Hatching failure rates increase as bird species decline

A recent study published in the journal Biological Reviews has found that over one in six bird eggs fail to hatch, and hatching failure increases as bird species decline. Moreover, the experts discovered that hatching failure is a much bigger problem in the case of captive threatened species, with nearly half of their eggs failing to hatch. These findings provide evidence that conservation managers could use in their decision making for creating the best possible outcomes for endangered bird species recovery.

By assessing 241 bird species across 231 previous studies to examine hatching failure, the researchers discovered that almost 17 percent of bird eggs fail to hatch, which is nearly double than the number reported four decades ago. These values are even more worrisome in the case of endangered species, with 43 percent of eggs from threatened species bred in captivity being unsuccessful in hatching.

“Around 13 percent of bird species globally are currently threatened with extinction, and things are getting worse instead of better. Species on the verge of extinction have much higher levels of hatching failure compared to non-threatened species, and breeding birds in captivity appears to be having a negative impact,” said study co-author Nicola Hemmings, an expert in Biosciences at the University of Sheffield.

“There are important considerations that we need to make – does the benefit of captivity and other interventions outweigh the reduced reproduction of these species? For many species, these practices are absolutely vital for species survival, so we need to carefully weigh up the pros and cons of different approaches to ensure that we are doing everything that we can to protect birds from extinction.”

The scientists outlined four different conservation practices associated with lower hatching rates, including keeping birds in captivity, hatching eggs in artificial incubators, feeding the birds supplementary foods, and providing them with artificial nest boxes or sites. However, despite their potentially negative impact of hatching, some of these measures may still prove important to birds’ survival and reproduction. For instance, the eggs of some ground-nesting birds are at such a high risk of predation that leaving them in the wild would most likely result in their destruction.

“With this work we hope to provide vital evidence needed to understand how effective different management practices are at improving hatching success and aid population recovery,” said study senior author Patricia Brekke, a researcher at the Zoological Society of London (ZSL). 

“Conservation managers are doing an amazing job of preventing species decline, but they have an incredibly difficult job of making decisions when species are at the brink of extinction, on what tools to implement, and when. This kind of work provides the evidence necessary to improve decision making and hopefully improve recovery,” she concluded.

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By Andrei Ionescu, Earth.com Staff Writer

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