Woodpecker wars are intense and even draw a crowd
Acorn woodpecker battles over prized territory are serious business.
- Acorn woodpeckers are highly socialized birds who are, let's say, unusual.
- Small teams of acorn woodpeckers battle for days over coveted territory.
- Up to 30 spectators attend the battles, leaving their own territories unattended to do so.
Ornithologists already knew that acorn woodpeckers, Melanerpes formicivorus, were gonzo. They're major hoarders of acorns, females eat each other's eggs, and then there's the group sex. It turns out they're also committed, tenacious, and ferocious warriors when it comes to competition for high-quality territory. Small teams of acorn woodpeckers battle over abandoned "granaries," tree sections with thousands of holes dug into their bark by birds — the holes are ideal for storing acorns.
"When you're approaching a big tree with a power struggle from far away, you'll first hear a lot of acorn woodpeckers calling very distinctly, and see birds flying around like crazy. When you get closer, you can see that there are a dozen or more coalitions of three or four birds fighting and posturing on branches. One group has to beat all the others to win a spot in the territory, which is really, really rare in animals—even in fantasy novels it usually boils down to one army against the other."
The research also reveals that large numbers of acorn woodpeckers who are not themselves involved in the action watch the battle royal unfold as spectators.
Credit: Ondrej Prosicky/Shutterstock
Much of what's known about these birds, including the new research, comes from a long-running project at the Hastings Natural History Reservation in California's Monterey Country. Acorn woodpeckers first arrived at the sanctuary in 1968 and have been under observation since 1974. The birds are common in the oak woodlands of western North America.
Acorn woodpeckers have a polygynandrous mating system, something that's rarely seen in nature. A group will consist of as many as seven co-breeding males and four joint-nesting females. Breeding members of the group couple promiscuously within the group, and never outside it.
It's an incestuous arrangement by human standards, with father and son competing for and breeding with the same females. And though the females use the same nests, it's pretty competitive — one female will remove and eat another mother's eggs to make room for her own. Over time, according to Hastings, this results in a balance in the number of chicks among the females.
In addition, an acorn woodpecker group will also include other, non-breeding community "helper" members — they're the woodpeckers who go into battle for acorn granaries. Though the woodpeckers primarily feed on insects, acorns provide them with non-perishable nutrition for those colder months when bug meals are few and far between.
Credit: David A Litman/Shutterstock
A granary for which an acorn woodpecker will fight is reminiscent of a human wine rack: An array of vertical storage compartments for their precious winter food. And they're dead serious about acquiring this storage: "These birds often wait for years, and when there's the right time and they have the right coalition size, they'll go and give it their all to win a really good territory," says Barve.
The balls-to-the-wall action of acorn woodpecker battle have made it difficult for human researchers to keep track of what's going on, so Barve and his colleagues devised a solution: They outfitted woodpeckers with radio tags that allowed the researchers to tell when two birds were in the same location, and to track the origin of combatants, and also to make detailed observations of a melee.
While the researchers had thought that acorn woodpeckers living nearby would most fiercely make a play for a nearby granary, this turned out not to be the case. It's not yet known what prompts one group of woodpeckers to commit to battle, though the researchers suggest that a group's internal calculus somehow produces a decision whether to try and acquire a particular granary.
Yet commit they do. The researchers found that woodpecker teams will fight for as long as 10 hours straight, and will return day after day. This was something of a surprise to researchers, making them wonder how they even sustain themselves that long.
"Get ya acorns heayah, acorns, get ya acorns heayah!"
Credit: Petr Simon/Shutterstock
Previous research missed the spectators because the brouhaha was so overwhelming and attention-grabbing. As many as 30 woodpeckers have been observed in the peanut gallery.
The researchers have seen birds coming from as far as three kilometers (1.9 miles) away. These onlookers may spend up to an hour each day in attendance. Among the spectators are woodpeckers who already have adequate granaries of their own — whatever they get out of watching has to be worth the time spent leaving their own granaries unattended. The researchers suggest the watchers may be curious about changes a battle could make to the local status quo.
These highly social birds may also actually be rooting for one fighting group over another. "They potentially have friendships," says Barve, "and they probably have enemies. The next step is to try and understand how their social networks are shaped, and how they vary across the year."
