Modelling habitat selection of Common Cranes Grus grus wintering in Portugal using multiple logistic regression

Abstract

Predictive models of habitat suitability for the Common Crane Grus grus in a wintering area of southern Portugal were derived using logistic multiple regression and Geographic Information Systems. The study area was characterized by landscape variables and surveyed uniformly for the presence of cranes. The most important variables were distance to roosts, to open Holm Oak woods and to villages, and the occurrence of unpaved roads, shrubby vegetation, slope and orchards. Two models were built, the second having one variable fewer than the first. The selection of the best model was based on statistical and biological criteria. Crane distribution was negatively related to: distance to open Holm Oak Quercus rotundifolia woods and roosts. Additionally, unsuitable vegetation and orchard areas are avoided. In these areas movement is difficult, food availability is reduced and the risk of predation increased. We also found that villages and roads were avoided; disturbance is a significant factor for this species. Some management guidelines are proposed for the area: (1) maintenance of open Holm Oak woodlands, (2) incentives to avoid the abandonment of traditional agriculture and pastoral use of the area, which would lead to an increase of shrubby vegetation areas, (3) preservation of suitable roosting places and (4) management of new patches of forest and orchards

Agriculture—a key element for conservation in the developing world

“…Species such as Asian crested ibis ( Nipponia nippon ) have benefited from long historical associations with traditional arable agriculture. Numerous crane species forage on agricultural land benefiting from spilt cereal grains (Table 1), similar to the use of farmland by common crane ( Grus grus ) in Europe (Franco et al . 2000).…”

“…Species such as Asian crested ibis (Nipponia nippon) have benefited from long historical associations with traditional arable agriculture. Numerous crane species forage on agricultural land benefiting from spilt cereal grains (Table 1), similar to the use of farmland by common crane (Grus grus) in Europe (Franco et al 2000). In Asia, remaining areas of low-to-medium intensity rice cultivation provide stubbles that support wintering granivorous passerines, such as yellow-breasted bunting (Emberiza aureola).…”

Beyond bioclimatic envelopes: dynamic species' range and abundance modelling in the context of climatic change

“…Where the data product has a finer grain than that of the model, habitat availability within each model cell can be quantified (Hill et al 2001). At the opposite extreme, complex niche models may include many habitat dimensions (Catling et al 1998, Franco et al 2000). Such models may be fitted using many different approaches, some more appropriate in their assumptions than others (Austin 2007).…”

Obtaining Environmental Favourability Functions from Logistic Regression

“…Logistic regression has shown to be a powerful tool that produces robust models, and it is broadly used in the predictive modelling of species' distributions starting from presence/absence data (e.g. Romero and Real 1996;Bustamante 1997;Franco et al 2000;Madsen and Prang 2001;Seoane and Bustamante 2001). …”