HELL HATH NO FURY
S
o the guys fight and brawl with each other while the girls live in peace and harmony? Not bloody likely â¦
Dear Dr. Tatiana,
Â
My name's Jerome, and I'm a moorhen. I'm seriously alarmed by the violent behavior of the girls in my species: they're not babes, they're brutes. At the slightest provocation, they leap in the air and start clawing each other. Why are they so truculent, and how can I stop them from killing each other?
Â
Bring Back the Ladies in Norfolk
Don't worry: in most species, females are far too sensible to kill one another. And when they do fight to the death, it's not usually over a man but over something importantâlike a house. Even then, a fight to the death is rare. It occasionally happens in thripsâtiny black insects with wings that look like miniature feathers. In
certain Australian species, females are armed with massive front limbs and kill each other for their ideal home, a gall on an acacia tree. Queen ants can be belligerent too. In the seed-harvester ant, queens cooperate to found a colony and get it up and running: several queens can establish a colony faster than a queen working alone, and it will be less vulnerable to raids from neighbors. As soon as the colony looks like a going concern, though, the queens are at daggers drawn, tearing one another to pieces in battles for control of the nest. But in general, if you're a girl, the rewards from bumping off rivals are not worth the risk of getting killed yourself.
That doesn't mean that girls don't fight over boys at all. As anyone who's been to a girls' school can tell you, things turn nasty when boys are in short supply. Often the problem is temporary: at the start of the breeding season of the smooth newt, girl newts are hot to trot but boy newts, who have a fixed supply of sperm for the whole season, are initially reserved. The result? Bad manners. Since newts set packets of sperm on the ground, single girls barge in on courting couples to steal the sperm just as the male deposits it. But by the end of the season, most girls have lost interestâhaving mated, they are busy laying eggs, a slow process because they wrap each one in a leafâand it's the boys who quarrel over any girls who are still keen. Likewise, in the Australian katydid
Kawanaphila nartee,
an elegant twiglike creature related to crickets and grasshoppers, bachelors are in great demand early in the season. That's because these insects like to eat pollen, and in early spring most flowers haven't bloomed yet. But males woo by secreting a large meal, which they provide along with their genes, so that springtime scarcity of pollen is a double whammy: lots of hungry females eager to mate in order to dine and hardly any males who've eaten enough to be able to make lunch. Under these circumstances, when a male rubs his
stumpy wings together to announce he's prepared a meal, several females come jumping and wrestle for the right to mate. Once pollen becomes abundant, however, calm is restored. Being better fed, females are less hungry for sex even as more males are able to join the dating game.
But this is nothing. In some species, the shortage of males is chronic. For
Acraea encedon,
an African butterfly, the deficit is severe. More than 90 percent of the butterflies in some places are female. Why? They are infected with the dread disease
Wolbachia. Wolbachia
is a bacterium often found in insects; like a shape-shifting monster, it has different effects on different hosts. For these butterflies, it is King Herod, killing little boys early in their embryonic development. Where
Wolbachia
is common, male
Acraea
are rareâand females gather, chasing any butterfly they see in desperate attempts to find a mate.
The usual reason for a dearth, happily, is more benign. In some species where males help with child care, a given male cannot look after all the eggs or young that one female can produce. Ideally, then, each female would have more than one male at her disposal. But that causes shortagesâand fighting. Consider the midwife toad
Alytes muletensis,
a mottled olive and orange creature who lives in gorges on the Mediterranean island of Majorca. In the evenings, males croon love songs from hiding places in the rocks. Females who are ready to lay their eggs will answer one of the singers and then hop around to his home to make his acquaintance. If she likes the looks of him, she'll stroke him on the snoutâmidwife toad for “Let's do it, baby.” At that, he grabs her from behind. She responds by stamping in place, and he starts strumming her genitalia with his toes. They keep this upâpuncâtuated by brief pausesâfor perhaps a couple of hours, although heavy petting can go on all night. At last, the female goes into spasms and releases her eggs, each one connected to the one
before by a thin gelatinous thread, a kind of poor man's pearls. As the eggs appear, the male wraps his arms around her neck, releases sperm, and starts scissoring his legs like a demented gymnast. The point of this antic soon becomes clear: he's winding the string of eggs around his legs, where it will remain until the eggs are ready to hatch into tadpoles.
