Sex may not be the first thing that comes to mind when you think of climate change. But for the collared flycatcher, the two seem to be linked in some mysterious way. As temperatures have risen, male flycatchers’ brilliant white forehead patches have changed from a valuable sexual signal into a liability.
Since 1980, ecologist Lars Gustafsson at Uppsala University in Sweden has been monitoring a population of collared flycatchers on the island of Gotland in the Baltic Sea. Every year, he and his colleagues have marked every bird in the population with numbered leg-bands, allowing the parentage, reproductive success and survival of many generations of birds to be tracked.
In recent years, Gustafsson’s team has noticed that the males’ forehead patches have been shrinking. Team member Simon Evans wondered whether this change was just a response by individual birds to changing conditions, or whether the population as a whole was evolving.
So Evans combed through 34 years of records. He found that early on, birds with larger forehead patches were more likely to contribute genes to future generations than their small-patched neighbours, but this edge reversed in the second half of the study period. Further analysis showed that this change was associated with higher springtime temperatures, a result of changing climate.
Oddly, birds with large forehead patches did worse in warm years, not because they had fewer offspring but because they were less likely to survive the following winter.
Evans, now at the University of Zurich, Switzerland, does not yet know why this is the case. But he speculates that males with large forehead patches must incur some cost for their display, perhaps through more aggressive competition against other males. Warmer springs somehow increase this cost. “These traits are evolving due to climate change,” says Evans.
Climate change is making birds less sexy!!!! We must stop this scourge!
Young baby jacanas are known as “downies” and are capable of walking and swimming as soon as they’ve hatched. Their father will not feed them, instead guiding them to feed and demonstrating how to hunt and uncover prey. He will also keep a close eye on them; shortly after hatching, the father will clear the eggshells out of the nest, possibly to deter predators, and will coo at and brood his new family. If he cannot find one of his chicks, the father will call loudly to try and attract it, and if a predator is detected, he will scream to summon the chicks’ larger and more powerful mother. He will guard and nurture his little family for 40 to 70 days.
The male jacana chosen to parent the chicks, called the receiver, is a devoted father. He will construct a floating nest by uprooting aquatic plants and stamping or shoving them together to create a dense and tough platform. He may create several of these nests and several different sites before the female is satisfied with one. After she has laid the eggs, parenting falls almost entirely on him; the female may shade the eggs from strong sunlight, defend the nest from predators, or incubate the eggs if the male is having a hard time finding food, but otherwise she is uninvolved. Incubating the eggs is the male’s responsibility; he will even move the eggs to a different site if he feels the nest is unsafe.
After the chicks are born, they rarely leave their father’s side; he will guide them to food, keep them warm, and violently chase rivals away. The male African jacana (last three images) goes one step further; should danger present itself, the male can literally tuck his chicks under his wings and carry them away.
If you are raised by
other species, then how do you know who you are? Although heterospecific
foster parents rear brood parasitic brown-headed cowbird chicks,
juvenile cowbirds readily recognize and affiliate with other cowbirds.
That’s because they have a secret handshake or password. Specifically,
the “password” hypothesis helps explain this paradox of species
recognition: Social recognition processes in brood parasites are
initiated by exposure to a password: in the case of cowbirds, a specific
chatter call. A new study appearing in the Journal of Experimental Biology describes the neural basis for password-based species recognition in cowbirds.
Am I the only one who isn’t annoyed by the chirping of the birds early in the morning? I love listening to them when I wake up. Their song reminds me of how beautiful the small things in life are.
lovingdread 