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Role of breeding and natal movements in lifetime dispersal of a forest ‐ dwelling rodent

View Article: PubMed Central - PubMed

ABSTRACT

The lifetime movements of an individual determine the gene flow and invasion potential of the species. However, sex dependence of dispersal and selective pressures driving dispersal have gained much more attention than dispersal at different life and age stages. Natal dispersal is more common than dispersal between breeding attempts, but breeding dispersal may be promoted by resource availability and competition. Here, we utilize mark–recapture data on the nest‐box population of Siberian flying squirrels to analyze lifetime dispersal patterns. Natal dispersal means the distance between the natal nest and the nest used the following year, whereas breeding movements refer to the nest site changes between breeding attempts. The movement distances observed here were comparable to distances reported earlier from radio‐telemetry studies. Breeding movements did not contribute to lifetime dispersal distance and were not related to variation in food abundance or habitat patch size. Breeding movements of males were negatively, albeit not strongly, related to male population size. In females, breeding movement activity was low and was not related to previous breeding success or to competition between females for territories. Natal philopatry was linked to apparent death of a mother; that is, we did not find evidence for mothers bequeathing territories for offspring, like observed in some other rodent species. Our results give an example of a species in which breeding movements are not driven by environmental variability or nest site quality. Different evolutionary forces often operate in natal and breeding movements, and our study supports the view that juveniles are responsible for redistributing individuals within and between populations. This emphasizes the importance of knowledge on natal dispersal, if we want to understand consequences of movement ecology of the species at the population level.

No MeSH data available.


Lifetime movement activity in male and female flying squirrels: Year 0 indicates distance moved before first breeding (natal dispersal), year 1 indicates breeding moves observed within first breeding summer, and for years 2–7, breeding movements within a year not shown. Line for breeding movements is based on predicted mean values and dashed line for upper and lower confidence limits. There is no indication of a nonlinear relationship for years 1–7 (interaction between breeding movement distance and year; p > .05 for both sexes). The model for breeding movements (years 1–7) was not used to model natal dispersal, and figures also include the cases with only natal or breeding observations. Thus, confidence limits are lacking between 0 and 1 (difference between average values of 0 and 1–7: p < .0001 for both sexes). Circles are raw data. Y‐axis limited to 4 km for visibility; n = 8 females and 6 males had dispersal distance over 4 km, maximum observed 6.7 km
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ece32814-fig-0002: Lifetime movement activity in male and female flying squirrels: Year 0 indicates distance moved before first breeding (natal dispersal), year 1 indicates breeding moves observed within first breeding summer, and for years 2–7, breeding movements within a year not shown. Line for breeding movements is based on predicted mean values and dashed line for upper and lower confidence limits. There is no indication of a nonlinear relationship for years 1–7 (interaction between breeding movement distance and year; p > .05 for both sexes). The model for breeding movements (years 1–7) was not used to model natal dispersal, and figures also include the cases with only natal or breeding observations. Thus, confidence limits are lacking between 0 and 1 (difference between average values of 0 and 1–7: p < .0001 for both sexes). Circles are raw data. Y‐axis limited to 4 km for visibility; n = 8 females and 6 males had dispersal distance over 4 km, maximum observed 6.7 km

Mentions: For individuals tagged as juveniles, observed average (±SD) natal dispersal distances were 1,830 ± 1,390 m and 1,200 ± 1,340 m for females (n = 154) and males (n = 147), respectively (difference between sexes: F1,298 = 19, p < .0001). After the natal dispersal period, movement activity of both sexes declined, but the decline was clearer for females than for males (Figure 2). For adult females, breeding time nest site changes were on average only a few tens of meters (model predicted: 20 m; in raw data: 72 ± 130 m) with maximum of around 500–600 m between two consecutive years (Figure 2). However, there was one long‐distance move of 1,240 m (between two observations within the same summer). For males, breeding movements were around 300 m (predicted value; raw data 440 ± 430 m) with a maximum of around 2–2.5 km (difference between sexes in breeding movement distance: male = 166, female = 232; F1,331.2 = 162, p < .0001). Seven percent (31 of 449 cases) of breeding movements of adult males were longer than the average observed natal dispersal distances (1,200 m).


