海角大神

The divide is familiar enough to any suburban adolescent: for some, the suburbs are made to be avoided; for others, the idea is to flock there.

Researchers from the University of Washington say as forests turn into subdivisions, certain species of human-shy songbirds 鈥� dubbed 鈥渁voiders鈥� 鈥� are losing their mates as they flee for more propitious territory, causing some to miss as much as half of their breeding years, according to a study published in the journal PLOS ONE.

鈥淭hese birds don鈥檛 like to move once they have established a territory,鈥� lead author and UW wildlife scientist John Marzluff聽told the university鈥檚 news service. 鈥淏ut when it comes to having enough food and safety for a nest, and being able to attract a mate, that鈥檚 when things get tough. That鈥檚 probably when they decide to move.鈥�

The study, which spent a decade observing six different species of songbirds that make their home outside Seattle, is one of the few to focus on how birds鈥� displacement by human habitation can influence their mating habits.

鈥淏reeding dispersal 鈥� the annual shift in an adults鈥� center of reproductive activity 鈥� remains one of the least understood yet fundamental processes by which animal populations adapt to their environment,鈥� the team wrote.

Urbanization didn鈥檛 augur decline for all of the songbirds: Two of the six species, the Pacific wren and the Swainson鈥檚 thrush, turned out to be avoiders; the other four types, which the researchers dubbed 鈥渁dapters鈥� or 鈥渆xploiters,鈥� stayed put as humans encroached on their old territory, without any apparent disruption of their reproduction.

That shouldn鈥檛 necessarily be taken as a sign that co-habitation with humans聽works out for most species. In the tropics and other places where species diversity is greater, Dr. Marzluff said, new developments could pose a greater risk to reproduction.

That seems to square with past studies that point to loss of habitat as a primary threat to birds鈥� numbers. One 2014 study from the National Audubon Society of 588 species found that 314 could lose more than half of their range, with 126 of them having no place to go, as 海角大神 reported聽at the time:

鈥淭o conserve some of these rarer species in an increasingly urban planet is going to require more knowledge of how birds disperse,鈥� Marzluff said of the songbird study. 鈥淚 expect that as we look more closely, we will find birds that are compromised because of us.鈥