established as two new satellite populations at nearby Christian Bay and Omaha, as well as supplementing remnant population on Kawau Island.

Matt Maitland
Senior Ranger Open Sanctuaries
Northern Regional Parks

 

The release of captive reared Pateke by Ducks Unlimited (NZ) in the Northland area between 1980-1992 had a number of positive outcomes, particularly at the 350-hectare government owned Mimiwhangata Farm Park during a brief period when predator control was being carried out. 

 

Pre-release aviaries were used and supplementary feeding took place.

 

3½ half months after the release of 64 captive reared Pateke at the Mimiwhangata, Farm Park in 1986 all 64 Pateke were believed to be still alive (Hayes 2002).

 

Starting in 2009 a150 captive reared Pateke have been released in Fiordland, but it is too early to predict the outcome of this programme. 
Pateke were once widespread throughout Fiordland, the habitat is still excellent and with ongoing predator control a South Island population could be re-established.

 

The 2000 audit of the pateke recovery programme

Recovery mode

Between 1975 and 2002 there were 2000 Pateke released into mainland wetland sites, with all releases failing to slow the species decline, largely due to:

 

In early August Steve Playle completed the trapping maintenance down at the wetlands for the month. It was the first servicing of equipment for the new financial year.

Result were 7 ferrets, 2 weasels, 6 rats, 3 hedgehogs, 3 harrier hawks and 2 magpies.

 

“We have cracked 50 ferrets since trapping commenced last July. A big tabby cat was swimming from the new Wairio bund out to the sprayed willows when I approached it on the quad. Pity I wasn’t carrying a firearm as it would have been easy to dispatch. Water levels were very high in places so some traps were
not able to be serviced.

 

“I saw a slate grey Bittern in the Mathews drain almost opposite where DoC launch their boats in Boggy Pond. I saw a second darker coloured Bittern at the southern end of the Stage one area of the Ducks Unlimited Restoration block. Great to see!”

 

Heavy rain prevented Steve from getting traps out at that time but he was out again the next week. Lake Rototawai was serviced also. He also took a cat, 1 rat, 1 hedgehog and a mouse from traps at Te Hopai Lagoon.

Steve regularly services traps in the areas we monitor. In July, almost 12 months since the first Timms traps went on the ground at Boggy Pond/Wairio Wetlands he caught 3 cats, 4 ferrets, 2 weasels, 4 rats, 12 hedgehogs, 4 mice, 6 magpies and 1 harrier hawk.

For the year total predators removed from this job are; 20 cats, 43 ferrets, 1 stoat, 13 weasels, 159 hedgehogs, 52 rats, 29 mice, 10 magpies, 2 harrier hawks and 1 rabbit.

 

During duck shooting season Steve reported we lost a total of 3 DOC 250 traps and 2 Timms traps to light fingered people.

 

Steve also did the first service of the Lake Rototawai predator control sites on July 4 and cleared 2 cats, 2 hedgehogs and 1 mouse from the traps. All bait stations were empty of bait too. The Te Hopai Lagoon traps were serviced and he took 2 very large cats, 3 hedgehogs and 1 mouse from those traps.

Wario September 5  - Steve completed trap servicing down at the wetlands for the month. Predators caught were 2 cats, 6 ferrets (plus one that Jim Law took from a trap making a total of 7), 1 weasel, 3 rats, 8 hedgehogs, 8 mice and 2 magpies.

 

Steve reports he saw a Bittern about 60 meters south of the viewing hide on the Boggy side of the stop bank and he saw another at Pounui Lagoon.

Steve will have commence fortnightly servicing of the traps at both of these
operations until breeding season is finished around the end of February.

“As a matter of interest we have already caught 14 ferrets at the Boggy/Wairio wetlands for August and September so it just shows we cannot take the handbrake off regular predator control any time soon,” said Steve.

Counting every rat, mouse or mustelid trapped may be satisfying, but it is irrelevant in the war against predators and may be lulling us into a false sense of security, guest speaker Professor Carolyn (Kim) King told DU members at the conference.

 

In her speech, Maximising the Duck Harvest, Prof King, from the School of Science at Waikato University, thanked Ducks Unlimited, which like many hunting clubs around the world, had turned itself into a conservation group, supportive of conservation research organisations and with members who were observant naturalists contributing to conservation efforts.

 

She said a good harvest operation:

 

As an example, she said, the winning team in the Great Otago Bunny Hunt in 2012 bagged 1035 rabbits as its contribution to the 10,424 tally from the 24-hour event. During the 21 years of the event, 253,735 rabbits have been killed (mean: 12,082 a year) but it has made no difference to rabbit numbers.

 

Harvesting is a dynamic target-habitatpeople system in which:

 

Using an example from Wiltshire in the UK she demonstrated how a predator control experiment produced a surprising result. In two areas of farmland, 1km apart and with similar habitat, predators were controlled in one area for three years and then in the other area for three years.