Role of breeding and natal movements in lifetime dispersal of a forest ‐ dwelling rodent
Lifetime movement activity in male and female flying squirrels: Year 0 indicates distance moved before first breeding (natal dispersal), year 1 indicates breeding moves observed within first breeding summer, and for years 2–7, breeding movements within a year not shown. Line for breeding movements is based on predicted mean values and dashed line for upper and lower confidence limits. There is no indication of a nonlinear relationship for years 1–7 (interaction between breeding movement distance and year; p > .05 for both sexes). The model for breeding movements (years 1–7) was not used to model natal dispersal, and figures also include the cases with only natal or breeding observations. Thus, confidence limits are lacking between 0 and 1 (difference between average values of 0 and 1–7: p < .0001 for both sexes). Circles are raw data. Y‐axis limited to 4 km for visibility; n = 8 females and 6 males had dispersal distance over 4 km, maximum observed 6.7 km
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ece32814-fig-0002: Lifetime movement activity in male and female flying squirrels: Year 0 indicates distance moved before first breeding (natal dispersal), year 1 indicates breeding moves observed within first breeding summer, and for years 2–7, breeding movements within a year not shown. Line for breeding movements is based on predicted mean values and dashed line for upper and lower confidence limits. There is no indication of a nonlinear relationship for years 1–7 (interaction between breeding movement distance and year; p > .05 for both sexes). The model for breeding movements (years 1–7) was not used to model natal dispersal, and figures also include the cases with only natal or breeding observations. Thus, confidence limits are lacking between 0 and 1 (difference between average values of 0 and 1–7: p < .0001 for both sexes). Circles are raw data. Y‐axis limited to 4 km for visibility; n = 8 females and 6 males had dispersal distance over 4 km, maximum observed 6.7 km
Mentions: For individuals tagged as juveniles, observed average (±SD) natal dispersal distances were 1,830 ± 1,390 m and 1,200 ± 1,340 m for females (n = 154) and males (n = 147), respectively (difference between sexes: F1,298 = 19, p < .0001). After the natal dispersal period, movement activity of both sexes declined, but the decline was clearer for females than for males (Figure 2). For adult females, breeding time nest site changes were on average only a few tens of meters (model predicted: 20 m; in raw data: 72 ± 130 m) with maximum of around 500–600 m between two consecutive years (Figure 2). However, there was one long‐distance move of 1,240 m (between two observations within the same summer). For males, breeding movements were around 300 m (predicted value; raw data 440 ± 430 m) with a maximum of around 2–2.5 km (difference between sexes in breeding movement distance: male = 166, female = 232; F1,331.2 = 162, p < .0001). Seven percent (31 of 449 cases) of breeding movements of adult males were longer than the average observed natal dispersal distances (1,200 m).

View Article: PubMed Central - PubMed

ABSTRACT

The lifetime movements of an individual determine the gene flow and invasion potential of the species. However, sex dependence of dispersal and selective pressures driving dispersal have gained much more attention than dispersal at different life and age stages. Natal dispersal is more common than dispersal between breeding attempts, but breeding dispersal may be promoted by resource availability and competition. Here, we utilize mark&ndash;recapture data on the nest&#8208;box population of Siberian flying squirrels to analyze lifetime dispersal patterns. Natal dispersal means the distance between the natal nest and the nest used the following year, whereas breeding movements refer to the nest site changes between breeding attempts. The movement distances observed here were comparable to distances reported earlier from radio&#8208;telemetry studies. Breeding movements did not contribute to lifetime dispersal distance and were not related to variation in food abundance or habitat patch size. Breeding movements of males were negatively, albeit not strongly, related to male population size. In females, breeding movement activity was low and was not related to previous breeding success or to competition between females for territories. Natal philopatry was linked to apparent death of a mother; that is, we did not find evidence for mothers bequeathing territories for offspring, like observed in some other rodent species. Our results give an example of a species in which breeding movements are not driven by environmental variability or nest site quality. Different evolutionary forces often operate in natal and breeding movements, and our study supports the view that juveniles are responsible for redistributing individuals within and between populations. This emphasizes the importance of knowledge on natal dispersal, if we want to understand consequences of movement ecology of the species at the population level.

No MeSH data available.