Two Solitudes: The Behaviour of Pigeons in Competitive Feeding

Abstract

Previous research showed that pigeons foraging for preferred grains of maize and less preferred grains of wheat respond to the presence of a competitor by becoming less choosy ( i.e. they more readily choose wheat). We extended this work by disentangling the presence of the competitor from the resource depletion associated with it. In Experiment 1, eight birds foraged for maize and wheat in a flight cage. They were tested both alone and with another bird in different foraging sessions. Two groups were formed and differed in how they were treated when the birds foraged in pairs: both birds had access to food (Both Eat) versus only one bird had access to food (Only One Eats) while the other was placed behind a transparent curtain. For the latter treatment, no effect of the mere presence of the other bird on choice was found. Pigeons were, however, less choosy in the presence of a real competitor that exploited the food. At the end of the experiment, the pigeons that had been tested in the 'Both Eat' treatment, were tested in the 'Only One Eats' treatment. They behaved as if foraging alone. Experiment 2 introduced a new condition in which one bird ate and the other was placed behind the curtain where it pecked at grain but could not eat it. Even though this other bird behaved as if it were a potential competitor, it had no effect on the forager in the pair. The only significant difference in choice proportions was between birds foraging in real competition ( i.e. where the other bird caused resource depletion) or not. In competitive feeding situations, pigeons react to what is most directly associated with the dwindling food conditions but are insensitive to the presence and to the pecking behaviour of the animal that creates them.

Dietary habits of urban pigeons (Columba livia) and implications of excreta pH – a review

“…Experiments with various seeds, simulating a natural diet, showed inter-individual variability among pigeons, but noted that while peas, millet and grain were preferred, but hard-shelled maize was spurned (Brown 1969;Moon & Zeigler 1979); but see the contrary data (Plowright & Redmond 1996;Plowright et al 2004). Grain size was a factor in a number of studies with both too large (Shettleworth 1987) and too small units being rejected (Biedermann et al 2012).…”

“…Grain size was a factor in a number of studies with both too large (Shettleworth 1987) and too small units being rejected (Biedermann et al 2012). Competition by other pigeons made individuals less choosy (Plowright & Redmond 1996;Plowright et al 2004). As covered above, the wild progenitors of feral pigeons, the rock dove, are strictly granivorous, while feral pigeons are omnivores (Lefebvre & Giraldeau 1984;Jokimaki & Suhonen 1998).…”