Monday, May 18, 2009

Regime Change At The Feeder, And Big Tangent On Cheating Females

OK, back safe and sound from my desert panzer attack, it’s time to catch up on what’s been happening at the Watcher Suburban Stead. Back at the end of March, when I talked about goals for year 2 of the project, I highlighted paying more attention to, and better understanding local birds.

LB4 Last May, 3 male Lazuli Buntings showed up at our feeder. I checked them out, ID’d them, thought “hey cool”, did a post on them. Then one day I noticed they were gone, and I didn’t see them again for the rest of the year.

This year, I’m paying attention. Today, May 18, marks 23 days since 3 male Lazuli Buntings showed up in our yard. Yes 3, again. The same 3? Who knows, but it’s cool to think that the same 3 birds went all the way to Central America over the winter and then found their way back to my house…

LB3 In their first week, the 3 Lazuli males effected a complete Feeder Regime Change, overthrowing the Pine Siskin Junta which had so thoroughly dominated our feeders for roughly 4 months. (The Spotted Towhee that visited briefly stood up to them as well, but he was only a transient, staying less than a week.) Although the Siskins are still resident, they’re largely been relegated to just a single feeder, and no longer tangle with the Lazuli-3.

Siskin Pack Tangent: This is a good time to mention that Bird Whisperer has repeated his bird-touching trick with the Siskins (pic right) 3 times in the last month, on one of those occasions holding the tail while it tried to flap away for 3 or 4 seconds (I’m embarrassed to admit- he was showing off for a friend. Hey, the kid’s nine…) Alas, I have yet to capture the stunt on video, but will sure to post when I do.

The Siskins and House Finches are the only birds he’s pulled this trick off with; they’re far more relaxed around people than any other bird in our yard (except maybe Gambel Quail.) The Lazuli-3, for all their ferocity with other birds, won’t let one of us approach within 15 feet.

F LB1 And to be correct it’s not the Lazuli-3, it’s the Lazuli-5 or Lazuli-6; I’m not sure, but there are either 2 or 3 females (pic left) here as well. I didn’t recognize the females last year, like the females of so many bird species, they look like… little brown birds. We’ll come back to this in a moment.

Feeder Fight1 But it’s the males who aggressively take on other birds; I’ve yet to see the females tangle with anyone. Here’s a (blurry) action shot (pic right) of a male going at it with a White-Crowned Sparrow at their favored feeder.

Tangent: Strangely, there’s one bird they seem to tolerate no problem- the male European House Sparrow (pic left) who showed up in the last month. It regularly feeds at their favored feeder, alongside Lazuli males and females alike, and they never bother it. EH Sparrow2 Why the Lazuli-3 tolerate this guy is a mystery; I’ve only come up with 2 possible hypotheses. First is that the Siskins, and WC Sparrows, and other birds the Lazuli-3 represent some threat or competition that the EH Sparrow does not. It can’t be simple food competition; the EH Sparrow is chowing down at their feeder all the time. The second (and I suspect likelier) is that because the EH Sparrow is an exotic, only having lived in the Western US for around a century, the Lazulis aren’t used to it and don’t recognize it as a threat/enemy.

Nested Tangent: The obvious third possibility, that the 2 species have some kind of mutually beneficial symbiotic thing going on, I discounted since any such symbiosis would have to have evolved in only several decades, which seems awfully short…

The Lazulis are such easy and fun birds to keep track of because they’re so darn good-looking, easily the best-looking bird we’ve laid eyes on since Costa Rica. But it’s only the males who are lookers; as I mentioned a moment ago, the females are rather brown, drab and uninteresting look at. And the same is true for so many birds we’ve looked at- Red-Wing Blackbirds, Western Tanagers, House Finches- even the male Brown-Headed Cowbird is more interesting-looking than the female. These birds all illustrate a common “rule” in songbirds; in species in which the male has bright, showy plumage, the male does not assist with incubating the eggs. The “rule” has exceptions; one we looked at last year was the Black-Headed Grosbeak.

This brings up the whole issue of why so many male birds have bright plumage, and the generally accepted idea is that it’s some sort of fitness indicator, in that a male who can grow bright showy feathers is in good health, free from parasites, and this indicates good genes, making him a more attractive suitor.IMG_9855 Presumably females who select brightly-colored males leave behind slightly more descendants, who in turn are likelier to be brighter-colored males and females who prefer them. In some cases, such as the Western Tanager, House Finch and Cassin’s Finch, the red pigment is not produced by the bird itself, but rather gained from foods eaten, so in this case would be an indication of the bird’s ability to forage effectively.

Females don’t have the bright plumage because they spend large amounts of time stationary in a nest, where they don’t want to attract attention.

