Interspecific Cooperative Nesting between Barn Swallows and Say's Phoebes in South-Central New Mexico

Abstract

Intraspecific cooperative nesting is not a common event in the avian world, although it is well documented in species like the Acorn Woodpecker (Melanerpes formicivorus; Koenig et al. 1984) and Common Moorhen (Gallinula chloropus; Gibbons 1986). Intraspecific cooperative nesting occurs when more than two birds of the same species take part in providing parental care to rear the young (Emlen and Vehrencamp 1983). Our purpose is to document an observation of interspecific cooperative nesting between a pair of Barn Swallows (Hirundo rustica) and a Say's Phoebe (Sayornis saya). We have found no published records that document interspecific cooperative nesting in birds. This event is even more unusual in that Say's Phoebes often usurp Barn Swallow nests (Bent 1942). In late March 1993, a pair of Say's Phoebes built a nest atop an old Barn Swallow nest at our housing facilities at the Orogrande base camp on the Fort Bliss Military Reservation. The nest was located at the juncture of two steel girders supporting the roof. Orogrande is located in south-central New Mexico, approximately 96 km north of El Paso, Texas. Adjacent habitat is Chihuahuan Desert scrub (Shreve 1942) and desert grassland (Budd et al. 1979). After fledging one of three young in late April, the phoebes left the general area and were observed occasionally foraging from surrounding poles and utility wires. A short time after the phoebe fledged, Barn Swallows began to occupy and restore other nearby swallow nests with no apparent interest in the phoebe nest. On 13 June, we observed Barn Swallows lining the phoebe nest with feathers. Barn Swallows commonly line their nests with feathers, but phoebes do not (Terres 1991). On 15 June, we discovered a Barn Swallow egg in the phoebe nest. Because nest reuse occasionally occurs in birds (Butler 1980, Butler and Campbell 1987, Shields et al. 1988), the fact that the Barn Swallows were using the phoebe nest did not appear odd. However, later that same day, a Say's Phoebe was observed on the nest. We checked the nest using a mirror and saw that a Barn Swallow egg