28 January 2010

New poisons for rat control

New Zealand has many problems with introduced mammalian pest species like rats. Rats are present in such vast numbers that the most common means of control is in poisoning wild populations. There has been a great deal of work put in to finding more effective and humane ways to poison pest species. Anticoagulant poisons, particularly 2nd-generation anticoagulants such as brodifacoum, are very persistent and have been detected in a range of non-targets including game species (i.e. pigs, deer etc.) and native birds. In the face of increasing anticoagulant contamination of wildlife in NZ and overseas, the present study was conducted to provide further information on Feracol® paste; a potential tool for control of rodents as well as possums in native forest ecosystems.

Feracol is a paste bait containing 0.8% cholecalciferol (vitamin D3). Cholcalciferol toxicity to birds is low (i.e. the LD50 for mallard ducks is 2000 mg/kg) and the risk of secondary poisoning for non-target species is low. In 1999, cholecalciferol was registered in NZ as paste bait for possums. This registration application was based on research in the early 1990’s, which demonstrated the high susceptibility of possums to cholecalciferol cereal bait.

The effectiveness of Feracol as a rodenticide was assessed in both cage and field trials. This work has recently been published in the New Zealand Journal of Ecology by James Ross of Lincoln University and other researchers based at Connovation. In the cage trials a total of 35 wild-caught and laboratory rats, including both ship and Norway rats, were presented with between 30-60 g of Feracol over 48 hours. Thirty four rats (97%) died in an average of 4.0 days following ingestion of the paste.

Field trials were then initiated with the paste delivered in either Philproof® or Striker® bait stations. Monitoring of rat numbers (using tracking tunnels) before-and-after the application of toxic bait was undertaken at three sites (Lions Hut, Mangaone and Pakoakoa) in the Te Urewera National Park. At Lions Hut, rat-tracking indices decreased from 78% to 3%; at Mangaone the reduction was 51% to 0%; and at Pakoakoa from 36% to 0%.

These trials demonstrate that Feracol is effective at reducing both moderate and high concentrations of ship rats. This is a promising result and providers users with an effective "non-anticoagulant" tool that can be used to effectively target both possum and rodents.

21 January 2010

After several decades, tui are again breeding on Banks Peninsula

Young tui. Flickr photo by Mollivan Jon
Last April, we blogged about the release of 30 tui (Prosthemadera novaeseelandiae, an endemic New Zealand song bird) onto Banks Peninsula to attempt to re-establish a self-sustaining wild population. Lincoln University lecturer Laura Molles has been leading the population monitoring. Laura and Karen Middlemiss, a Lincoln University summer scholar and Conservation and Ecology B.Sc. student, together with many keen local residents, have been spending their summer in south-eastern Banks Peninsula keeping a close eye on the tui as the birds explore what everyone hopes will be their new home.

Good news is that the released birds have chosen to stick around, rather than fly off back towards their original home in Maud Island. After massive historical deforestation, the south-eastern corner of Banks Peninsula is proving once again to be suitable tui habitat, thanks to increasingly large and mature areas of regenerating native forest and ongoing predator control. The second piece of good news is that the released tui have been breeding (!) and at least one nest has already fledged chicks. This amazing success less than 12 months into the project was reported in The Press newspaper on 18 Jan. 2010.

Despite the excellent start, the young tui population is certainly not safely into the woods yet. Several nests have already been hit by stoats and rats, despite intensive trapping around known nests. Stoats, especially, seem to be having a good year this year on Banks Peninsula. Also, thirty birds is inadequate to create a population with healthy levels of genetic diversity (see Lincoln postgraduate student Phil Cochrane's ecoLincNZ blog post on inbreeding depression in small populations of New Zealand birds). Because of this, a second release of Maud Island birds onto Banks Peninsula is planned for later this year and the Banks Peninsula Conservation Trust is fund-raising to pay for this translocation.

The tui project has been fortunate to join forces with local artist Clare Reilly of the Primitive Bird Group. Her spectacular tui paintings are currently on display at Gallery O in the Christchurch Arts Centre and proceeds from some of Clare's sales are helping to raise funds for ongoing predator control and the translocation of more tui. Laura Molles gave a talk and slide show about the tui release at the launch of Clare's exhibition on Tuesday 19 January and will repeat her talk in the gallery on Sunday 24 January at 2 pm.