Tangent: The showy males/drab female thing, so common in birds, seems pretty rare in mammals. Of course in many mammals, males are “showy” in other ways, such as a Lion’s Mane or the sheer size of a male Elephant Seal. But the comparison that really makes you stop and think is with humans.

Humans, like many, many species of birds, tend to be serial monogamists who cheat. The monogamy part is obvious, and if you think about it so is the serial part. If you’re married, there’s a pretty good chance that your current spouse isn’t your first and last spouse, and even if so, then certainly you have many friends and associates who’ve been- or will be- married more than once. Birth_Certificate1 The “cheating” part needs a bit more clarification. Most indications are that in most modern societies, most spouses don’t cheat. But in all societies some spouses do cheat. One of the most interesting- though most controversial- indicators of cheating among humans is the so-called non-paternity rate, or percentage of children in a society whose biological father is not the guy on their birth certificate. In most modern Western societies, the non-paternity rate is assumed to be around 5%*.

*But this is way controversial and the rate is way uncertain.

Anyway, the reason I bring this up is that this is exactly the deal with so many birds. They’re monogamous, but often only for a season, and they cheat, and if fact lots of studies have been done on non-paternity rates in birds, including the example I mentioned in this post of the Red-Wing Blackbird.

*Not a perfect example, as that bird is polygynous.

Nested Tangent: The real interesting thing about cheating in birds and humans is that the same evolutionary drivers would seem to be behind the behavior in both cases. For males, the evolutionary logic is easy to see: a one-time, non-committed mating has little cost, and huge potential gain- an offspring raised and cared for by another male. This doesn’t mean that male birds or humans think this when they cheat; it just means that male birds and humans who do cheat tend, on average, to leave behind slightly more offspring than non-cheaters, who in turn pass on those “cheating” genes.

For female birds and humans, the evolutionary driver doesn’t seem obvious at first: a one-time, non-committed mating has huge cost, including vulnerability to illness or predators, having to raise hatchlings/a baby without assistance, and a long period of time (~4+ years for a hunter-gather human female) during which she’s passed up other- potentially safer and more successful- mating opportunities. Why would any female bird or human ever cheat?

unh I know, I know, because her husband is unkind, he just takes her for granted, never brings her flowers, or… no, no, no. I’m not talking about the individual “why” of a given cheating scenario; I’m talking about why evolution would ever favor a cheating female. And since some portion of human females have always cheated, presumably there is some benefit.

Think it through- female birds and humans are courted. Because mating represents such a high investment for a female, they’re much pickier about with whom they mate. (The “easy” Buntings and hominids presumably didn’t leave behind too many offspring to reach adulthood…) Courting males- avian or human- try to prove that they’re the best possible potential mate for a given female, and when the female selects/accepts a mate, the unspoken premise is that she’s accepted that suitor as the best potential mate.

barack-obama-2 Actually, that’s not right. She’s accepted the suitor as the best potential mate she can get. Think about it- not every girl gets to marry Barack Obama or Antonio Banderas, and the same is true with birds. So a female bird or human mates with let’s say- the equivalent of, oh, I don’t know… how about Steve Buscemi*? Antonio-Banderas And Steve Buscemi commits to partner and raise and provide for hatchlings with the female. But then one day, Steve is at work/off foraging, and Barack or Antonio stops by. buscemi If the female mates with Barack/Antonio, but fools Steve, she can still have Steve raise her hatchlings, only now the hatchlings will have the Grade A Barack/Antonio genes, which in turn will make them more desirable mates and… pretty soon you can see how females who indulge in furtive matings with Grade A Barack/Antonio males might start to leave behind more offspring than non-cheaters…

*Really Shelley, I am not just bringing him up again just to jerk your chain… well maybe a little…

OK, but that wasn’t my point. The point I was trying to get to is this: If birds and humans have such similar mating schema, how come with birds the males are super-showy, whereas with humans, it’s the females? Yes, appearance is important for men, but female beauty is prized and valued much more highly in every human culture. Women suffer far more effort, time, inconvenience and expense for appearance than men. Why?

An astute reader might say, hey well it’s a cultural thing- women wear nice clothes and spend more time on their hair and wear cosmetics, but that’s all cultural stuff, unlike plumage. LT Woman But then you have breasts. There are at least a dozen theories behind the evolution of human female breasts; I’ve read a number of them, and they all sound like a stretch. But what do I know? Well, I know that they’re way bigger than they need to be to nurse infants, and that men overwhelmingly take notice of them. Sounds like plumage to me. Anyway, the point is why did we turn out this way- with showy women and drab men? Why not the other way around?

