Identifying the environmental drivers of corridors and predicting connectivity between seasonal ranges in multiple populations of Alpine ibex (Capra ibex) as tools for conserving migration

Aim

Seasonal migrations, such as those of ungulates, are particularly threatened by habitat transformations and fragmentation, climate and other environmental changes caused by anthropogenic activities. Mountain ungulate migrations are neglected because they are relatively short, although traversing heterogeneous altitudinal gradients particularly exposed to anthropogenic threats. Detecting migration routes of these species and understanding their drivers are therefore of primary importance to predict connectivity and preserve ecosystem functions and services. The populations of Alpine ibex Capra ibex have all been reintroduced from the last remnant source population. Despite a general increase in abundance and overall distribution range, ibex populations are mostly disconnected but display intra-population migrations. Therefore, its conservation is strictly linked to the interplay between external threats and related behavioural responses, including space use and migration.

Location

Austria, France, Italy and Switzerland.

Methods

By using 337 migratory tracks from 425 GPS-collared individuals from 15 Alpine ibex populations distributed across their entire range, we (i) identified the environmental drivers of movement corridors in both spring and autumn and (ii) compared the ability of a connectivity modelling algorithm to predict migratory movements between seasonal ranges of the 15 populations, using either population-specific or multipopulation datasets, and three validation procedures.

Results

Steep, south-facing, snow-free slopes were selected while high elevation changes were avoided. This revealed the importance of favourable resources and an attempt to limit energy expenditures and perceived predation risk. The abilities of the modelling methods we compared to predict migratory connectivity from the results of those movement analyses were similar.

Main Conclusions

The trade-off between energy expenditure, food and cover was the major driver of migration routes and was overall consistent among populations. Based on these findings, we provided useful connectivity models to inform conservation of Alpine ibex and its habitats, and a framework for future research investigating connectivity in migratory species.