"The hypothesis is that cavities are better protected, so woodpeckers, chickadees and other cavity nesters are less likely to be raided, so they tend to invest more in egg laying," Jetz said.
"Ground nesters, on the other hand, shouldn't put all of their eggs in one basket," he added, since predators are then more likely to find themselves with a free and easy egg dinner.
It would seem logical that all birds would hide their eggs in protective cavities, but he explained that, "not all the world is covered with trees." Birds in the desert, for example, often have no choice but to lay their eggs more in the open. Cavity nesting also is an ability that only a select group of birds evolved.
The scientists additionally determined that migrating birds tend to lay more eggs. Birds within certain families also tend to share similar clutch sizes. Big, flightless birds, for example, may often have large clutches containing anywhere from 10 to 74 eggs.
Robert Ricklefs, a professor of biology at University of Missouri at St. Louis, told Discovery News that, "Dr. Jetz's study is notable for its comprehensiveness and the excellent analytical applications." Ricklefs added that he was "especially gratified to see that seasonality of temperature, migration, and nest type play the dominant roles, as these factors have been particularly prominent in the literature." Given the importance of climate to birds, the global egg count, and consequently avian populations worldwide, may be in jeopardy due to climate change. It has the potential of not only harming a "bird's way of life, but also its where of life," Jetz said, referring to how many species may be forced to shift their geographical ranges. In the future, the new clutch size prediction model could help conservationists and other avian experts to better understand bird egg laying patterns in what Jetz and his colleagues call "a world of change." Related Links:
|
advertisement
Put Discovery News on Your Site!
|
-
our sites
-
video
mobile
-
shop
-
stay connected
-
corporate
