To save a bird, collect eggs or leave them in the wild?
It’s the ultimate last-ditch effort to save a bird species: Gather some eggs and attempt to breed a population in captivity. But this isn’t always the best course of action, scientists argue. In the case of an endangered bird called the great Indian bustard, the species might have a better chance of survival if we focus on conserving its habitat and leave the animals alone.
The great Indian bustard is a tall, leggy, brown-and-white bird resembling an ostrich. In 1969, about 1,260 of these creatures roamed the grasslands of India; by 2010, thanks to hunting and the development of power lines and farmland, the number dwindled to 100-300. In response, government officials said they would start a captive breeding program to save the bustard.
To determine whether this was a sound strategy, researchers developed models predicting how a captive population might fare under various conditions. They accounted for factors such as the number of wild eggs collected per year, nesting success rates, and the quality of the breeding program — for instance, the staff’s expertise level and the ability to contain biohazards. The team also estimated the likelihood of events such as bird injuries and disease.
When considering a range of program quality values and assuming that people collected 5 to 10 eggs per year for five years, the researchers found that the captive population would have a 73 to 88 percent chance of dying off in 50 years. Even if the quality of the breeding program was above average, the risk of failure would still be about 23 to 50 percent. Lowering the risk would require “the highest level of performance simultaneously across all aspects of rearing, establishment and breeding protocols,” the authors write.
The team also considered a scenario in which people did not collect any eggs and gradually improved the birds’ habitat over the course of a decade instead. This conservation strategy would yield more wild adult female birds during the 50-year period than an above-average captive breeding program, the researchers report. “Those inclined to attempt captive breeding should therefore reflect deeply on the human, financial and physical resources they will need to command for half a century into the future,” the authors warn. — Roberta Kwok | 11 June 2015
Source: Dolman, P.M. et al. 2015. Ark or park: the need to predict relative effectiveness of ex situ and in situ conservation before attempting captive breeding. Journal of Applied Ecology doi: 10.1111/1365-2664.12449.
Image © Prajwalkm | Wikimedia Commons
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