Morphological Description of American Crow, <em>Corvus brachyrhynchos</em>, Populations in Southern Quebec

Abstract

The American Crow has always been a much scrutinized bird in North America but, since the emergence of West Nile Virus (WNV) in North America in 1999, public health authorities’ attention to it has been raised another notch. In Québec, like everywhere else in North America, part of the WNV surveillance programme was based on detection of WNV mortality in crow populations. During the summer of the 2005 surveillance season, we followed an age and gender determination protocol, as well as a morphological measurement protocol, on dead crows sent in for WNV status determination, to improve our knowledge of the crow population in Québec. Statistical analysis of the measurements revealed that age and gender were important factors in the morphological characterisation of the American Crow. Bill depth and head-to-bill length appeared as the most important morphological variables for gender prediction through a discriminant function analysis. We also realized that, in adult age groups, our WNV positive carcasses had lower mean weights than carcasses that tested negative for WNV, in adult age groups.Depuis toujours, la corneille d’Amérique est un oiseau très étudié, mais, depuis l’apparition du virus du Nil occidental (VNO) en Amérique du Nord en 1999, l’attention des autorités en santé publique sur cet oiseau a encore augmenté. Au Québec, comme ailleurs en Amérique du Nord, une part importante du programme de surveillance pour la détection du VNO a été basée sur la détection des mortalités liées au VNO dans les populations de corneilles. Pour améliorer notre connaissance de cette espèce au Québec, nous avons mis à profit la récolte des carcasses au cours de l’été 2005 dans le cadre du programme de surveillance en instaurant un protocole de détermination de l’âge, du genre ainsi qu’une prise des mesures morphologiques sur ces mêmes carcasses. L’analyse statistique des résultats a montré qu’à la fois l’âge et le genre étaient des facteurs importants dans la caractérisation morphologique de la corneille d’Amérique. À l’aide de l’analyse discriminante, il est apparu que la profondeur du bec ainsi que la distance tête-bec étaient les mesures les plus importantes pour prédire le genre de l’oiseau. Nos analyses nous ont également permis d’observer que, dans les groupes d’oiseaux adultes, les carcasses positives pour le VNO étaient en moyenne moins lourdes que les carcasses négatives.

Acoustic profiling in a complexly social species, the American crow: caws encode information on caller sex, identity and behavioural context

“…This level of sex classification accuracy was relatively low, compared to that achieved in other studies (65 - 100%) using a combination of body size metrics measured from birds in the hand (Clark, James, and Morari 1991; Yaremych et al 2004; Ludwig, Begras-Poulin, and Lair 2009). It is also lower than that achieved by a prior study on this population (87% non-cross-validated, excluding one particularly atypical male), using the acoustic properties of single alarm caws (Yorzinski et al 2006).…”

Social and Spatial Reintegration Success of New Caledonian Crows (Corvus moneduloides) Released after Aviary Confinement

“…NCCs could see those birds in adjacent cages. Individuals of Corvus species can be roughly aged from the color of the oral mucosa (lining of the mouth; Ludwig et al 2009). One of the 13 NCCs was a first-year juvenile (pink mouth), five were aged 2 years or older (mottled pink and black mouth), and five were adults (black mouth) ( Table 1).…”

Genetic divergences and intraspecific variation in corvids of the genus Corvus (Aves: Passeriformes: Corvidae) - a first survey based on museum specimens

“…Body size varies between 120 g in C. monedula / dauuricus and 2000 g in C. corax , the largest of all passerines. Sex dimorphism does not occur in many species but is pronounced in some (Ludwig et al. 2009).…”

“…Body size varies between 120 g in C. monedula ⁄ dauuricus and 2000 g in C. corax, the largest of all passerines. Sex dimorphism does not occur in many species but is pronounced in some (Ludwig et al 2009). Their omnivorous life style allowed the representatives of Corvus to live in any habitat type, from closed primary rain forest up to semi-open habitats and deserts.…”