The cheatin' hearts of male antbirds

The female (left) and male antbird. Courtesy of University of Oxford

Female songbirds sometimes raise their young alone, without help from the father - if they have evolved where food is abundant and a female can succeed at parenting alone. But in habitats where a second parent is needed to keep up with the brood's appetite, songbirds have generally evolved to be monogamous, and both parents stick around to raise the young. And not necessarily just for the season; some bird species mate for life.

In such cases, a mated pair may use songs to strengthen the pair bond between them, and to defend their breeding territory from rival pairs.

But it turns out, avian adultery is not uncommon. Both males and females in mated pairs may have a wandering eye.

Nathalie Seddon and Joe Tobias of the University of Oxford studied the role of song in the adultery of Peruvian warbling-antbirds. In their latest research, published in the journal Current Biology, they report that an antbird couple will sing a "simple, precisely coordinated duet" when confronted by an intruding rival pair. But if an unattached female enters the scene, the duet begins to break down as the antbird "wife" starts jamming or blocking out the notes of her mate. She interrupts her spouse with her own music, to his great frustration. Said Dr. Tobias, "Males then countered this strategy by changing their songs in an attempt to avoid interference, resulting in a more complex acoustic display."

Animal duets are often harmoniously coordinated, but there has been a long-running debate about whether they are purely cooperative, or whether they reflect conflicts of interest. The Peruvian warbling-antbird offers an ideal situation for studying this question because on one hand males and females sing together to defend shared territories, and on the other males sing ‘solos’ as part of attracting a mate.

Single females are a threat to paired females because they increase the likelihood that males will cheat on their existing partner, or abandon them in favor of a new one. As it turns out, 'divorce' is common in antbirds. And so, the presence of an unattached female leads to a kind of acoustic battle in which males and females have different priorities.

According to Seddon and Tobias, their findings demonstrate that animal duets can be cooperative or manipulative, depending on context. Their study also provides the first evidence that individuals in duets try to avoid being jammed, which can have the effect of increasing the complexity of duets. The research helps to explain the recurrent evolution of complex communication signals in many lineages of birds and social primates, and according the authors may provide a useful clue to the origins of human music.

By Sally Kneidel, PhD with quotes from the sources below

Sources:
Nathalie Siddon and Joe Tobias. Rainforest duets are a battle of the sexes. University of Oxford. March 12, 2009. http://www.ox.ac.uk/media/news_releases_for_journalists/090312_2.html

Song of the antbird reveals avian adultery. March 23, 2009. Morning Edition, NPR.
http://www.npr.org/templates/story/story.php?storyId=102229821&sc=emaf&sc=emaf

Keywords:: birds antbirds Peruvian antbirds songbirds bird behavior birdsong animal adultery Nathalie Siddon Joe Tobias University of Oxford

Animals making tools...what else are they capable of?

A pair of rooks. Photo by Christopher Bird, news.bbc.co.uk

Animals are at it again. Acting human. Or rather, exhibiting behaviors that we once thought were exclusively human. We once believed, I might say, that these behaviors defined humans as better, different, smarter than all other living things.

I'm talking about tool use. As it turns out, tool use has now been observed in dozens of nonhuman species, including otters, monkeys, chimps, and 39 species of birds!

The most recent study involves rooks, a crow-like European species common in folklore. They're in the same family as our American crows, ravens, jays, and magpies.

The rooks in this study, reported just today (May 28) in the Proceedings of the National Academy of Sciences, were given access to food that could only be obtained by pushing a small rock off of a ledge into a tube. They quickly mastered that task. Christopher Bird of the University of Cambridge and Nathan Emery of Queen Mary College, London, challenged the birds further by moving the small rock farther away. Before long, a female rook, Fry, figured out picking up the stone and carrying it to the ledge. Her mate, Cook, followed her actions, then a second pair did.

The birds mastered various other tasks involving tools such as sticks and wires. They even figured out how to bend a wire to fashion a hook necessary to retrieve items. Although wild New Caledonian crows have been observed fashioning hooks in the past, the authors assert that this is the "first unambiguous evidence of animal insight, because the rooks made a hook tool on their first trial we know that they had no previous experience of making hook tools from wire because the birds were all hand-raised." The New Caledonian crows were known to use tools in the wild.

I love research that shows how smart animals are, and how we're not the supreme beings we think we are. What else are animals capable of that we don't know about yet? They deserve more respect, more of the world's remaining resources, than they're getting from their human relatives.

My previous post about New Caladonian crows making tools.

All my previous posts about tool use (or making tools) in animals.

Sources:
Christopher D. Bird and Nathan J. Emery. Insightful problem solving and creative tool modification by captive nontool-using rooks. May 28, 2009. Proceedings of the National Academy of Sciences.

Randolph E. Schmidt, Associated Press. Rooks figure out how to use tools. May 28, 2009. Charlotte Observer

Key words:: birds tool use rooks animal behavior making tools bird behavior animal intelligence

Birds Plan their Future Menus, Scientists Say

Western Scrub Jay photo courtesy of Arizona Game & Fish Division

Researchers say that Western scrub jays are the first animals to unambiguously meet the criteria for "planning" behavior. Scientist Nicola Clayton of the University of Cambridge in England reported her observations in the Feb. 22 issue of the journal Nature. The birds in the study were seen to store food in places where they were previously stuck with nothing to eat. They also were observed to cache certain kinds of food in spots where that kind of food had not been available in the past.

In humans, planning is the result of imaginary time travel. Whether the birds were engaging in imaginary time travel can't be known for sure. But behavior that seems to result from imaginary time travel has never been reported for any animal in research journals before now.

To set up the study, Clayton and her colleagues housed the jays in suites with two annexes. On some mornings, the researchers confined a bird in one of the annexes for 2 hours with no breakfast. On other days, the researchers kept the bird in the other annex, where food was available. So the birds knew which annex had food and which didn't.

For the experiment, the researchers served whole pine nuts to the jays. The birds could eat as many as they liked and cache the rest in either annex. The 8 birds in the test cached most of their nuts in the no-breakfast annex.

In a second experiment, the researchers offered the birds peanuts in one annex and kibble in the other. The birds cached more of each food in the annex that lacked it.

The researchers say the results show that the birds planned what they would have available to eat for future meals.

Other scientists - Sara Shettleworth of the University of Toronto and Thomas Suddendorf of the University of Queensland - concur with Clayton that the results show strong evidence of planning, much more so than previous behavioral experiments.

This behavior is different from, say, a dog running to the door at the sound of a car in the driveway, which is simply a response to a conditioned stimulus. It is also different from a cat lying next to a chipmunk hole, which may seem to be planning but is actually a hunt already in progress.

This behavior is not the same as a squirrel hiding nuts, either, which can be explained as just instinctive behavior with no imaginary reflection on how satisfactory the nuts will be at a future time.

The caching by Western scrub jays does seem to show "imaginary time travel" to events that could be weeks away - events which require some menu-adjustment in order to satisfy the choosy diners.

Source: S. Milius. "Bird plans." Science News, Volume 171. February 24, 2007.

Keywords: bird behavior bird intelligence scrub jays bird research planning behavior food cache