Drivers of daily movement patterns affecting an endangered vulture flight activity

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.Electronic supplementary materialThe online version of this article (10.1186/s12898-018-0195-7) contains supplementary material, which is available to authorized users.

Habitat preferences of Southern Ground-hornbills in the Kruger National Park: implications for future conservation measures

“…However, future research should consider study designs able to account for these potential differences, as García-Jiménez et al . 26 showed that both the breeding season and sex of the individual influence displacement and distance travelled in Pyrenean Bearded Vultures ( Gypaetus barbatus ). They found that all individuals travelled more in the breeding season, with females having greater cumulative and maximum distances regardless of the season.…”

Spatial and temporal movement of the Bearded Vulture using GPS telemetry in the Himalayas of Nepal

“…So we considered a total of nine samples (bird/age‐class) in the analysis. GPS fixes were filtered to remove the overnight roosting and only fixes recorded between 05:45 and 17:45 h local time zone were used for the analysis (García‐Jiménez et al ).…”

Influence of individual biological traits on GPS fix-loss errors in wild bird tracking

“…The significant differences in FLR between male and female birds are not easily explained from a behavioural and ecological perspective (mean values of 0.32 for males cf. 0.39 for females), even if non-territorial males do indeed exploit larger areas and fly over longer distances, as it is the case of territorial females 19,20 . The specific relationships between the biological traits of this species and RPF or RFF are clear, but even if their influence on the FLR is also obvious, it is more difficult to explain the effect of certain biological variables such as territoriality or sex on FLR.…”

“…It is an endangered species now only found in certain mountainous areas of Europe, Asia, and Africa 21,41 . In the Pyrenees, the spatial ecology of this species has been studied since the 1980s' , originally using conventional VHF radio tracking [42][43][44] and more recently with the solar-powered Argos or GSM data recovery system with GPS-PTTs 19,20,45 .…”

“…Based on previous solar-powered GPS tracking studies 13,[25][26][27] , our hypothesis was that both FLR and flight activity of birds are strongly influenced either by specific biological traits and/or extrinsic factors, especially those related to technical factors. We hypothesized that individuals with greater flight activity (higher rates of fix in flight, RFF-reasonably assumed to be non-territorial individuals, who usually travel larger distances 19,20 ), would be more exposed to direct solar radiation, thus present increased battery charging, and a lower FLR compared to territorial individuals. Considering extrinsic factors, weather conditions will affect fix reception success because periods with more daylight hours (i.e.…”