Threatened Mauritius Kestrel survives by living life in the fast lane
Release Date 20 February 2014
Researchers at the University of Reading have discovered that a threatened species of kestrel has sped up its pace of life to ensure its survival in the face of man destroying their natural environment.
In 1974, Mauritius Kestrels were labelled ‘the rarest birds in the world' with only four remaining in the wild, due to the loss of their native tropical forest habitat and the widespread use of pesticides.
The birds that have been forced to live near farmland have adapted to have more offspring earlier in life and have shorter life expectancies - effectively living fast and dying young. There are now around 400 kestrels on Mauritius. Despite this success the researchers warn this is a wake-up call to the effect of human activities on wild animals.
Dr Sam Cartwright and colleagues from the School of Agriculture, Policy and Development compared the breeding habits of Mauritius Kestrels that were born in their more natural, forest habitat with those born in areas in close proximity to open farmland. They found that birds coming from these manmade, agricultural habitats grew up to produce the same number of offspring as those living in their normal, forested environment.
Dr Cartwright said: "The Mauritius Kestrel has hit ‘the fast forward button' on its reproductive cycle. The strategy is a good one: breeding when younger compensates for the increased risk of dying sooner and is testament to how resilient this species is."
With less than two percent of their normal tropical forest habitat now left on the island, many birds are now forced to nest surrounded by vast fields of sugar cane. In forested habitat the kestrels are able to feed their chicks their native prey, tree-living geckos, but in sugarcane areas the researchers suspect the birds are also eating different prey, such as shrews and larger ground lizards, that were introduced by humans to Mauritius.
The researchers believe that kestrels from the agricultural territories are being born with a ‘lead-spoon in their mouths', the potentially less nutritious food impacting on the birds once they reach adulthood.
Dr Cartwright added: "These changes seen in adult life are entirely brought about by what the birds experience when they are young. Research done in human and animal subjects suggests that the quality of the childhood environment is important for the future health of the adult. But, as far as we know, this is the first time that anyone has shown in wild animals that habitat change caused by man can have this type of lasting legacy effect."
The research team analysed 23 years of data on the Mauritius kestrel population. They found that females born in territories affected by agriculture produced more offspring in their early years of adulthood than females from forested territories. They also reached their peak breeding output earlier, around the age of four, and then declined rapidly after that, whereas the forest females kept producing similar numbers of surviving offspring throughout life - and lived longer doing so. These differences were not related to the environment the birds were breeding in.
While these birds have survived, Dr Cartwright emphasized that their shifted life history should serve as a warning about the extent to which human activities have already influenced other wild species.
Dr Cartwright said: "Given the rate of human-induced habitat change the patterns we've reported could be widespread but are poorly documented. Most studies only look at the immediate impact of habitat change. Other species may respond differently, with more serious consequences for their survival in new, modified environments. We may yet see delayed consequences of the changes we've already made to habitats, such as large-scale forest clearance. This really serves as a warning that we need to be prepared for long term consequences to the changes we've already made."
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Notes to Editors
Photos credit: Dr Sam Cartwright
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