Nightingales in space: song and extra-territorial forays of radio tagged song birds

Abstract

Most temperate zone passerines defend territories during the breeding season. Commonly the size of these territories is estimated by plotting the singing locations of the males. However, an individual's activities need not be restricted to the area used for singing. So far, only little quantitative information has been available to determine how the singing territory relates to the activity range of male songbirds. Here, we present a study in which we used radio-tracking techniques to collect quantitative data on the spatial behaviour of 11 male territorial Nightingales (Luscinia megarhynchos). The results show that the singing territories made up only about 50 % of the activity ranges. Nevertheless, males spent over 90 % of the time within the singing territory. Singing territories almost never overlapped but activity ranges overlapped in all cases with the activity range of at least one neighbour. Males intruded into neighbouring territories throughout the season but the longest excursions were made before and during the female fertile period. The time spent for forays correlated significantly with song rate and territories of males with higher song rates in turn were less frequently the object of forays by other males. Song rate can be indicative of male quality, so that our findings strongly suggest that foray behaviour is related to male quality in nightingales.

Size of Territories and Home Ranges of Male Western Yellow-breasted Chats (<em>Icteria virens auricollis</em>) in British Columbia

“…By plotting observations of chat in southern Indiana, the mean territory size was 1.2 ha (SD 0.51, range 0.4-2.4) (Thompson and Nolan 1973); in Virginia, the territory size ranged from 0.5 to 1.0 ha (Dennis 1958); while in southern Illinois, the mean territory size of 0.13 ha (range 0.06-0.29) (Brewer 1955) was smaller. Our findings are consistent with other studies which reported that territory size defined through territory mapping (observations of males singing and perching) may be an underestimate of ter ritory size (the area used) (e.g., Naguib et al 2001;Anich et al 2009). …”

“…Home ranges as determined by radio-tracking often overlapped, suggesting forays outside of a male's singing territory were most likely for reasons other than expanding his territory. These forays into neighbouring territories may be for foraging, extrapair copulations, to test a neighbour's attention, or to investigate a neighbour's breeding stage (Naguib et al 2001). Extra-pair paternity commonly occurs in Western Yellow-breasted Chats in the south Okanagan (Mino et al 2011), and forays into neighbouring territories possibly involve extra-pair copulations with neighbouring females.…”

“…The use of space by a species is important for understanding its ecology (Anich et al 2009), the function of a singing territory (Naguib et al 2001), and the social relationships among conspecifics (Catchpole and Slater 1995). In the case of species at risk, this information is necessary in order to be able to map habitat necessary for protection (Anderson 2001;Clark et al 2002).…”

“…Territory mapping (defined by observations of males singing and perching) may underestimate the size of the area that is required, especially for secretive species (Anich et al 2009). However, radio-telemetry is a reliable way to obtain information about movements outside of a male's singing territory and to measure area accurately (Naguib et al 2001;Anich et al 2009. ) This is the case for a population of the Western Yellow-breasted Chat (Icteria virens auricollis).…”

Dispersal in male ursine colobus monkeys (Colobus vellerosus): influence of age, rank and contact with other groups on dispersal decisions

“…Alpha males appear to be displaying their strength, testing the competitiveness of resident male(s), and perhaps trying to entice females to transfer to their group (Watts, 1994;Steenbeek, 1999). Indeed, in some species, males of greater quality perform more and suffer fewer incursions (e.g., mammals: P. thomasi, Steenbeek, 1999; birds: Luscinia megarhychos, Naguib et al, 2001; Geothlypis trichas, Pedersen et al, 2006). These encounters must necessarily be brief however, as alpha males could lose the females in their own group and put their own infants in danger if they are gone long from their group.…”