 

The study had been based on the assumption that habitat on UK game estates was the only important factor but the results clearly showed a big increased harvestable yield of grey partridges in whichever area was subject to predator control.

 A computer model developed from the study predicted that the highest populations would be found where nesting cover for the partridges was increased and predators were removed, even if shooting was permitted as well. Key is the interaction of habitat (controls productivity) and shooting mortality. If nests are protected, more young survive, so shooting can substitute for nest mortality caused by predators.

 

Using a NZ example to highlight the relationship between habitat and mortality, Prof King referred to wetlands in the Upper Waitaki area. In 1850, wetlands and swamps covered 71,000 hectares, but the effects of human activities has been devastating with 7300 ha swamps converted to pasture, more fragmented; 22,300 inundated by hydro electric schemes; 4200 ha braided riverbed dewatered (9% loss); 22,300 ha new open water habitat + 300 km more shoreline which doesn’t suit riverbed birds; predation is heavy and breeding rate low on the remaining 41, 700 ha wetlands (40% loss).

 

Food supply has the greatest effect on bird populations. The braided riverbeds were dewatered or turned into open water habitat, which did not suit the birds adapted to feeding on the riverbed, exposing them to predation and a drop-off in breeding.

 

Prof King said the deadliest predators for ducks were egg-loving hedgehogs, ferrets, stoats, rats, mice and cats. An Upper Waitaki Basin study of predation on the nests of dotterels, terns and stilts showed that cats, ferrets and hedgehogs did the most harm to nesting birds in that area.

 

She said, “We know we can kill predators, so what’s the problem?” Counting a pile of dead pests can be enormously satisfying but it does not tell us what we want to know, which is how many are still there, how to account for those that replace those dead ones, and how to know if we have taken out enough predators to benefit the birds we want to protect. That boils down to what actually determines the numbers of animals – both the predators and the birds.

 

Ferret numbers are controlled by rabbits (their main food source), not trappers. The rabbit yield is not declining: rabbits and ferrets are co-evolved prey.

 

A pilot trial in 2005 presented another serious problem – trap avoidance. Radio-collared ferrets in a study near Tokoroa were tracked by an aircraft which flew over the area during the day.

Nine of the 15 ferrets were located. Monitoring sites showed that six of the ferrets made 22 approaches to 2 experimental recording sites, which could have been traps, but only three entered the tunnels. On the final extensive trap-out, four of the 15 eluded capture, although their radio signals confirmed they were still there.

 

The following year collars were put on 30 ferrets west of Lake Taupo and a new toxic bait dispenser was used. Over five weeks, only 12 visited the bait stations and only eight took the bait. The monitoring regulations said every ferret had to be accounted for but of the 13 known survivors, only two could be caught.

 

In kiwi sanctuaries in Northland, stoats were refusing to go into the bait tunnels and it was only a brief 1080 operation that stopped the decline of kiwi chicks. Though it is awful stuff, we have to use the tools we have until we come up with something better, she said.

 

Predators are intelligent and quickly learn to avoid new devices presenting danger to them. In Britain, American mink, which escaped from fur farms in the 1950s, had become a serious threat to the native water vole (Ratty in Wind in the Willows). The mink, like rats, are good swimmers which means they can avoid land traps set on river banks. The problem was tackled by using traps placed on floating rafts, which might be appropriate to adapt as a control for Norway rats here, Prof King said.

 

 

New technologies are absolutely essential and can transform results. She said at a 1976 conference that she attended senior scientists said rat eradications on islands were impossible, but they were wrong. The invention of brodifacoum in the 1980s plus precise bait placement enabled Breaksea Island to be cleared of Norway rats in three weeks in 1988.

 

“That’s what we need – some kind of new technology that will break the mould, something different... One of the definitions of insanity is to keep on doing the same thing and expecting different outcomes,” Prof King said.

 

We can and must increase the intensity of predator control, but to be effective it must add to the natural mortality. Mustelids were introduced to control rabbits but rabbits were breeding at a faster rate and their numbers were unaffected. The mustelids were only substituting for natural mortality.

Only when rabbit breeding is reduced for other reasons (drought, 1080), can mustelids and/or trappers add to their normal losses, and achieve a real effect

Failures were usually due to some combination of:

 

 

 

Prof King said, on the other hand, some of the common features of successful predator control were a combination of:

 

 

Prof King concluded by saying Predator Free NZ was still a long way away but “don’t despair, history is encouraging!”, and DUNZ would play an important role.

In the meantime we must keep using whatever tools we have so we still have native species surviving by the time we develop something better, protecting duck nesting sites is possible and needed now.

 

PFNZ is going to be much more difficult as it requires development of as-yet-unknown, 100 per cent acceptable methods to control predator replacement rates.