Friable curlew eggs could pose another threat to species, UK scientists say | Birds


A scientist has launched a nationwide survey of curlews, after noticing in a small-scale study that some of the eggs laid by the endangered birds were unusually fragile and crumbly.

If the problem is found to be widespread, the fragile eggs could pose a serious risk to the future of the species which has faced major declines in Scotland, England and Wales, and a overall decline of 42% in the UK between 1995 and 2008.

Dr Nicola Hemmings, a researcher at the University of Sheffield’s School of Biosciences, started working with the Curlew Recovery Partnership (CRP) conservation group last year.

She said: “I looked at a very small number of eggs because the CRP thought there might be fertility issues. All were fertilized and showed signs of embryonic development, but at least half of them had fragile flaky, brittle or crumbly shells. We have this indication that there might be a problem here. It should be noted that those eggs with particularly thin shells had embryos that died at particularly late development.

This finding worried her, so she decided to ask the partnership to get samples from across the country, to see if it is widespread and if there is a trend in egg quality and egg success. hatching.

Nest monitors have been asked to send failed eggs and egg fragments to Dr Hemmings, who will analyze them to see why they become so crumbly. “We want to assess how much of a threat this poses to curlew recovery,” she said, adding, “The first step is to determine if this problem is widespread, and then the next step will be to try to identify what the problem is, then what is causing the problem with these eggshells.

“We will analyze eggshell samples to look for environmental contaminants that could lead to poor eggshell quality and also look for evidence of poor nutrition.”

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If they’re able to identify a problem, conservation teams could work with area landowners to reduce pollution near curlew sites or help birds that aren’t finding enough food.

If the problem is inbreeding due to restricted population, rather than something that is easier to solve, such as environmental pollution, the outlook would be poor. However, it is hoped that another issue could be causing the problem.

Hemmings said: “The one thing that seemed quite optimistic based on our analysis last year was that the fertility issue didn’t appear to be a major issue. These eggs have been fertilized, which is the first thing people think of when it comes to genetic or inbreeding issues. Doing this kind of UK-wide assessment will help us identify if there are issues with particular pockets across the issue and if there are any fertility issues that arise.

It’s important that members of the public do not disturb the nesting sites, but conservationists involved in the study have been asked to keep an eye on the stranded eggs. It is therefore important to put the eggs in the refrigerator before sending them for analysis. They were also asked for larger fragments of hatched eggs, to allow analysis of shell thickness at various locations.

Curlew loss has been most dramatic in the lowlands, and birds below Birmingham are now estimated at a maximum of 300 pairs. It is thought that these birds could disappear in eight years if nothing changes. The curlew was added to the UK Red List in 2015.

Professor Russell Wynn, who heads the CRP, said: “The UK and Ireland are home to a quarter of the world’s breeding curlews, mostly concentrated in the highlands of northern England and Scotland. However, after dramatic declines in recent decades, they are now at real risk of extinction as a breeding bird in Ireland, Wales and much of the Lowlands of England.

“In these areas, we are seeing existing populations become increasingly isolated, and a lack of breeding success means there is a risk that they will now be dominated by aging and potentially infertile birds. This new research project will therefore inform conservation efforts in these areas by identifying the causes of egg failure and potentially alerting us to the impacts of chemical pollutants and/or poor nutrition on breeding and wintering grounds. curlew.

“There was a recent study that basically showed that the biggest type of blockage to population recovery in curlews is the early stages of reproduction – hatching and the successful survival of young chicks. Every egg is crucial and every clutch is crucial.


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