In this paper we show how many fixes are enough to define the territory of two long-lived resident raptors marked by GPS transmitters. To this end, we analyzed high-resolution GPS data from 50 territorial Bonelli's eagles (Aquila fasciata) and 9 territorial Golden eagles (Aquila chrysaetos) equipped with GPS/GSM dataloggers. Our results show that between 2200 and 2800 fixes are enough to define the territory. This is interesting for movement ecology works where long-term GPS data series are not available.

ContextMovement ecology contributes valuable information about animal interactions with the environment, and their responses to landscape-level anthropogenic impacts. Big cats are vulnerable to such changes, but the current deficit of information about home range movements, limits the scope of conservation initiatives. Objectives Describe the home range size, interactions, and differences between jaguar populations across its distribution in MexicoMethodsWe used 41,008 GPS-generated data points obtained from 28 tagged jaguars (Panthera onca) in five different states of Mexico over an 18-year period to describe home range size, differences between male and female territories, interactions in overlapping territories, and territory differences among populations. ResultsOur data shows that jaguar home range is smaller than tiger’s but larger than leopard’s. Male mean home range size (285.28 km2, n=13) tends to be larger than that of females (152.2 km2, n = 15), the difference was not statistically significant. While the home range for at least one male was 633.44 km2, contrasted with the much smaller 48.89 km2 for some female jaguars. Data of overlapping ranges showed 34.71% of female territory overlaps male territory, 32.46% of female territory is shared with other females, 18.97% of male territory is shared with other males, and only 16.89% male territory overlaps with female territory. ConclusionsThe absence of significant differences in home range sizes among the habitats suggest jaguar territory is not highly dependent on the type of habitat it occupies. Our findings of the spatial parameters of jaguar movements can be applied to identifying ecological corridors and the design of protected areas for this species.

High-resolution GPS/GSM dataloggers provide spatial information of the highest quality, which outperform previous tracking methods, such as Argos telemetry or conventional VHF ground-tracking. As a result, this has improved our knowledge of home-range behavior and spatial ecology of many species, including large raptors. In this paper, we use high-resolution GPS/GSM dataloggers to assess the home-range size and the role of sex, season (breeding or non-breeding season), and breeding status (reproductive or non-reproductive individuals) on the space use of Bonelli’s eagle (Aquila fasciata). To this end, 51 territorial individuals (25 females and 26 males) were equipped with GPS/GSM transmitters and were tracked over 7 years (2015–2021) in eastern Spain. Overall, we recorded 4,791,080 fixes that were analyzed through kernel density methods (50%, 75%, and 95% fixed kernels). The average individual home-range size according to the 95%, 75%, and 50% kernels was 54.84 ± 20.78 km2, 24.30 ± 10.18 km2, and 11.17 ± 4.90 km2, respectively. Overall, the home-range size of individuals occupying the same territory was similar, mainly due to the cooperative hunting behavior exhibited by the species. We did not find interannual differences in the home-range size (95% fixed kernel) of the majority of individuals, showing a strong territorial fidelity of the breeding pairs. In general, females’ home-range size was slightly smaller than males’ size due to the decrease in activity in the breeding season as a result of laying, incubation, and chick attendance at nests. No seasonal variation in the 95% kernel was found, but it was found in the 75% and 50% kernels. In regard to the breeding status, higher home-range size was recorded in the non-reproductive individuals. Moreover, we found a low neighbor overlap among the territories (4.18% ± 3.06%), which evidences a high level of intraspecific competition in the Bonelli’s eagle. Finally, this study highlights the advantages of the use of accurate telemetry information to improve our understanding of the spatial ecology of the endangered Bonelli’s eagle, which ultimately will serve to better inform management actions for its conservation.

Coloniality is one of the most common strategies in birds. While the lesser kestrel (Falco naumanni) is a colonial raptor during the breeding period, it is not known whether individuals from the same breeding colony aggregate during the non-breeding period too. We GPS-tracked 40 adult lesser kestrels from different Spanish breeding colonies to study the degree of spatial aggregation between individuals from the same breeding colony in their West African non-breeding range. Lesser kestrels in our study used a large area from a wide longitudinal strip in the western Sahel: individuals used 143,697 plus/minus 98,048 km2 on average during the entire non-breeding period (95% KDE), and 1,359 plus/minus 1,424 km2 per week. On the other hand, the individuals traveled 6205 plus/minus 2407 km on average during the entire non-breeding period, and 41.1 plus/minus 11.8 km per day. There were no differences between the sexes in any of those variables. Individuals from the same breeding colony were not aggregated during the non-breeding period because the overlap between their areas (38.8 plus/minus 21.4 %) was not higher than that randomly expected. In conclusion, our study reveals some aspects of the non-breeding spatial ecology of the lesser kestrel, allowing a better understanding of the relationship of colonial birds out of the breeding season.

Migratory connectivity describes the linkage between breeding and non-breeding sites, having major ecological implications in birds: one season influence the success of an individual or a population in the following season. Most studies on migratory connectivity have used large-scale approaches, often considering regional populations, but fine-scale studies are also necessary to understand colony connectivity. The lesser kestrel Falco naumanni, an insectivorous migratory raptor which form colonies during the breeding period, was considered to have strong connectivity based on regional populations. However, no small scale studies on migratory connectivity have been conducted. Therefore, we GPS-tracked 40 adult lesser kestrels from 15 different Spanish breeding colonies, estimating the overlap index between home ranges and the distance between their centroids. It was found that lesser kestrels from the same breeding colony placed their non-breeding areas at 347 ± 281 km (mean ± standard deviation) away from each other (range = 23-990), and their home ranges overlapped by 38.4 ± 23.6%. No differences between intra-colony and inter-colony metrics were found, which suggests that lesser kestrels from the same breeding cluster do not overwinter together, but they spread out and mixed independently of the colony belonging throughout the non-breeding range of the species. Ultimately, this study highlights the importance of performing connectivity studies using fine-scale approaches.