Study says sneaky females outwit males

 Sneaky females outwit males when pilfering food from close relatives (Credit: Alamy)


Sneaky females outwit males when pilfering food from close relatives (Credit: Alamy)

If you can’t find your own food, why not simply steal meals that others have stored for later?

A sneaky tactic perhaps, but one crucial for survival for the common songbird, the great tit.

What’s more, female tits are better at pulling off such heists than males, new research has discovered.

Outsmarting the opposite sex in this way may enable female tits to compensate for the males’ domineering personalities.

Great tits belong in the Paridae family. Their relatives in the same family, such as marsh tits, habitually store food.

Great tits do not. Instead they watch where their relatives store it and then pilfer their food caches. Continue reading

Great tit has a bird’s eye view when looking for dinner

Birds that hoard food for a rainy day better be sure that there are no great tits around to spy on where they hide their reserve of seeds and nuts. So says Anders Brodin and Utku Urhan of the University of Lund in Sweden, who found that great tits can remember the position of such hideaways up to 24 hours after seeing it cached. Continue reading

Bird alarm: Great tits use ‘predator-specific’ calls

Great tits use different combinations of notes in their calls to communicate information about predators

Great tits use different combinations of notes in their calls to communicate information about predators

Great tits use different alarm calls for different predators, according to a scientist in Japan.

The researcher analysed the birds’ calls and found they made “jar” sounds for snakes and “chicka” sounds for crows and martens.

This, he says, is the first demonstration birds can communicate vocally about the type of predator threatening them.

The findings are published in the journal Animal Behaviour. Continue reading

Great Tits Can Handle Climate Change: Songbirds More Resilient Than Expected

Songbirds are more resilient than we thought. New research reveals that a bird called the great tit can handle climate change far better than expected. (Photo : Flickr/Kev Chapman)

Songbirds are more resilient than we thought. New research reveals that a bird called the great tit can handle climate change far better than expected. (Photo : Flickr/Kev Chapman)

As the climate changes, species are shifting across the surface of our planet. Migration patterns are changing, breeding seasons are beginning earlier and animals are moving northward. With all of this happening, you’d think that birds would be drastically affected in a negative way. Yet new research has shown that, surprisingly, songbird populations can handle far more disrupting climate change than expected.

Spring may have started late this year, but the general trend shows an earlier spring for the last four decades. Because of this earlier spring, the seasonal timing of trees and insects also advances. Yet while trees and insects advance, songbird species such as the Parus major, also known as the great tit, lag behind.

In order to see how these seasonal changes affect songbird populations, researchers examined the great tit populations using almost 40 years of data from the songbird. More specifically, they looked at the great tit population in the Dutch National Park.

Their findings, unfortunately, didn’t seem to bode well for the birds at first. “It’s a real paradox,” said Tom Reed and Marcel Visser of the Netherlands Institute of Ecology in a news release. “Due to the changing climate of the past decades, the egg laying dates of Parus major have become increasingly mismatched with the timing of the main food sources for its chicks: caterpillars.”

In fact, it turns out the seasonal timing of the food peak has advanced over twice as fast as that of the birds. This means that while the caterpillars are showing up earlier with the earlier spring, the birds haven’t quite caught up yet which, in turn, means less food for the chicks.

Despite this fact, though, population numbers don’t seem to be down that much. Upon further examination of the data, the researchers found out why. Although fewer offspring now fledge due to a food shortage, it turns out the ones that do fledge have a higher chance of survival until the next breeding season. This offsets the current feeding issue.

“We call this relaxed competition, as there are fewer fledglings to compete with,” said Reed in a news release. “It all seems so obvious once you’ve calculated this, but people were almost sure that mistiming would lead to a direct population decline.”

In fact, some of the songbirds are benefiting from the earlier springs. Some of the great tits that lay their eggs earlier in the spring are more successful than the ones that lay latter and which produce relatively few surviving offspring. This, in turn, leads to increasing selection for birds that reproduce early.

While numbers aren’t being affected yet, though, researchers estimate that they probably will be in the future. The mismatch between egg laying and caterpillar peak continues to grow, which means that the impact of the phenomenon will also increase. While birds may be able to compensate for now, the future may cause a drop in population numbers.

source:scienceworldreport.com

So far, the great tit has coped with climate change

Its food supply out of sync, a European bird has escaped population decline – for now

DEMANDING DINERS Lively European birds called great tits haven’t kept up with climate changes that would require earlier nesting. Researchers have uncovered a quirk of population dynamics that’s giving the mistimed population some temporary protection.

DEMANDING DINERS
Lively European birds called great tits haven’t kept up with climate changes that would require earlier nesting. Researchers have uncovered a quirk of population dynamics that’s giving the mistimed population some temporary protection.

Though climate change has knocked little birds called great tits out of sync with their chicks’ food supply, the birds are maintaining their population numbers, a new study finds. But the way the tits cope may give them only a temporary reprieve.

“It’s buying them time,” says ecologist Tom Reed of the Netherlands Institute of Ecology in Wageningen.

Warmer springs mean that the peak food demands for Parus major chicks come later than the annual burst of local caterpillars. With less food, fewer young survive to leave their nests, Reed reports. However, the smaller resulting cohort of fledglings faces less competition for winter nuts and other resources. So a greater percentage of the youngsters survive through the winter than previously did, and — so far — this survival uptick has kept the study population from shrinking, Reed and an international team report in the April 26 Science.

These “quite acrobatic little birds” are close relatives of North America’s chickadees, Reed says. Decades ago, researchers set out nest boxes in a Dutch national park, and great tits readily moved in, forming a manageable study population.

Intense monitoring allowed Marcel Visser, also at Wageningen and a coauthor of the study, to realize that the nest timing was going wrong. In 1998, he and a colleague reported that the park’s great tits wereone of the first documented examples of birds getting ecologically out of sync with food because of climate change.

Springtime in northern Europe had become unusually warm by the 1980s, and the trend has continued. The birds don’t migrate so they and the insects are exposed to the same weather. But caterpillars are more sensitive to a change in temperature, Reed says. The caterpillars and birds also take their temperature cues at different times in the spring. The differences mean the caterpillars tend to peak a lot earlier. The birds, unfortunately, haven’t kept pace.

With 37 years of data in the new study, researchers also detected that this mismatch is changing evolutionary pressures on the great tits. The breeding pairs that nest a bit earlier now produce more surviving offspring, so the population is getting a little nudge toward the new timing regimen. It remains to be seen whether the climate will change too fast for this slow adaptation to protect the population.

This kind of climate-induced mismatch between animals and their food supply has become a common worry among biologists. Pied flycatchers, small birds that spend winters in Africa, don’t return to Europe soon enough to catch the spring insect bonanza. In West Greenland,, migratory caribou miss the best grazing. And in Norway, puffins are declining as the spring bloom of plankton often misses the main hatching of herring and shrinks the -food supply later needed to feed puffin chicks.

Still unclear is whether any out-of-sync species besides the great tits would get some relief from the benefits of lessened competition among youngsters. “We should be very cautious about suggesting that this is a widespread response to [food-supply] mismatch,” says ecologist Sarah Burthe from the Centre for Ecology and Hydrology in Edinburgh. Many studies, she says, already show that animals raise fewer total offspring in years with significant mismatches.

source:sciencenews.org