Relative avian mobility linked to use of fire-affected resources in forested landscapes
Forest Ecology and Management
Increased fire frequency is predicted in global forests over the 21st century owing to climate change. Fire–averse animals are expected to be negatively impacted by frequent wildfire events, or corresponding habitat alteration and reduction in the extent of long unburnt forest in landscapes. Mobility is an attribute that may enable bird species persistence in this context, but the capacity to move varies among species. Our aim was to determine whether birds with similar movement strategies, i.e. groups of sedentary, migratory and nomadic species, have similar patterns of occurrence in relation to forest fire frequency and long unburnt forest in the landscape. We modelled occupancy of avian movement groups and species in austral temperate forests in relation to fire frequency in forest patches and the presence/absence of long unburnt forest in the landscape surrounding each patch. We also evaluated relationships between species body size and responses to fire, because larger species tend to disperse further and have larger territories. Migrants responded positively at the group level to the presence of long unburnt forest in the landscape. No other consistent responses of movement groups to fire were detected, although foraging or nesting niche overlaps were evident among species that responded similarly to fire within groups. Of the 20% of 74 total species that responded to one or both fire history predictors, there were twice as many mobile species (migrants, nomads) than sedentary species. Positive responses to the presence of long unburnt forest were dominated by migrants and were much stronger than positive or negative responses to fire frequency. No species was more likely to occur when long unburnt forest was absent from the landscape. Species that responded to fire were large (median body mass 243 g) compared with those that did not respond (median 23 g). Our structured approach to investigating how avian movement capacity and propensity influences occurrence in relation to fire frequency has increased understanding of the mechanisms that enable avian persistence in fire-prone forests. Many large, mobile bird species can and do move at landscape scales to use resources that may be affected by fire frequency, particularly those that are embodied in long unburnt forest.
Open Access Status
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