Foraging ovenbird follows Armadillo

I report an observation of a foraging Ovenbird (Seiurus aurocapillus) following a ninebanded armadillo (Dasypus novemcinctus), near Gainesville, Florida. Close attendance only while the armadillo was moving and disturbing leaf litter suggests the Ovenbird was taking advantage of increased prey availability caused by the armadillo's flushing of insects. Received 27 May 1998, accepted I Oct. 1998. Many species of birds forage in association with groups of other species. The two most common explanations of such interspecific groups relate to decreased risk of predation and increased foraging efficiency (Bertram 1978). Foraging efficiency can be increased via several mechanisms (Morse 1970). Perhaps the least-well studied mechanism occurs when one species follows another species and captures prey incidentally flushed by the second species. Such a relationship between "followers" and "beaters" has been reported for groups of birds and groups of cattle (Scot 1984), dolphins (Evans 1987), primates (Terborgh 1983, Boinski and Scott 1988), wolves (Silveira et al. 1997), ants (Willis and Oniki 1978), and other birds (Bennetts and Dreitz 1997). Here I report an observation of an Ovenbird (Seiurus aurocapillus) following a nine-banded armadillo (Dasypus novemcinctus). On 6 March 1998 at 10:35 EST along the rim of Paynes Prairie (Alachua County, Florida), I flushed an Ovenbird from the ground. After perching for 1-2 min, it flew to the ground within 3 m of an armadillo. As the armadillo started to move forward, the Ovenbird flew directly to it, landing approximately 30 cm from its tail and maintaining that distance of separation as the armadillo walked. I followed them for 17 min at a distance of 10-12 m. The armadillo often stopped briefly (< 10 s) to dig or push its snout into the leaf litter. The Ovenbird did not approach the armadillo's head during these times but rather remained by its tail. On two occasions the armadillo stopped for 1-2 min and the Ovenbird walked 2-3 m away from it. When the armadillo started to move again, the Ovenbird immediately resumed following it, once returning by flight. It frequently pecked at the leaf litter. I was unable to determine if these presumed foraging attempts were successful. They did not appear more frequent when the Ovenbird was following close behind the armadillo than when it temporarily foraged by itself. I did not notice any insects being flushed by the armadillo, but there was heavy shade and I lacked binoculars. I stopped my observation when the armadillo walked into a clearing and the Ovenbird did not follow. The behavior of the Ovenbird suggests its association with the armadillo was not due to both animals being attracted to an area of high prey abundance. In particular, its close proximity to the armadillo only when the armadillo was moving suggests it was using the armadillo as a beater. A similar pattern of attendance has been noted for Double-toothed Kites (Harpagus didentatus), Gray-headed Tanagers (Eucometis pencillata), and Tawnywinged Woodcreepers (Dendrocincla anabatina) following Squirrel Monkey (Saimiri oerstedi) troops; attendance frequencies of these species were higher when the Squirrel Monkey troops were moving and foraging than when they were immobile (Boinski and Scott 1988). Despite high levels of disturbance created by armadillos while foraging, I am unaware of any other published accounts of birds following them. Further observations are required before it can be concluded that the bird I watched was not idiosyncratic and that Ovenbirds benefit from following armadillos. ' Dept. of Zoology, PO Box 118525, Univ. of Florida, Gainesville, FL 32611-8525; E-mail: DLEVEY@zoo.ufl. edu This content downloaded from 207.46. 13.71 on Sat, 22 Oct 2016 05:37:00 UTC All use subject to http://about.jstor. org/terms 444 THE WILSON BULLETIN * Vol. 111, No. 3, September /999