31 August 2010

The big pitcher

Ecologists spend a lot of time thinking about how species in communities are linked together. While we have made progress in understanding this at small scales (like your backyard) we have seldom tried to understand this at large scales (like across continents). One of the reasons for this is that there are huge numbers of species in communities and the problem of dealing with them all is too difficult. However, some communities are not so complex. Hannah Buckley (Lincoln University) and her colleagues, Thomas Miller (Florida State), Aaron Ellison (Harvard) & Nicholas Gotelli (Vermont), realised that there are some communities that are easier to study. In a paper published in Global Ecology and Biogeography, the team looked at communities that live with pitcher plants over much of North America. Pitcher plants collect rainwater in their leaves and these pools are colonised by species of bacteria, insects and so on. The pitcher plants create a simple community that can be investigated at a several scales: different pitchers (or cups) within a plant, different plants within a local population, and across the plant’s entire distribution (continental scale).
The pitcher plant Sarracenia purpurea was the subject for their study and is a long-lived (> 50 years) carnivorous plant that grows in bogs, sand plains and pine savannahs across much of North America. The pitcher-shaped leaves are open to the sky and collect rain and snow as well as various species of animals and bacteria that happen to arrive in the cups. Many of the species, finding themselves trapped in the pitcher, drown and form the basis of a food chain on which other species feed who, in turn, provide food for predators. The plants are thought to absorb some nutrients, particularly nitrogen and phosphorus, from the decaying bodies.


Buckley collected the contents of pitchers from 39 sites across North America. When examined, across all sites, the researchers found 13 arthropod & rotifer species, 48 protozoan species and 29 bacterial morphotypes. Pitcher plants typically hosted 6 arthropod species, 9 protozoans and 17 bacterial species. Nearly half of the species found were only from one site, whereas 4 species that specialise in living in pitchers (three fly and one mite species), were found at almost all sites. Overall, and very surprisingly, pitchers at the same site were less similar to each other in species make-up than comparing pitchers at different sites across North America! That is food webs, and therefore communities, were more variable at the smallest scale that at the larger scale. This is probably not as surprising as you would first think. For example, the streets in your home town can be highly variable as to the businesses that you might find there but if you compare between towns they will generally all have a pharmacy, a supermarket, a fish’n’chip shop, hairdressers, a joinery and so on. It’s all about the scale you ask your questions at. And that is the key finding of this study.
This study emphasises the benefits of examining how communities change at a variety of scales and should serve as a model for others. Buckley and her co-authors intend to use this idea of simple natural communities in future studies to examine the effects of local and continental scales on how biotic and abiotic challenges affect species richness and community membership.

26 August 2010

Not-so incy wincy spider

Cor Vink, adjunct curator of spiders at the Entomology Research Museum, Lincoln University and research scientist at AgResearch, has recently published a taxonomic revision of the New Zealand Pisauridae (nurseryweb spiders) with his colleague Nadine Dupérré (American Museum of Natural History) – Vink CJ, Dupérré N (2010) Pisauridae (Arachnida: Araneae). Fauna of New Zealand 64: 1-60. A taxonomic revision takes a good look at what we know about species in a particular group as well as any new species that have been discovered since the last major look. The Fauna of New Zealand series will eventually aim to cover all of the species found there. Cor is New Zealand's leading arachnologist and has discovered many new species of spider. Nadine is a talented drawer of spiders and you can see some of her work in the latest Angelina Jolie movie Salt (one of the characters is an arachnologist).


Nurseryweb spiders are easily recognised in New Zealand by the nurseryweb that the female builds around the eggsac, which serves to protect the newly emerged spiderlings. New Zealand nurseryweb spiders do not build a web for prey capture and are sit-and-wait predators. Four closely related species of nurseryweb spiders are found in New Zealand; three on the mainland and one on the Chatham Islands. All species are endemic to New Zealand and are likely to be related to Australian species. The most common species is Dolomedes minor, which is found throughout New Zealand in scrubland, grassland, swamps, and marshes. Dolomedes aquaticus is found in open riverbeds and stony lakeshores throughout the South Island and in the southern half of the North Island. Another species, Dolomedes dondalei is found in shaded riverbeds throughout mainland New Zealand. The Chatham Islands species, Dolomedes schauinslandi, is known from only three islands (South East, Mangere, and Houruakopara Islands) and is nationally endangered due to its restricted range. Molecular evidence of interbreeding between two common mainland species, D. minor and D. aquaticus, was also discovered and this is being investigated further by B.Sc. honours student Vanessa Lattimore.

23 August 2010

Success for Nina Valley Restoration Group

Hurunui College established the "Nina Valley Restoration Group" at the start of 2009. Nina Valley is located near Lewis Pass and is a region of beech forest. The valley has a good level of accessibility with tracks running from the road to the head. A major goal of the group is to establish a breeding kiwi population. The group has successfully gained funding from BNZ Save the Kiwi and the Air New Zealand Environmental Trust.

The funding has been used to purchase 150 DOC200 and 40 Henry (resetting) traps to control mustelids, particularly stoats. Stoats have a large impact on bird breeding paopulations. In November 2009 about 20 volunteers - students, parents, and a couple of NZ Deerstalkers Association members - spread these out over 15 km of river valley in the Nina valley. The traps were checked and reset fortnightly by groups of 5-6 students and parents over the summer season.

The 2010 Youth Leadership for Sustainability Awards are a joint initiative between Environment Canterbury and Ngai Tahu recognising awareness of environmental and social issues among Canterbury’s youth. The individual award was open to students in Years 12-13 and recognised their work in sustainability, either through their own initiative or by supporting or leading a wider project. The group award celebrates the contributions of a youth organisation, marae or school. Nina Valley Restoration were placed as group category prize-winners, along with Lincoln Enviro Organisation and Youth River Action, in recognition of their excellent work.