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Whether or not women think beards are sexy has to do with "moral disgust"
- A new study found that women perceive men with facial hair to be more attractive as well as physically and socially dominant.
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Beards and perceptions of masculinity<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjU5OTg0MC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0NzkxMjM3N30.cH-GqNwP5GVqvstgJWAhBPn1B_lYpVEAI0I7iax7EQw/img.jpg?width=1245&coordinates=0%2C1900%2C0%2C849&height=700" id="caae6" class="rm-shortcode" data-rm-shortcode-id="cb0a355a4e8e1899789bc45f3f7aef56" data-rm-shortcode-name="rebelmouse-image" />
Photo Credit: Wikimedia<p>The study used 919 American (mostly white) women ages 18-70 who rated 30 pictures of men they were shown with various stages of facial hair growth. The photographs depicted men with faces that had been digitally altered to look more feminine or more masculine, with a beard and without a beard. The women rated the men according to perceived attractiveness for long-term and short-term relationships. The study found that the more facial hair the men had, the higher the men were rated on their attractiveness, particularly for their suitability for a long-term relationship.</p><p>Part of this might be attributed to facial masculinity — i.e. protruding brow ridge, wide cheekbones, thick jawline, and deeply set narrow eyes — which conveys information to a woman about a man's underlying health and formidability. Women tend to associate more masculine faces with physical strength and social assertiveness. It can also indicate a man with a superior immune response. The researchers suggested that their findings favoring bearded men could be due to the fact that facial hair enhances the masculine facial features on a man's face, like creating the illusion of a thicker jaw line. This could communicate direct benefits to women like resources and protection that would enhance survival among mothers and their infants. In other words, while a beard doesn't mean superior genetics in and of itself, it might be a primitive, ornamental way of saying, "Hey girl, I'm a testosterone-fueled lean, mean, pathogen fighting machine." <br></p><p>It could also be that a beard becomes its own destiny. The researchers in this study cite prior research that found that by growing a beard, men felt more masculine and had higher levels of serum testosterone, which was linked to a higher level of social dominance. They also tended to subscribe to more old-school beliefs about gender roles in their relationships with women as compared to men with clean-shaven faces.<span></span><br></p>
What does disgust have to do with beard preference?<p>Obviously, not all women dig beards. The researchers were particularly interested in what traits make a women prefer bearded men over clean-shaven faces. They looked into several factors including a woman's disgust levels on various concepts, her desire to become pregnant, and her exposure to facial hair in her personal life. </p><p>According to the study, women who were not into facial hair were turned-off by potential parasites or other critters they imagined could be in the hair or skin. Women ranking high on this "ectoparasite disgust" scale might have viewed beards as a sign of poor grooming habits. However, women who ranked higher in levels of "pathogen" did find the bearded men to be desirable, possibly because they perceived beards as a signal of good health and immune function. An intriguing discovery in the study was links to morality. Women who displayed higher levels of "moral disgust," or feelings of repugnance toward taboo behaviors, were more likely to prefer hairy faces. The authors opined that this could reflect a link between beardedness, politically conservative outlooks, and traditional views regarding performances of masculinity in heterosexual relationships.</p>
Additional findings<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjU5OTg1My9vcmlnaW4uZ2lmIiwiZXhwaXJlc19hdCI6MTYyNDI1NjUyOX0.P9B8WbmJR0q4nfzYZKbuNSA-2SAigVWJgrQE-_Gxlds/img.gif?width=980" id="49143" class="rm-shortcode" data-rm-shortcode-id="2ed3b1d6f20fc170bf2974646e565e8d" data-rm-shortcode-name="rebelmouse-image" />Giphy<p>The correlations that existed between married and single women's rating on the attractiveness of beards were not particularly clear, although the researchers noted that single and married women who wanted children tended to find beards more attractive than the women who didn't want children. They also found that women with bearded husbands found beards to be more attractive, which might indicate that social exposure to beards influences how desirable they are perceived of as being. Or it could be that men with wives who like beards grow beards.</p><p>It's important to note that culture plays a huge role in how attractive women perceive certain male characteristics as being. This study looked at a small, culturally specific group of American women, so no big, universal claims should be made about masculinity, facial hair, and male desirability to women. However, research like this is important in highlighting how human grooming decisions are driven by much more than fashion trends. Sociobiological, economic, and ecological factors all play a part in the way we choose to present ourselves.</p>
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