Abstract
BackgroundThe development of satellite tracking technology enables the gathering of huge amounts of accurate data on animal movements over measured time intervals, to reveal essential information about species’ patterns of spatial use. This information is especially important in optimizing the design of conservation and management strategies for endangered species. In this study, we analysed the main drivers of daily patterns in the flight activity of the threatened Bearded Vulture Gypaetus barbatus. We studied 19 Bearded Vultures tagged with solar-powered GPS transmitters from 2006 to 2016 in the Pyrenees (Spain). We assessed the relative influence of external factors (season and daylight time) and internal factors (sex, breeding season and territorial status) on their daily activity behaviour by computing mean hourly distance travelled, maximum displacement and cumulative distance travelled per hour.ResultsOur findings showed a clear difference in all the estimators between territorial and non-territorial (floating) members of the population, showing that non-territorial individuals spent much longer in flight and travelled larger distances per day. We detected an important influence of daylight time and season on the daily rhythms of Bearded Vultures; flight activity increased during the last three quarters of daylight and was greatest in the spring. Breeding period and sex had also an effect on the maximum displacement and cumulative distance travelled. Individuals flew more during the breeding period and females tended to exhibit greater cumulative and maximum distances per hour than males regardless of breeding season.ConclusionsPyrenean Bearded Vultures flight daily activity was strongly influenced by daylight time, season, and territorial status, while individual sex and breeding season showed a milder effect on the birds’ movement behaviour. This study gives a novel insight into how external factors act as main drivers of the daily flight activity pattern of a long-lived avian scavenger.
Highlights
The development of satellite tracking technology enables the gathering of huge amounts of accurate data on animal movements over measured time intervals, to reveal essential information about species’ patterns of spatial use
We studied differences in the daily movement parameters according to three internal factors: sex, breeding season, and territorial status; and two external factors: daylight time and season
The records were—according to sex—34.1% females and 65.9% males and—in terms of the age class and territorial status—86.6% adults, 11.3% were from subadults, 2.0% were from immatures, and 0.1% were from juveniles
Summary
The development of satellite tracking technology enables the gathering of huge amounts of accurate data on animal movements over measured time intervals, to reveal essential information about species’ patterns of spatial use. This information is especially important in optimizing the design of conservation and management strategies for endangered species. Due to the ephemeral occurrence and random distribution of carcasses, vultures have evolved adaptive traits to exploit carrion as effectively as possible [20,21,22] The balance between their maximization of food intake and minimization of energy expenditure has developed to determine the daily foraging movements of scavenging species [23, 24]. External factors are mainly characterized by weather conditions and—both of which generally change seasonally—[4, 28], food availability [20], and intra- or interspecific interactions [20]
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