Tūturuatu Telegraph: Little genes, big conservation

Department of Conservation —  18/05/2022

The shore plover is described as a bird in need of urgent PR. With just 250 individuals left in the wild on several predator-free islands, it is one of the world’s rarest shore birds, facing issues related to real estate, genetics and a pandemic. Through collaboration and cooperation with tangata whenua, tchakat henu, community groups, and other stakeholders, the DOC-led Shore Plover Recovery Programme aims to turn the tide on this bird’s fate. The bi-monthly, ‘Tūturuatu Telegraph’ takes a closer look at what it takes to bring this unique species back from the brink of extinction.

Guest blog: Molly Magid, freelance science communicator and former Master’s student and Research Assistant at the University of Canterbury

Captive shore plover at Isaac Conservation and Wildlife Trust.
📷: Leonie Hyder

Ilina Cubrinovska, Olivia Janes, and I, along with our supervisor Professor Tammy Steeves, like to refer to ourselves as #TeamTchūriwat’. We have a lot of fun learning about these feisty little birds, also known as tūturuatu in Māori. Our team partners with the Hokotehi Moriori Trust, Ngāti Mutunga o Wharekauri, and the Department of Conservation Shore Plover Recovery Group to conduct genetic research on shore plover and to help inform conservation management of the species.

A juvenile on South East (Rangatira) / Hokorereoro Island is banded and blood is drawn for future genetic analysis of the wild population.
📷: Adrian Riegen

It’s a typical day in our office in the School of Biological Sciences at the University of Canterbury. We spread each diagram out on the floor, so we have enough space to look at them all. Lines on each page twist and cross over one another. I say to Ilina: “I don’t understand what’s happening with Meghan.” She responds: “Have you looked at her children with Harry, does that part make sense?” 

No, we are not looking at the seating chart for Meghan and Harry’s wedding, or the Royal Family at all. We’re actually trying to disentangle the genealogy of captive shore plovers. Our team is using a pedigree, which is like a family tree, to understand how each shore plover is related to one another. 

The captive population (which does in fact have a pair of birds named Meghan and Harry) was started back in the 1990s with 13 individuals brought from South East (Rangatira) / Hokorereoro Island in Rēkohu / Wharekauri / Chatham Islands. At this time, the shore plover population was in serious trouble. The birds had gone extinct on the mainland of Aotearoa New Zealand due to introduced mammalian predators and only a few small colonies remained in the in the archipelago. The captive population was started both as insurance, to make sure that the species would survive in the short-term, and to help shore plover thrive in the long-term by releasing offspring of captive birds back to the wild.

The female bird called Meghan at the Isaac Conservation and Wildlife Trust.
📷: Leonie Heyder

However, the captive population has encountered its own problems over the years. Individuals within the population are highly related to one another, which means there isn’t a lot of genetic diversity to go around. Genetic diversity refers to the numbers of different genes within a population, and just like with ice cream flavours, more is better. Having more flavours of ice cream, er, genes means that a species has more options to deal with stressful events like disease or climate change. Conversely, having low genetic diversity can cause issues in a population. In captive shore plover, low genetic diversity may help explain the fertility issues of the bird aptly named “Dudley”, or the difficulty that the captive population has had responding to avipoxvirus infection. For more on this, check out Ilina’s three-minute thesis video below.

Ilina Cubrinovska’s three-minute thesis entitled “Why dating your cousin in an apocalypse is a bad idea.

More than two years after the COVID-19 pandemic began, we all know how disruptive a virus can be, and poxvirus is no exception. Poxvirus causes red, swollen lesions to appear on a bird’s skin. In severe cases, these lesions can get infected with bacteria, and this may lead to death. Captive chicks and juveniles are especially susceptible to contracting poxvirus, which can prevent the release of young shore plover into the wild.

Intriguingly, the wild population doesn’t seem to have as big a problem with poxvirus infections. While wild birds still get sick, the infection appears to be milder, and they seem to get over it faster. This difference may be partly explained by the environment. In captivity, infection can spread more easily than in the wild, because of shared aviaries and resources.

To prevent this disease transmission, captive breeding facilities use insect-proof aviaries for young birds and separate sick birds from healthy ones. Additionally, captive chicks and juveniles have been immunised with a poxvirus vaccine for the past five years, but to date the vaccination hasn’t prompted a strong immune response in the birds. 

There’s also a possibility that genetics are playing a role. Here’s where our research comes in: the difference in disease outcomes in the wild and captive populations suggests that there might be a genetic difference that helps wild individuals to fight off the poxvirus. A previous analysis by Ilina shows that the captive and wild populations are genetically different from one another. Now, we are investigating whether wild individuals have specific immune genes that better protect them from poxvirus and/or serious infection.

For this research, we use what is called a “reference genome” and a “population resequencing dataset.” If you think of a reference genome like the picture on top of a puzzle box, the resequencing dataset are all the little pieces, one large handful for each bird. That picture helps us to put the puzzle together and figure out the genetic diversity of individual birds within the captive and wild shore plover populations.

Illustration of the reference genome (puzzle) and the population resequencing data (puzzle pieces).

We are also trying to fish out genes that are part of the immune system. Specifically, we’re looking for toll-like receptor (TLR) genes. If you think of the body like a castle, the TLRs would be the lookouts at the castle turrets who recognise enemies and warn the castle in advance, so it can prepare for an attack. If the captive population has low TLR gene diversity, then there won’t be as many flavours of TLR genes. Like a lookout that falls asleep on the job, birds may not recognise invading viruses, or they might recognise them but may not be able to mount a strong enough defence.

But there’s some good news – if there are flavours of TLR genes in the wild population that lead to a stronger immune response to poxvirus, then bringing in birds from the wild might help the captive population better deal with poxvirus infection.

Illustration of a TLR binding to avipoxvirus and signalling the immune system to respond.

In December of 2020, with support from Hokotehi Moriori Trust and Ngāti Mutunga o Wharekauri, the Shore Plover Recovery Programme decided to do just that – shore plover eggs from Rangatira / Hokoreoreo were brought into the captive population at the Isaac Conservation and Wildlife Trust. Exciting research by Brett Gartrell at Wildbase Recovery suggests that these wild individuals may be responding better to vaccination (more on this in the next blog), and our research will uncover whether they have indeed brought new TLR gene diversity into the captive population. For more on this, check out Tammy’s recent Tauhere UC Connect talk below.

University of Canterbury Tauhere UC Connect: Little genes, big conservation. Speaker: Tammy Steeves

These little birds provide a big hope for the captive population, and future generations of shore plover, both in captivity and in the wild. Conservation of a threatened species is a long game, and every small step is a step in the right direction. Furthermore, this work can only be achieved together with our partners – teamwork, after all, makes the dream work.