Sex and the birds: 5. Rape

posted in: Heron-Egret-Bittern, Sex | 7

When female birds are unwilling partners in mating, the male may indulge in an avian form of rape.

It is common among supposedly monogamous Wood Ducks (Aix sponsa) and Mallards (Anas platyrhynchos) (Tudge, 2008). The former have been known to practice “gang rape” where as many as 50-75 males try to mate with a single female. The Mallards are just as bad, sometimes causing the female to drown when attacked in the water (above, male; below, female). It has been reported that half of all Mallards broods are the result of multiple paternity. However as most of these ducks practice “egg-dumping” that involves laying eggs in nests of others of their own species, multiple paternity does not always indicates adulterous relationship.

Eastern Cattle Egrets (Bubulcus ibis) are seasonally monogamous (below). The male establishs his territory and attracts females with his courtship displays. Once a female accepts him, she will attempt to subdue him by landing on his back. The pair will then move off to build their nest where copulation takes place LINK. Cases of rape and rape attempts have been documented by Fujioka & Yamagishi (1981) and Telfair (1994).

Many species of ducks have developed behavioural and anatomical means to control which male fathers her offspring. These have been elaborated by Yale University’s evolutionary biologist Patricia Brennan studies on duck rape LINK 1 and LINK 2. Some ducks have small pockets that develop inside the side of the tubular oviduct near its opening. These presumably function as “dead ends” or false passage for the penis. In others the oviduct develops into a tight, clockwise spiral that discourages entry of the counter clockwise spiral of the male’s penis. During normal copulation these physical barriers can easily be overcome.

About a third of duck-sex is forced. However, actual fertilisation occurs in only about 2% of forces sex.

Credit: YC Wee (text), Dr Eric Tan (Mallard image), Kowng Wai Chong (Eastern Cattle Egret image).

References:
1.
Fujioka M. & S. Yamagishi, 1981. Extramarital and pair copulations in the Cattle Egret, The Auk, 98, pp 134-144.
2. Telfair, R.C. II, 1994. Cattle egret (Bubulcus ibis). In: The birds of North America, No. 113 (A. Poole and F. Gill, Eds.). The Academy of Natural Sciences, Washington, D.C.
3. Tudge, C., 2008. Consider the birds. Who they are and what they want. Allen Lane, London. 480 pp.

7 Responses

  1. Waah! BESG is getting more & more exciting for me. It has gone sexual. I’d rather sit comfortably in my armchair drinking a beer while reading the BESG blog than go wasting my time watching birds in the forest. BESG has everything about birds (& butterflies) handed to me on a platter.
    Cheers! Keep them coming!!

  2. Lee Chiu San

    Yes, birds do get drunk, though it’s not good for them. The worst are the Parrot tribe, many of whom, besides being able to talk, often think that they are people in more ways than one. After a party one night, we went to bed without clearing up. My wife remembered leaving a glass with some dregs of Gran Marnier on the table. Next morning, the glass was dry, and our free-roaming Blue Eyed Cockatoo (Cacatua opthalmica)was unconscious on the floor. We rushed it to the veterinarian Tan Hwa Luck who resuscitated it. The bird spent the rest of that day and the next moaning and groaning and looking morose. We called the vet again. He was unsympathetic, saying that drunks act that way when they suffer from hangovers.

    I have allowed lories and lorikeets to have little sips of wine and other sweet alcoholic drinks, but will not do this again. Not only is it bad for their health, but these birds are by nature already aggressive, and tame ones have egos out of all proportion to their size. They usually become fighting drunk. Luckily, most of them are under ten inches tall.

    Back to serious discussion of the subject, under avicultural conditions, I find that most birds will only sample new drinks if these are sweet. Anecdotally, I have also heard of birds getting drunk after eating fermenting fruit, but have no actual experience of this.

    It is also a common tale that poachers capture quail and pheasants by leaving grain soaked in whisky for them to consume, but I have not known of any such cases personally.

  3. Blimey! This blog is getting more & more revealing. Send the birds over & I will share my Tiger with them. I promise not to make them drunk & dead to the World!
    Ho, ho, ho!!!

  4. Thong Chow Ngian

    I heard from an Australian friend that it is common to see drunk birds at wine yards, after feasting on fermenting rotten grapes.

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