The "Restoration Group" consists of around 20 students, ranging from 12-15 years old. It was set up at the beginning of 2009 by Hurunui College science teacher, Tim Kelly, and DOC ranger, Malcolm Wylie. Since then, the group has done kiwi-listening, and trapping and tracking-tunnel training. They have had hands-on opportunities to view kiwi eggs and chicks raised through the BNZ Operation Nest Egg at Willowbank.

Since the Group was formed staff and students from the Department of Ecology at Lincoln University has helped with installing and monitoring tracking tunnel (purpose built wooden tunnels containing inkpads and paper that record when stoats move through them). Also, the department has hosted a group of Hurunui student while they investigated stomach contents of stoats caught in traps at Nina Valley.

Tim Kelly has recently applied to the Royal Society of New Zealand for a 6-month teaching fellowship. If successful he will be hosted at Lincoln University while working with Drs James Ross and Adrian Paterson and his study will investigate new self-setting traps for stoats and possums.

How to have a lousy time in Durham

Durham, England, famous for its grand old city and cathedral, where bus loads of senior citizens spend their day dragging their Zimmer frames over the cobbled streets to admire ye olde England. More recently and probably more famous in New Zealand, Durham's castle and cathedral might be better known as Hogwarts School of Witchcraft and Wizardry, as seen in the Harry Potter films. So, what have Lincoln University and Harry Potter got in common? Not a lot, but it sets the scene for where my current fieldwork is based.

I am in northern England to sample birds for feather lice. As you sit and scratch, feeling small legs walking through your hair, you might ask why I would travel half way around the world to do this. The source of almost all of New Zealand's introduced song birds is the UK. Sparrows, blackbirds, skylarks and finches, amongst others, were brought to New Zealand by settlers to help create a sense of home. Along with the birds came their feather parasites, although not all of the species. It is the pattern of what made it and what didn't that is of interest to us and will allow us to better think about invasive species (see this previous blog). We know how the lice are distributed around New Zealand but have only minimal knowledge about their ancestral home, especially the northern areas of England where many settler-ships left from. To model UK distributions of chewing-lice, I have been catching selected bird species and processing them for chewing lice.

While you suffer winter in NZ, I am enjoying the UK summer. I arrived in the UK in early July and quickly made arrangements to join British Trust for Ornithology (BTO) bird ringers in the field. Bird ringing (or banding) is heavily regulated in the UK and takes at least two years to gain a licence to ring birds without supervision. Naturally, this is well beyond the scope of a Masters project. This means that I am at the mercy of suitably qualified people to complete my research. All of the ringers that I work with volunteer their time and they also pay for the rings and all other costs associated with ringing birds.


Apart from their natural love of birds, there are other reasons why these people ring birds: the BTO run various ringing programmes, such as The Constant Effort Sites Scheme (CES) and Retrapping Adults for Survival (RAS) that rely on data collected by these volunteers. The CES sampling protocol dictates that each site is visited once every 10 days during the breeding season (this means 11 visits). The effort at each site remains constant, i.e., the same number of nets in the same positions for the same amount of time. For example, at the Foxglove Covert CES they erect 30, 18 metre mist-nets, begin ringing at sunrise (4am in mid-summer) and remain ringing for 10 hours; whereas, at the Rainton Meadows CES they erect 8 mist-nets (a mixture of 12 and 18 metre nets) and catch birds between 7am and 1pm.

The benefit of CES for my fieldwork is that I can plan on mist-netting at least once every 10 days, weather permitting. Birds loose body heat rapidly when they get wet, so to avoid bird mortality, nets must be collapsed when it rains. Wind also affects sample effort; birds are less active in high wind and the nets become highly visible flapping about. More importantly, birds can also be injured in a moving net (e.g., broken wings and strangulation). CES sites are usually visited in the weekend, so I must decide on which to visit. Lately, I have gone where I catch the greatest number of birds, but soon, to increase the number of records for more rare species, I will have to concentrate on locations where specific bird species are caught.

This is a convenient segueway to the RAS (Retrapping Adults for Survival) scheme. Sites are selected where many individuals of targeted species will be caught for monitoring species survival rates. So far, as part of my study I have processed birds at yellowhammer, house sparrow and blackbird RAS sites. There are some species that I have few records for, so I need to find redpoll, songthrush and starling RAS sites to sample at. Which should fill the last five weeks that I am here.

While I am not delousing birds in the field, I process my samples in the lab (thanks to Biological sciences at Durham University). This entails sifting through my field samples under a dissection microscope. I have become quite tuned into finding lice floating about in a mixture of ethanol and flea powder, but it still takes about one day to process 10 samples. I have processed 135 birds (about 10% of all the birds caught at these sites) and blackbirds are by far the most lousy bird, both for prevalence and intensity.
Ok, gloves on and back to work....

11 August 2010

Banks Peninsula Biodiversity Workshop: Proceedings

The Biodiversity Workshop that was held at Akaroa in October 2009 is now available as a proceedings. The proceedings compile information from the various presentations given on the day and were put together by Mike Bowie, Rachel Barker and Tina Troup.

Over the course of a very successful day, scientists, conservation organisations and landowners came together to talk about conserving Banks Peninsula’s special plants, birds, lizards, fish and invertebrates. The proceedings run to 49 pages and are packed with information on on trapping various predators threatening the native species, how to conserve and/or restore habitats of native species present on Banks Peninsula as well as updates on the management of various endangered species, such as tui or little penguins.

You can read the proceedings here.