Which is why the fighting begins. Once a male has a string of eggs, he's unavailable until he's dumped the ripened eggs into a pool of water. That could take anywhere from nineteen days to two monthsâexactly how long depends on the weather, as eggs develop more slowly at lower temperatures. But females can produce a clutch every three weeks or so, and they must find a male to look after them; if they cannot, they will lose the clutch. Available males become hot items, and females are not ashamed of trying to steal someone else's guy. Females wrestle with each other or, more often, intrude on a courting couple and hug the male from behind so he can't strum properlyâin hopes that the rival female will get fed up with his lousy tap dancing.
This combinationâmales looking after young and females wanting more than one male eachâoften leads to blows. That's why I suspect the Darwin frog of having pugnacious females. This little green frog with a pointy nose, who makes its home in the leaf litter of Chilean forests, has an obscure sex life. But we do know a few salient facts. Females lay between thirty and forty eggs. Once fertilized, the eggs sit in the damp earth for about three weeks, at which point the muscular twitchings of the developing embryos stimulate males to start parental care. The form of parental care is peculiar, perhaps unique: the males swallow the eggs and brood the tadpoles in their vocal sacs. After about fifty-two days, Dad opens his mouth and, abracadabra, tiny frogs hop out. Obviously, while a male has his vocal sacs stuffed with tadpoles, he can't sing to attract more mates, so brooding is a big
commitment. Unlike the Japanese cardinal fish, a species where males brood fry in their mouths, the Darwin frog doesn't eat his children if he sees a girl sexier than his original mate. But since each male can manage only about fifteen tadpoles, a female needs two or three males per brood. Moreover, every brooding male is out of action for over seven weeks. In such a system, competition for available males must be intense.
Even when bachelors are out in droves, though, girls still scrap and bicker if some fellows are better catches than others. It's the same old story: everyone wants to marry the heir to a fortune, no one wants the poor pimply guy in the corner. This is what's going on with your female moorhens, Jerome. All the girls set their caps at the smallest, fattest fellows; no one wants the big gangly one. If the girls start fighting whenever you approach, you must be ravishingly rotund. Why the fuss over small and fat? In moorhen culture, males do most of the work of sitting on eggs. This may not sound strenuous, but it is. Males fade away as the breeding season wears on. Fat guys can keep eggs warm for longer, and females with fat fellows can produce more clutches in a season than girls with slimmer spouses. Given the difference, it's worth fighting to secure a fat mate. And small? Small males fatten up better. For moorhens, short and dumpy is in.
Dear Dr. Tatiana,
Â
I'm a burying beetle. I met my wife when we worked together at a chipmunk's funeral. It was love at first sight, and after a whirlwind romance I thought I'd found paradise. But now she's turned into a frightful harridan. Nag, nag, nag. I don't get a moment's peace, and whenever I try to relax in the evening by doing
headstands, she bites me or knocks me over. What have I done to deserve this, and how can I get her off my back?
Â
I Hate the Trouble and Strife in Ontario
Are you sure you're not trying to have your corpse and eat it too? You know as well as I do that when a male burying beetle stands on his head he exposes the tip of his abdomen and sends sexy scents wafting through the air. I suspect that when you do your headstands you're not chilling out but trying to attract a mistress. Call it a hunch, but that might be why your wife finds your behavior galling.
