House Wrens are complicated, mysterious cheaters

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I got my start in ornithology studying the love lives of House Wrens. House Wrens pair up to raise their babies in a manner compellingly analogous to the human “nuclear family;” but, like most birds, both partners also often “cheat” on each other (i.e., copulate with other birds). This means that the male wren may have chicks in other nests besides his own, and he may end up caring for chicks that are not biologically related to him. (Note: edited. The original version of this sentence had a mistake.)

This sets up a number of interesting questions, such as: why cheat on your partner? Are the chicks sired by outside birds somehow better? Do males know when they are caring for chicks who aren’t their own? The answer to the latter question seems pretty clear (no, the males do not know), but the former two are more challenging.

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This webcomic gets it

As a scientist, I can’t exactly claim to to be underserved by the webcomic community. xkcd does nerdy jokes, including ones about biologists and birds; Hark A Vagrant occasionally covers historical scientists like Rosalind Franklin and Charles Darwin (twice); and Saturday Morning Breakfast Cereal often delves into evolutionary biology, with takes ridiculousentertaining, and sometimes a bit too real.

Still, before today, I had never seen an ornithological behavioral ecology comic. (Talk about niche audiences.)

Thank you, Saturday Morning Breakfast Cereal, for filling this hole in my life.

(Original comic webpage here.)

Scarred

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Like elephants or dinosaurs, male Northern elephant seals on land are massive past the point of useful reference. A 5000-lb animal falls off our everyday mental scale; it’s just enormous.

Yet, lounging around on the sand at this time of year—their mating season—these beasts look like they need some band-aids and Neosporin. Their thick, strong hide is marred with new gashes laid over old scars. Titans they may be, but even titans can fall when they square off against other titans.

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Two males facing off. The male on the left has blood on his nose.

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Cats are in a human-made trap. It’s our duty to get them out of it.

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When I was kid, I thought I didn’t like cats. It didn’t help that every time I got near one, my eyes got itchy and my nose ran. My cat allergy disappeared around the time I went to college, where I volunteered at the local animal shelter and got a new perspective on felines. In the second year of my PhD program, I went to the East Bay SPCA and adopted a 3-year-old former stray.

I love my cat. She is 40% sweetheart, 40% terror, and 20% judgmental staring statue.

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It looks like I’m sleeping, but I am watching your every move.

I am an ecologist, an ornithologist, and a bird-lover, so I know some things about cats that a lot of cat lovers may not. It all adds up to this: humans have put cats into an ecological trap, and we continue to do so, often with the best of intentions. It is not the cats’ fault. It is our human duty to get them out of this trap, for the cats’ sakes and for wildlife.

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Happy Valentine’s Day, pigeons

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Nothing better demonstrates the axiom “familiarity breeds contempt” than the pigeon. Pigeons have remarkable navigation skills and are extremely powerful fliers. They perform courtship dances and mate for life (as much as any bird does, anyway). Both parents care for the chicks. They have an adaptation—”crop milk,” a substance that they produce and feed to their chicks, similar in concept (if not physiology) to how we mammals produce milk for our babies—that allows them to breed in habitats most birds could never hope to raise a family in. They thrive in urban environments, making them probably the first and most-often seen wild animal of many city-dwellers. They recognize each other as individuals. They are smarter than you think.

Concerning their usefulness to humans, pigeons are easily raised in captivity and edible. They have been bred into many domestic varieties with strange attributes, such as the propensity to roll over in mid-air. Charles Darwin studied domestic pigeons extensively, and they contributed to the formation of his theory of evolution by natural selection. They have been important message carriers in wartime; pigeons have received the Dickin Medal—like the Medal of Honor, but for animals—32 times, more than any other species (dogs are closing in with 31 medals).

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And they come in sparkly colors with crazy eyes.

“Rats with wings,” people say—patently untrue: you can’t get plague from pigeons. “Dirty,” people call them; as if it isn’t our dirt they are wearing, and yet thriving anyhow.

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Gooseneck barnacles and Barnacle Geese

One of the joys of biology lies in appreciating how strange and varied the world is. When humanity starts to feel claustrophobic, you can imagine the life of an albatross, aloft over the ocean for most of her life, searching out schools of delicious fish by their scent; or a cuttlefish, flashing colored signals at his companions as he shoots through the currents, flexible tentacles waving. When the world feels narrow and limiting, you can remember that clownfish change sexes depending on their place in the dominance hierarchy, with males becoming female when they advance to the position of top dog.

Yet—amazingly—biology used to be even wilder. Before satellite tracking and genetic analysis, before “biology” was a recognized science at all, natural philosophers looked at a perplexing natural world and invented some truly outside-the-box explanations for what they saw.

Some of these are fairly well known: for example, the idea that there is a “homunculus”—a tiny human—inside the head of each human sperm cell.

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As drawn by N. Hartsoeker in 1695. Public Domain, https://commons.wikimedia.org/w/index.php?curid=635170

To be fair, we now know that sperm (and eggs, etc.) contain the genetic blueprint for building a human, which isn’t all that far off from containing a tiny human.

But my favorite old science myth involves—of course!—birds.

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The pros and cons of trying to eat everything

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The noble California Gull, a diet generalist

Animals eat different things. Every kid knows about herbivores vs. carnivores. Strangely, the other type of diet variation—diet breadth—is much less generally known. Generalists have broad diets, being able to eat a wide variety of things, while specialists eat only a few types of items. Anteaters and hummingbirds are specialists; the seagull who flew off with your lunch is a generalist.

Being a generalist gives a species a lot of advantages, especially in unpredictable environments. The more you can eat, the less likely you are to run out of food. An anteater without ants will starve, but a seagull without fish can eat crabs, or carrion, or Cheetos.

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Or whatever this is.

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