RW BB1 While the Lazuli-3 has asserted dominance in the backyard feeders, the male Red-Wing Blackbird (lousy pic left, sorry it was the best I could get) who showed up 5 weeks ago has firmly established a territory which encompasses our cul-de-sac, and seems to be headquartered at our neighbor’s front-yard feeder.

RWBB Map I love the sound of his calls. A friend a couple of miles away who’s an avid birder says that she never has them in her yard, and she thinks the reason is our proximity to water, specifically Emigration Creek. RW Blackbirds favor marches and wetlands, and those are the best areas to look for them.

Rat1 Tangent: Our proximity to water has a downside. This guy (pic right) has been appearing in our backyard of late. We had rats visit the backyard when we first moved in several years ago, and eliminated them with traps. After a long hiatus one has reappeared. It appears we’ll have to deal with the issue again.

Mourning Dove One more bird that’s always common around the valley, but is super-vocal now is this guy, the Mourning Dove, Zenaida macroura, (pic left) easily recognizable with his distinctive 4-part coo. Z. macroura is one of 7 Zenaida species, all of which are native to the New World, and generally all look kind of Mourning Dove-ish. Zenaida Doves are possibly the most closely-related living things to the now-extinct Passenger Pigeon. Since the Juncos departed, these birds are the most common on the ground below the feeders.

Mourning Doves are interesting to me because they’re the one bird that I hear both in my yard as well as one backpacking trips down in Southern Utah canyons. One of the reasons they do so well down in canyon country is that they can drink water from brackish springs at up to half the salinity of seawater.

OK then, that catches us up on the birds in the ‘hood. But I did a lot more than sit around the yard and look at birds this weekend, and I’ll try to get to that tomorrow.


KanyonKris said...

The bird talk was good, but the breasts = plumage tangent was a doozy. I'd say more but my wife reads your blog and the "in the name of science" argument doesn't work. I'll just mention that women generally dress (and other beautifications) to impress other women, not men.

Watcher said...

>my wife reads your blog

I knew I liked your wife!

Yes I've heard the dress-to-impress-other-women argument, but I don't think it really undermines the comparison. Even if human females are "impressing" (i.e. competing with) other human females, they're ultimately competing in terms of their attractiveness to the opposite sex. And regardless of the (conscious) motivator, they're still the non-visually-drab sex, the opposite of songbirds.

Moving beyond fashion/culture, (and I'll try to keep it clean here for Mrs. Kanyon) it seems hard to see an evolutionary benefit in impressing other women by evolving larger breasts...

WheelDancer said...

Well, keeping this as delicate as I can, it seems common that men have a certain amount of pride and bragging associated with the size of their endowment which is largely (couldn't resist...) not so much as seen by those to whom they boast and, at least in heterosexual relationships, of no benefit to the other men. Yet the boasting persists.

So wouldn't it follow that female plumage size would also play into the same-gender one upswomanship?

Watcher said...

WD- well now you’re coming back around to the issue I keep meaning to get around to blogging about one of these days which is that whole male genitalia and cycling thing. One of the key issues in that post (if I ever do it) will be size of the items involved (humans’ are abnormally large, as are chimpanzees’- far larger than needed to achieve reproductive function), for which there are at least as many theories as there are concerning how human female breasts evolved. In either case, just “one-upping” the same sex isn’t really an explanation because it doesn’t explain how the feature would lead the possessor to leave behind more fertile offspring who reach sexual maturity.

Now what you didn’t say (but might well have thought) and would be a very interesting objection is this: (Mrs. Kanyon: stop reading here) if the size of human male genitalia is the end result of selection driven by female preference, then it could be considered the human analog of “plumage” and a case could be made that males were the showy sex.

But the evidence doesn’t support it. Human females don’t seem to rate that feature highly in potential mates (not when compared with other attributes), nor seek to view it with anywhere near the effort expended by human males to view female breasts and other body parts, which is why the consumers of pornography and patrons of strip clubs are overwhelmingly male.

Anonymous said...


Okay, so I got a little lost with the whole breast and plumage and male genitalia discussion, but it sounds like you're saying that if I marry Steve Buscemi, President Obama will stop by my yard for a milkshake. Where do I sign up?


KristenT said...

Today I've got male and female house finches at the office birdfeeder, and just a few minutes ago I spotted a male American goldfinch, scoping out the offerings.

My buddy the black-cap chickadee stopped by a while ago and I've been hearing the dark-eyed juncos all afternoon!

Chuck the Squirrel hasn't been back since I opened the window this morning-- he doesn't like it when the window moves, and don't worry, I've got a screen.

Bird feeders are wonderful things, eh?

Oh, and I think you have mentioned Antonio Banderas here not so much to illustrate a point but to get more traffic off The Great Google. Very sly, sir!

Great post, as always...