Look at it from her point of view. The two of you must have struggled for hours to bury that chipmunk. Chipmunks are more than two hundred times heavier than burying beetles. If you were lucky, the body was lying on soft earth so all you had to do was dig soil out from beneath it. But if the ground was hard, you would have had to move the corpse, perhaps over the astonishingly long distance of several meters, to soft ground. Once the body was at last interred and out of reach of ants and blowflies, you had to remove its fur and massage its poor dead flesh into a ball, ready to feed to your babies when they hatch and crawl onto the carcass. Lucky babies! Nothing like regurgitated rotting chipmunk to give you the start you need! Picture it: the grubs sitting in the carcass, rearing up and opening their mouths like baby birds when you or your wife chirrs and bends over to give them their lunch. It's heartwarming to think that these maggoty grubs, who now bear no resemblance to their magnificent parents, will one day sport shiny black wing covers scalloped with red just like yours.
But now you and your headstands threaten this blissful scene. Sure, a mistress would be great for youâyou would have more
children if you could lure a second female to the carcass. But it would be a disaster for your wife. The presence of another woman and her brats would make it harder for your wife to raise all of hers. This is not just because the two families would have to share the chipmunk meat and there might not be enough to go around. Rather, the mistress would probably murder (and then eat) some of your wife's children. (To be fair, though, your wife wouldn't refrain from chowing down the mistress's kidsâit's a burying-beetle-eat-burying-beetle world.)
Females of many species stand to lose if their mate takes an additional lover. Sometimes the mistress does a burying beetle and kills the wife's children. In both the house sparrow and the great reed warbler, for example, a male with two mates will help only the female whose clutch hatches first, so to ensure herself of male assistance, a savvy mistress will smash all the wife's eggs. But things are not always so grim. Often the wife loses out simply because a gallivanting male leaves her with more work than she can handle and she's not able to raise as many offspring. Or she may lose because the brats from a second liaison take food or other valuable resources away from her own children. But whatever the reason, females in many species are not interested in sharing their manâand take steps to prevent it.
As you've discovered, scolding, chivying, and harrying a fellow is one way to make sure he doesn't have time for mischief. A female pied flycatcher who catches her mate singing when he should be working isn't subtle in her disapproval, often interrupting him to make him shut up. The story is familiar: a male pied flycatcher who's trying to impress some floozy will hastily depart if he sees his angry wife bearing down on him.
Rather than raging when they feel insecure, some females mount a charm offensive. Female starlings, for example, get all lovey-dovey and constantly beg for sex if they notice their mate
courting other lasses. But whether they shower their mate with kisses or brickbats, females everywhere have the same response to girls they suspect of seducing their husbands: hostility. In the northern harrier, a bird of prey from North America, females intimidate possible rivals and attack them if they are carrying food. Female blue tits dive-bomb rivals, often knocking them out of the air. A female starling, as well as distracting her mate with canoodling, will chase a rival whenever she spots one hanging about and will sing ostentatiously to show the little tart what's what. If she finds her mate strutting his stuff at a second good nest hole, she may resort to filling it up with straw, feathers, and other material to make it look occupied, even though she has a nest of her own. A male starling often ends up chasing his wife back to her own nest to stop her beating on potential mistresses.
But he doesn't have it as bad as Mr.
Lamprologus ocellatus.
This fish lives in Lake Tanganyika, one of the Great Lakes of tropical Africa. A male holds a territory; as for many birds, a crucial feature of his territory is the nest sites that he can offerâin this case, empty snail shells. You might not think so, but there's fierce competition for preowned snail shells. Many creatures find them useful shelters. Hermit crabs famously depend on finding used snail shells: rather than growing shells of their own, they move from empty shell to empty shell as they get bigger. It's not always easy to find a shell of the right size, yet many hermit crabs are finicky, preferring to squeeze into shells that are too small rather than wear a shell of the right size that has a hole in it. And just to show how central used snail shells can be to a local community, some hydroidsâsimple animals related to jellyfish, corals, and sea anemonesâprefer to settle on shells occupied by hermit crabs. How can they tell? Hermit crabs scuttle about faster than the shell's original owner, and baby hydroids are attracted by the motion. It's mutually convenient. Hydroids have powerful venoms
that might discourage anyone in the mood for a hermit-crab sandwich. For the same reason, some hermit crabs harvest sea anemones and stick them to their shells. In return, the hydroid (or anemone) gets scraps of food and protection from its own predators, which the crab zealously fends off.