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Spatio-temporal hotspots of satellite-tracked arctic foxes reveal a large detection range in a mammalian predator.

Lai S, Bêty J, Berteaux D - Mov Ecol (2015)

Bottom Line: The scale at which animals perceive their environment is a strong fitness determinant, yet few empirical estimates of animal detection ranges exist, especially in mammalian predators.Using daily Argos satellite tracking of 26 adult arctic foxes (Vulpes lagopus) during a single winter in the High Canadian Arctic, we investigated the detection range of arctic foxes by detecting hotspots of fox activity on the sea ice.Foxes often traveled more than 10 km, and up to 40 km, to reach hotspots, which lasted one-two weeks and could gather up to 12 individuals.

View Article: PubMed Central - PubMed

Affiliation: Canada Research Chair on Northern Biodiversity, Centre for Northern Studies and Quebec Center for Biodiversity Science, Université du Québec à Rimouski, 300 Allée des Ursulines, Rimouski, QC G5L 3A1 Canada.

ABSTRACT

Background: The scale at which animals perceive their environment is a strong fitness determinant, yet few empirical estimates of animal detection ranges exist, especially in mammalian predators. Using daily Argos satellite tracking of 26 adult arctic foxes (Vulpes lagopus) during a single winter in the High Canadian Arctic, we investigated the detection range of arctic foxes by detecting hotspots of fox activity on the sea ice.

Results: While maintaining territories in the tundra, these solitary foragers occasionally used the sea ice where they sometimes formed spatio-temporal hotspots, likely scavenging on marine mammal carcasses. We detected 35 movements by 13 individuals forming five hotspots. Foxes often traveled more than 10 km, and up to 40 km, to reach hotspots, which lasted one-two weeks and could gather up to 12 individuals. The likelihood of a fox joining a hotspot was neither influenced by its distance from the hotspot nor by the distance of its home range to the coast.

Conclusions: Observed traveling distances may indicate a high detection range in arctic foxes, and our results suggest their ability to detect food sources on the sea ice from their terrestrial home range. While revealing a wide knowledge gap regarding resource detection abilities in mammalian predators, our study provides estimates of detection range useful for interpreting and modeling animal movements. It also allows a better understanding of foraging behavior and navigation capacity in terrestrial predators.

No MeSH data available.


Related in: MedlinePlus

Estimated population–level use of the sea ice by arctic foxes using dynamic Brownian bridge movement models. Estimations for the month of a December, b January and c February, with black arrows indicating the spatio–temporal hotspots detected on the sea ice of Navy Board Inlet (Nunavut, Canada) during winter 2010–2011. The 25, 50, 75 and 99 % cumulative probability contours are shown in blue, with the darkest shades indicating the highest probabilities. Areas where more than 3 foxes occurred are delimited by a red line. Individual home ranges on Bylot Island are delimited by black lines. d Estimation for the month of November, when no hotspot was detected (shown for reference). Note that the coastline can appear as a relatively highly used area due to the back-and-forth crossing of foxes from their inland range to the sea ice, and to the home ranges located along the coast
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Fig1: Estimated population–level use of the sea ice by arctic foxes using dynamic Brownian bridge movement models. Estimations for the month of a December, b January and c February, with black arrows indicating the spatio–temporal hotspots detected on the sea ice of Navy Board Inlet (Nunavut, Canada) during winter 2010–2011. The 25, 50, 75 and 99 % cumulative probability contours are shown in blue, with the darkest shades indicating the highest probabilities. Areas where more than 3 foxes occurred are delimited by a red line. Individual home ranges on Bylot Island are delimited by black lines. d Estimation for the month of November, when no hotspot was detected (shown for reference). Note that the coastline can appear as a relatively highly used area due to the back-and-forth crossing of foxes from their inland range to the sea ice, and to the home ranges located along the coast

Mentions: We delineated the inland home range of each individual by calculating the dBBMM UD using locations on land and extracted the 50 % cumulative probability contours (core areas, Fig. 1). We then used dBBMMs to locate areas on the sea ice used intensively by foxes. Since the sea ice period covered more than 7 months, we divided it into smaller periods of 30 days to analyze sets of fox locations that were rather aggregated temporally. We used time slices of 30 days because carrion in cold climates can sometimes remain for at least a month during winter [12, 41]. Starting from 25 October 2010, we used a time window of 30 days moved in 2–week increments, so that time slices overlapped with each other. For each time slice, we calculated the dBBMM UD for each individual. We then summed the cell values of all individual UDs in order to obtain the population–level UD [42, 43]. Although arctic foxes can scavenge on and gather around terrestrial mammal carrion, such as caribou (Rangifer tarandus) or muskox (Ovibos moschatus) carcasses, we did not expect scavenging on land since there are no large herbivores in the study area. To facilitate visualization of the UD of the sea ice, we thus substracted ad hoc all land cell probabilities and re–scaled the resulting UD so that it summed to 1. One fox using repeatedly the same area sometimes led to high cell values in the population–level UD. In addition, pair mates foraging on the sea ice close to their home ranges also yielded high cell values along the coast (see Fig. 1d). For these reasons, we also calculated how many of the individual 75 % UDs (corresponding to the moderate to high–use areas) occurred within each cell of the population–level UD [43]. Resulting cell values ranged from 1 to n, with n ≤ the total number of individuals present during the analyzed time slice [43]. Finally, we identified highly–used areas visited by several foxes (“hotspots”), by selecting cells used by ≥ three foxes (Fig. 1).Fig. 1


Spatio-temporal hotspots of satellite-tracked arctic foxes reveal a large detection range in a mammalian predator.