If you're travelling on Banks Peninsula and see tui, Laura Molles and her team are keen to get your observations (where, when, what bird(s) (all released birds have colour bands on their legs), and what they were doing). Even if you don't get a close enough look to see the colour bands, Laura would still like to know where tui are on Banks Peninsula. You can send your observations to Laura or you can enter them online on the New Zealand Biodiversity Recording Network website (www.nzbrn.org.nz, the subject of a recent ecoLincNZ blog post).

03 January 2010

I spy road-kill

Nature doesn't operate at the speed of Twitter. Well, maybe it does for microbes. It takes more patience to see changes in populations of big things like birds and trees. It typically requires stitching together lots of observations over many years or over large areas. That's a very important thing to do. Biologists expect a lot of New Zealand's species to be responding to the many physical and biological changes to environments caused by people doing what people do.

Surprisingly, New Zealand ecologists are largely in the dark about most of these changes because big datasets of observations of wild species in and around rural and urban landscapes don't exist. These are where environmental changes are most pronounced. Or, when these datasets do exist, they're typically scattered about unconnected, usually only in hardcopy and in a whole mix of formats (one shining exception to this is the NZ Ornithological Society's wonderful bird atlas).

The New Zealand Biodiversity Recording Network (www.NZBRN.org.nz) seeks to change this. It provides an online place where everyone from school children to professional biologists can enter in what they see. You can either enter observations straight onto the website or download spreadsheet templates that you can use to enter offline on your laptop or iPod Touch. With everyone's eyes open to the natural world around them, we can see how nature is changing.

NZBRN was covered by TVNZ's TV One News recently, featuring Landcare Research's Colin Meurk and Lincoln University's Jon Sullivan. Click the image below to check it out (and note that the NZBRN web address is www.nzbrn.org.nz and not www.nzbrn.com as they mention in the story).

This summer, NZBRN is challenging people to record road-kill hedgehogs and other flattened fauna that they see on roads. Counting road-kill while driving or biking about New Zealand over summer is a convenient way to collect lots of observations.

One man who has already been doing this in the North Island for several decades is biologist Bob Brockie. In a recent article in the New Zealand Journal of Zoology, Bob and colleagues describe how hedgehog numbers in the North Island have declined by 82% between 1995 and 2005. And nobody knows why. Equally mysteriously, the decline doesn't seem to have happened in the eastern South Island, although we need many more recent observations to compare with past data to be sure of this. That's where you can help.


You can read more about counting road-kill and other projects involving NZBRN in the latest NZBRN newsletter, available here. At its simplest, NZBRN is great for creating species lists for locations and mapping species distributions. There are also all sorts of potential uses for NZBRN, including describing the spread of new pest and weeds, watching native birds reinvade New Zealand cities after pest control and the maturation of native plantings (hopefully), determining which species are most sensitive to climate change, or describing how species respond to large-scale conversion of farmland from sheep to dairying. The list of uses is only limited by the depth and breath of observations in NZBRN.

Ecologists in places like Europe and America have access to many big long-term datasets from urban and rural landscapes, often collected by keen amateur naturalists. These data have revealed all manner of changes, including shifts in species' seasonal activities and distributions and alarming declines in common birds and butterflies. Plants, birds, and insects are all responding to climate and landscape changes in different ways, disrupting the interconnections that make the natural world what it is today.

These are important things to know about New Zealand nature. For example, there has been concern raised here that many of our butterflies may be in decline (for example, watch this TVNZ Breakfast news item), but there's little hard data to back up that perception or to inform ecologists about the causes of any such declines. The observations needed to describe such changes in nature are not complicated or difficult. All we need is "What?", "Where?", and "When?", repeated over and over at lots of times and places and for lots of species. Also, recording when you looked for something and didn't find it is just as important (and there's an article on that in the latest NZBRN newsletter). If lots of people do this, together we'll know a lot more about the nature around us.

The best way to really get into NZBRN is to pick a few favourite species and places and start recording whether they're there or not each time you visit. A favourite place could be a summer holiday spot or your back garden or your drive to work. Favourite species could be fantails or all butterflies or, yes, even squashed road-kill hedgehogs.

Recording species certainly takes the monotony out of a long summer drive. When you get into the swing of it, it can be good fun. You'll find yourself noticing all sorts of things around you that you would otherwise have passed by.