Factors affecting the responses of female Canada Geese to disturbance during incubation

Abstract

During incubation, Canada Geese (Branta canadensis) and other waterfowl flush from their nests in response to the approach of potential predators and subsequently return to nests after the threat of predation has abated. Differences among individuals in their responses to such disturbance (e.g., how close a potential predator approaches before flushing) are thought to reflect variation in female age, the reproductive value of clutches, and nest site characteristics. From 26 April to 26 May 2010, we examined the possible effects of these factors on the behavior of female Canada Geese (B. c. interior) on Akimiski Island, Nunavut. We used humans as surrogate predators and flushing distance and return time after disturbance as response variables. The distance at which females flushed in response to approaching humans was best explained by the density of vegetation around nests, with females on better concealed nests flushing at closer distances. We also found a weak relationship between return time and clutch size, with females with larger clutches returning to nests sooner. The frequency of human visits did not affect either female flushing distance or return time. Female Canada Geese in our study appeared to minimize risk of their own injury or death (future reproductive potential) in escape decisions, whereas return times appeared to minimize the risk of nest predation (current reproductive investment).

Drivers of within- and among-individual variation in risk-taking behaviour during reproduction in a long-lived bird

“…Females breeding in concealed nests displayed shorter FIDs. This confirms previous evidence that well-hidden prey in sheltered habitats tolerate a closer approach before fleeing [28,52,[89][90][91][92], including eiders [93]. However, there is ongoing debate on whether individuals adjust their behaviour according to their local environment [94], or settle in habitats providing the best match to their behavioural profile ('personality-matching hypothesis' [95]), or phenotype in general [32].…”

State dependence explains individual variation in nest defence behaviour in a long‐lived bird

“…FID is defined as the number of paces between the observer and the female at the moment the female goose flees of her nest, during a straight and slow walking approach of the observer towards the nest (see for similar methodology; e.g. Miller et al., 2013; Osiejuk & Kuczyński, 2007; Quillfeldt et al., 2005; Sjöberg, 1994). Most females walked or ran off their nest, only in some cases (usually when they bred on the edge of an island) they flew off and landed in the water.…”

Escape Distance in Ground-Nesting Birds Differs with Individual Level of Camouflage

“…Blumstein 2006; Møller 2010), we assessed escape behaviour by using an approaching human as a proxy for a predatory threat, and measured the distance at which the bird fled its nest. In nesting birds, escape distances are known to be related to degree of concealment through vegetation cover (Klvan et al 2004;Miller et al 2013), as well as stage of egg development (Osiejuk and Mickiewicz 2007), and colonial versus solitary breeding (Šálek and Cepáková 2006). However, to our knowledge the present study is the first to investigate escape behaviour in relation to directly quantified camouflage, as seen by the visual systems of relevant predators.…”