1. Dispersal is a key mechanism enabling species to adjust their geographic range to rapid global change. However, dispersal is costly and environmental modifications are likely to modify the cost-benefit balance of individual dispersal decisions, for example, by decreasing functional connectivity. 2. Dispersal costs occur during departure, transience and settlement, and are levied in terms of energy, risk, time and lost opportunity, potentially influencing individual fitness. However, to the best of our knowledge, no study has yet quantified the energetic costs of dispersal across the dispersal period by comparing dispersing and philopatric individuals in the wild.3. Here, we employed animal-born bio-loggers on a relatively large sample (N = 105) of juvenile roe deer to estimate energy expenditure indexed using the vector of dynamic body acceleration (VeDBA) and mobility (distance travelled) in an intensively monitored population in the south west of France. We predicted that energy expenditure would be higher in dispersers compared to philopatric individuals. We expected costs to be i/ particularly high during transience, ii/ especially high in the more fragmented areas of the landscape, and iii/ concentrated during the night to avoid disturbance caused by human activity. 4. There were no differences in energy expenditure between dispersers and philopatric individuals during the pre-dispersal phase. However, dispersers expended around 22% more energy and travelled around 63% further per day than philopatric individuals during transience. Differences in energy expenditure were much less pronounced during the settlement phase. The costs of transience were almost uniquely confined to the dawn period, when dispersers spent 23% more energy and travelled 112% further than philopatric individuals. Finally, the energetic costs of transience per unit time and the total distance travelled to locate a suitable settlement range were higher in areas of high road density. 5. Our results provide strong support for the hypothesis that natal dispersal is energetically costly and indicate that transience is the most costly part of the process, particularly in fragmented landscapes. Further work is required to link dispersal costs with fitness components so as to understand the likely outcome of further environmental modifications on the evolution of dispersal behaviour.
Data for the relation between activity and accelerometry
This file contains daily VeDBAactivity data and daily VeDBAaccelerometry data, collected in the field for the first analysis “VeDBAactivity as an index of energy expenditure”. Columns: 1: individual identity/ 2: daily VeDBA activity values/ 3: daily VeDBA accelerometry values.
Daily_activity_daily_accelerometry_data_Analysis1.csv
Data for the variation of daily activity during dispersal phases
This file contains daily VeDBA activity data, collected in the field for the second analysis “Daily energy expenditure of dispersing vs. philopatric individuals”. Columns: 1: individual identity/ 2: daily VeDBA activity values/ 3: sex of individuals (M for male and F for female)/ 4: dispersal status of individuals (D for dispersers and P for philopatric individuals)/ 5: dispersal phase (pre_disp for Pre-dispersal, disp for Transience and post_disp for Post-dispersal)/ 6: year.
Daily_activity_data_Analysis2.csv
Data for the variation of daily mobility during dispersal phases
This file contains daily mobility data, collected in the field for the third analysis “Daily mobility of dispersing vs. philopatric individuals”. Columns: 1: individual identity/ 2: daily mobility values/ 3: sex of individuals (M for male and F for female)/ 4: dispersal status of individuals (D for dispersers and P for philopatric individuals)/ 5: days around the median date of transience/ 6: year.
Daily_mobility_data_Analysis3.csv
Data for the variation of the circadian rhythm of activity during dispersal phases
The circadian rhythm of dispersal and of its energetic costs”. Columns: 1: individual identity/ 2: hourly activity values/ 3: sex of individuals (M for male and F for female)/ 4: dispersal status of individuals (D for dispersers and P for philopatric individuals)/ 5: dispersal phase (pre_disp for Pre-dispersal, disp for Transience and post_disp for Post-dispersal)/ 6: hour of the day/ 7: year
Hourly_activity_data_Analysis4.csv
Data for the variation of the circadian rhythm of mobility during dispersal phases
This file contains hourly mobility data, collected in the field for the fourth analysis “The circadian rhythm of dispersal and of its energetic costs”. Columns: 1: individual identity/ 2: hourly mobility values/ 3: sex of individuals (M for male and F for female)/ 4: dispersal status of individuals (D for dispersers and P for philopatric individuals)/ 5: dispersal phase (pre_disp for Pre-dispersal, disp for Transience and post_disp for Post-dispersal)/ 6: hour of the day/ 7: year.
Hourly_mobility_data_Analysis4.csv
Data for the variation of daily activity during the transience according landscape fragmentation
This file contains daily VeDBA activity data of dispersers during the transience phase, collected in the field for the fifth analysis “The influence of landscape fragmentation on the energetic costs of dispersal transience”. Columns: 1: individual identity/ 2: daily VeDBA activity values during the transience/ 3: sex of individuals (M for male and F for female)/ 4: proportion of roads in the landscape/ 5: proportion of buildings in the landscape/ 6: proportion of woodland in the landscape/ 7: year.
Daily_activity_transience_data_Analysis5.csv
Data for the variation of total distance of dispersal during the transience according landscape fragmentation
This file contains total dispersal distance data of dispersers during the transience phase, collected in the field for the fifth analysis “The influence of landscape fragmentation on the energetic costs of dispersal transience”. Columns: 1: individual identity / 2: total dispersal distance values/ 3: sex of individuals (M for male and F for female)/ 4: proportion of roads in the landscape/ 5: proportion of buildings in the landscape/ 6: proportion of woodland in the landscape/ 7: year.
Dispersal_distance_transience_data_Analysis5.csv