Women Prefer Penguins
©1996 Gerard V. Haigh
Frantically foraging and feeding, two small birds were enslaved by a monster baby bird almost twice as big as they were. Baby was squawking out its demands almost continuously and every few minutes mama or papa would return to drop food into its gaping maw.
My friend Eric had discovered this bizarre trio in the oak grove by the pond at Trippitt Ranch during our monthly bird walk. He directed my attention to the drama being enacted high in the Coastal Live Oaks just below the canopy.
The two small birds were slim, handsome adults. They were blue-gray above and white below, had white eye rings and long black and white tails.
While they were like wrens in having the same busy way of feeding, were similar in size, and occasionally cocked their tails straight up, these were definitely not wrens. These harried and hapless victims were Blue-gray Gnatcatchers.
Gnatcatchers spend much of the year in Central America and fly up to the USA to nest and raise their young. A hazard they face in trying to accomplish this task is that they are one of the species of small birds which are frequently parasitized by the Cowbird.
The big, fat juvenile these two Gnatcatchers were so busily feeding was a Cowbird. Its mother had deposited it, inside an eggshell, in the Gnatcatcher nest. Because its incubation period was shorter and because its growth rate was faster, the young Cowbird quickly outstripped in size its Gnatcatcher siblings. When it got big enough, it muscled them out of the nest to die on the ground below. Such is the struggle for survival in the natural world, even in Topanga State Park.
Now, instead of raising five young of their own, the parent Gnatcatchers were faced with the problem of what to do with this one big fat ugly stranger. It would seem as if they might have the choice to abandon it and start over again. But do they?
Some host birds have the wisdom to discriminate a Cowbird egg when it is first laid in their nest and they throw it out. Some have apparently not mastered the technical skill to remove one bad egg from a clutch of several eggs and solve the problem by building another floor over the first set of eggs and lay another clutch. (I have found a Yellow Warbler nest which had four levels, each of the lower three having one Cowbird egg and the fourth with none.)
Once the eggs hatch, however, the host parents seem to be unable to turn away from a baby begging for food. However ugly a baby cowbird may appear to us and however unlike in appearance it may be to their own species, the victimized parents feed, feed, feed as long as the youngster demands, demands, demands. And the juvenile cowbird continues to demand until it is almost twice the size of its foster parents and goes off to join other cowbirds and feed on its own.
Surely it was not a choiceful decision for these two harried little Gnatcatchers to extend their ongoing hospitality to the uninvited guest who dropped in for dinner and stayed on, killing all of their own family so that he could get all the food for himself! It seems more likely that their willingness to nurture this unattractive and ungracious stranger must derive from a parental instinct so powerful as to over-ride all rational considerations.
In strong contrast to the apparent strength of parental instinct in the Gnatcatchers was almost the lack of any in the 'mother' Cowbird. The only mothering she did was to select a suitable family with which to abandon her offspring.
Such a weak parental instinct is rare among female birds. Only the Cowbird on this continent and the Cuckoo in Europe exhibit this trait. However, weak parental instinct is not uncommon among male birds. Our free-spirited male hummingbirds, for example, give only their sperm to the child-rearing process. After attracting a female through spectacular displays of flashing colors and daring flights, the male copulates and moves on. The female is on her own to build a nest, incubate the eggs and feed the young.
All of these patterns of parenting are found among humans. There are mothers who give up their babies for adoption though it is usually done through negotiation rather than dumping on the doorstep. Many couples are as willing as Gnatcatchers to raise someone else's child. Many men move on like hummingbirds leaving young children behind to be raised solely by the mother. We tend to think of these various behaviors as matters of choice but is it possible that they also are partly determined by differences among us in the strength of the parental instinct?
My wife, Lynne, is very fascinated with the fathering instinct of the Emperor Penguin. She loves to tell the story of how these penguins start their family in the beginning of winter in Antartica. They go inland a few miles where the female lays one egg and returns to the sea to feed. Her mate takes over the egg, puts it in a brood patch near his feet and incubates it for two months. He stands there in the dark with thousands of other males through the Antarctic winter. The temperature is below zero, the winds howl and the snow flies. Finally, the female returns just as the egg hatches and frees the male to eat again for the first time in two months. However by this time there are forty or fifty miles of ice between him and the ocean which he must cross to reach his food supply.
I am not sure why this story is so appealing to women. I suppose, if given a choice among the various parental patterns exemplified by male birds, I can understand that most women would like their mate to be more like an Emperor Penguin than like a Hummingbird.
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