Influence of moult and location on patterns of daily movement by Egyptian Geese in South Africa

Abstract

Abstract. The daily movements of 18 Egyptian Geese (Alopochen aegyptiaca) in South Africa were recorded using satellite telemetry. General additive mixed models were used to explain the distances moved by the birds at different times of the day, correcting for sex, site, season and individual. Distances moved by birds in the mesic, winter-rainfall, south-western region (Strandfontein) of South Africa were compared with movements in the semi-arid, summer-rainfall region (Barberspan) of northern South Africa. Moulting birds all remained at single wetlands during moult, displayed crepuscular patterns of activity and nocturnal retreats to safety. At the end of moult, birds dispersed away from moulting sites. The longest daily distances travelled by individuals took place mainly just before moult was due to start or within the first 10 days after completing moult, providing strong evidence that Egyptian Geese undertake moult migrations. The daily pattern of movement was strongly skewed, with >70% of flights being short (<10 km) and longer flights mainly occurring at night (88%). There were considerable differences in patterns of dispersal between birds at the summer-rainfall site and the winterrainfall one. Summer-rainfall birds undertook long-distance movements between wetlands whereas Winter-rainfall birds appeared to move randomly and over short distances.

Movement ecology of five Afrotropical waterfowl species from Malawi, Mali and Nigeria

“…Longer-term adaptation or learning experience may be influencing their movements, including prior experience with resource distributions that effect dispersal strategies (Roshier et al 2008b;Cumming et al 2012;Ndlovu et al 2013). For example, nomadic behaviour of Knob-billed Ducks was evident from our data.…”

“…These exploratory flights allow ducks to assess wetland conditions or conspecific activity in surrounding regions before settling. However, their daily movement was only 1.5-1.9 km, in contrast with Australian Grey Teal Anas gracilis that moved 2.9-25.2 km daily (Roshier et al 2006) and Egyptian Geese Alopochen aegyptiaca in South Africa for which most daily movements (57%) were 1-10 km (Ndlovu et al 2013). Thus, Knob-billed Ducks seem to explore far less frequently than those species, which may suggest greater reliance on their experience of the area or environmental cues affecting the frequency of their flights.…”

“…Our results indicate that travel distances varied widely among the five waterfowl species that we studied, but there were key wetlands to which waterfowl have high site fidelity. Use of focal wetlands may be related to life stages when waterfowl are particularly vulnerable, such as during the moult (Ndlovu et al 2013).…”

A framework for testing assumptions about foraging scales, body mass, and niche separation using telemetry data

“…However, both species are commonly found at wetlands, and both may range far from open water to forage on agricultural fields. Both species also exhibit a relatively predictable daily movement sequence in most locations, with birds roosting overnight and foraging intensively in the morning and evening (Hockey et al., ; Ndlovu, Cumming, & Hockey, ). Their movements throughout the year can be divided into three main phases: (1) breeding, during which they are tied to a nest site and a nearby wetland until the ducklings can fly (duration around 10 to 15 weeks in total, with 4–5 weeks of incubation and 8–10 weeks for the ducklings to grow); (2) flightless molt, which involves synchronous replacement of the primaries at a deep, permanent wetland and takes 4–5 weeks every year (Milstein, ); and (3) a “roaming” period, during which the birds move around the landscape in flocks, following food resources in a seminomadic manner.…”

“…Their movements throughout the year can be divided into three main phases: (1) breeding, during which they are tied to a nest site and a nearby wetland until the ducklings can fly (duration around 10 to 15 weeks in total, with 4–5 weeks of incubation and 8–10 weeks for the ducklings to grow); (2) flightless molt, which involves synchronous replacement of the primaries at a deep, permanent wetland and takes 4–5 weeks every year (Milstein, ); and (3) a “roaming” period, during which the birds move around the landscape in flocks, following food resources in a seminomadic manner. Full analyses of the movements of both species have already been published (Cumming et al., ; Ndlovu, Cumming, Hockey, Nkosi, & Mutumi, ; Ndlovu et al., ).…”