Olfactory Sensitivity of the Turkey Vulture (Cathartes aura) to Three Carrion-associated Odorants

Abstract

The Turkey Vulture (Cathartes aura) is generally thought to rely on olfactory cues to locate carrion. Because vertically rising odorants are dispersed rapidly by wind turbulence, we predict that Turkey Vultures should be highly sensitive to these chemicals to detect them at foraging altitudes. Olfactory thresholds to three by-products of animal decomposition (1× 10-6 M for butanoic acid and ethanethiol, and 1× 10-5-5 M for trimethylamine) were determined from heart-rate responses. These relatively high thresholds indicate that these odorants are probably not cues for foraging Turkey Vultures. Odorant thresholds, food habits of Turkey Vultures, and the theoretical properties of odorant dispersion cast some doubt on the general importance of olfaction in food location by this species.

Olfactory enrichment and scent cue associative learning in captive birds of prey

“…Despite our taxonomic diversity and admittedly small sample sizes, in general the subjects in this study were able to learn an association between a biologically novel scent and food presence. This study implies that some of these birds of prey species may rely on olfaction for cuing foraging decisions, also a consistent finding in previous avian experimental studies (Hutchison & Wenzel, ; Houston, ; Michelsen, ; Smith & Paselk, ). Scent enrichment in feeding, and potentially in other contexts is inexpensive, safe, and easy to use in captivity.…”

“…Even with the small sample size available in the zoo collection, there was a suggestion for different intensities of wrapped package‐manipulations across the different bird species (Figure ), with vultures manipulating packages more extensively than the eagles. Carrion eaters (in our case vultures and a condor) would be expected to attend more closely to scent than the eagles, which are visual hunters (del Hoyo, Elliott, & Sargatal, ; Houston, ; Smith & Paselk, ). Furthermore, over the course of the scent training phase, the vultures typically tore apart each food package fully, generally focusing on the food‐containing/scented bundle, and left the sham package completely untouched.…”

Olfaction in birds: a closer look at the kiwi (Apterygidae)

“…To date, olfactory thresholds have only been measured in a few species of birds. Results show that the birds’ range of sensitivity to odours is similar to values obtained for mammals such as rats and rabbits (Stattleman et al 1975, Snyder and Peterson 1979, Smith and Paselk 1986, Walker et al 1986, reviewed by Waldvogel 1989 and Clark et al 1993). In more recent times, researchers have searched the avian genome for the presence and extent of olfactory receptor (OR) genes (Leibovici et al 1996, Nef et al 1996, Gray and Hurst 1998, Niimura and Nei 2005, Steiger et al 2008, 2009a) which are associated to odorant detection in vertebrates.…”

The perfume of reproduction in birds: Chemosignaling in avian social life

“…Second, some avian groups were shown to possess acute olfactory capabilities, used for foraging or orientation (see Roper, 1999 for review). Nevertheless, research was restricted to the responses of a few species (vultures, kiwis, pigeons, and procellariiform seabirds) to environmental cues only (Benham, 1906; Benvenuti et al, 1977; Grubb, 1972; Papi et al, 1974; Shallenberger, 1975; Smith and Paselk, 1986; Stager, 1967; Wenzel, 1968). …”