Lai S, Bêty J, Berteaux D - Mov Ecol (2015)

Estimated population–level use of the sea ice by arctic foxes using dynamic Brownian bridge movement models. Estimations for the month of a December, b January and c February, with black arrows indicating the spatio–temporal hotspots detected on the sea ice of Navy Board Inlet (Nunavut, Canada) during winter 2010–2011. The 25, 50, 75 and 99 % cumulative probability contours are shown in blue, with the darkest shades indicating the highest probabilities. Areas where more than 3 foxes occurred are delimited by a red line. Individual home ranges on Bylot Island are delimited by black lines. d Estimation for the month of November, when no hotspot was detected (shown for reference). Note that the coastline can appear as a relatively highly used area due to the back-and-forth crossing of foxes from their inland range to the sea ice, and to the home ranges located along the coast
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4644628&req=5

Fig1: Estimated population–level use of the sea ice by arctic foxes using dynamic Brownian bridge movement models. Estimations for the month of a December, b January and c February, with black arrows indicating the spatio–temporal hotspots detected on the sea ice of Navy Board Inlet (Nunavut, Canada) during winter 2010–2011. The 25, 50, 75 and 99 % cumulative probability contours are shown in blue, with the darkest shades indicating the highest probabilities. Areas where more than 3 foxes occurred are delimited by a red line. Individual home ranges on Bylot Island are delimited by black lines. d Estimation for the month of November, when no hotspot was detected (shown for reference). Note that the coastline can appear as a relatively highly used area due to the back-and-forth crossing of foxes from their inland range to the sea ice, and to the home ranges located along the coast
Mentions: We delineated the inland home range of each individual by calculating the dBBMM UD using locations on land and extracted the 50 % cumulative probability contours (core areas, Fig. 1). We then used dBBMMs to locate areas on the sea ice used intensively by foxes. Since the sea ice period covered more than 7 months, we divided it into smaller periods of 30 days to analyze sets of fox locations that were rather aggregated temporally. We used time slices of 30 days because carrion in cold climates can sometimes remain for at least a month during winter [12, 41]. Starting from 25 October 2010, we used a time window of 30 days moved in 2–week increments, so that time slices overlapped with each other. For each time slice, we calculated the dBBMM UD for each individual. We then summed the cell values of all individual UDs in order to obtain the population–level UD [42, 43]. Although arctic foxes can scavenge on and gather around terrestrial mammal carrion, such as caribou (Rangifer tarandus) or muskox (Ovibos moschatus) carcasses, we did not expect scavenging on land since there are no large herbivores in the study area. To facilitate visualization of the UD of the sea ice, we thus substracted ad hoc all land cell probabilities and re–scaled the resulting UD so that it summed to 1. One fox using repeatedly the same area sometimes led to high cell values in the population–level UD. In addition, pair mates foraging on the sea ice close to their home ranges also yielded high cell values along the coast (see Fig. 1d). For these reasons, we also calculated how many of the individual 75 % UDs (corresponding to the moderate to high–use areas) occurred within each cell of the population–level UD [43]. Resulting cell values ranged from 1 to n, with n ≤ the total number of individuals present during the analyzed time slice [43]. Finally, we identified highly–used areas visited by several foxes (“hotspots”), by selecting cells used by ≥ three foxes (Fig. 1).Fig. 1

Bottom Line: The scale at which animals perceive their environment is a strong fitness determinant, yet few empirical estimates of animal detection ranges exist, especially in mammalian predators.Using daily Argos satellite tracking of 26 adult arctic foxes (Vulpes lagopus) during a single winter in the High Canadian Arctic, we investigated the detection range of arctic foxes by detecting hotspots of fox activity on the sea ice.Foxes often traveled more than 10 km, and up to 40 km, to reach hotspots, which lasted one-two weeks and could gather up to 12 individuals.

View Article: PubMed Central - PubMed

Affiliation: Canada Research Chair on Northern Biodiversity, Centre for Northern Studies and Quebec Center for Biodiversity Science, Université du Québec à Rimouski, 300 Allée des Ursulines, Rimouski, QC G5L 3A1 Canada.

ABSTRACT

Background: The scale at which animals perceive their environment is a strong fitness determinant, yet few empirical estimates of animal detection ranges exist, especially in mammalian predators. Using daily Argos satellite tracking of 26 adult arctic foxes (Vulpes lagopus) during a single winter in the High Canadian Arctic, we investigated the detection range of arctic foxes by detecting hotspots of fox activity on the sea ice.

Results: While maintaining territories in the tundra, these solitary foragers occasionally used the sea ice where they sometimes formed spatio-temporal hotspots, likely scavenging on marine mammal carcasses. We detected 35 movements by 13 individuals forming five hotspots. Foxes often traveled more than 10 km, and up to 40 km, to reach hotspots, which lasted one-two weeks and could gather up to 12 individuals. The likelihood of a fox joining a hotspot was neither influenced by its distance from the hotspot nor by the distance of its home range to the coast.

Conclusions: Observed traveling distances may indicate a high detection range in arctic foxes, and our results suggest their ability to detect food sources on the sea ice from their terrestrial home range. While revealing a wide knowledge gap regarding resource detection abilities in mammalian predators, our study provides estimates of detection range useful for interpreting and modeling animal movements. It also allows a better understanding of foraging behavior and navigation capacity in terrestrial predators.

No MeSH data available.


Related in: MedlinePlus