Home range characteristics of the Near Threatened Giant Conebill Oreomanes fraseri in fragmented Polylepis forest

Summary The Giant Conebill Oreomanes fraseri is a specialist of high Andean Polylepis forest remnants.With the aid of radio-tracking and visual observations, the average 100% minimum convex poly-gon home range size of seven adult individuals was 7.15 ha. Range size decreased with increasingtree density, and for equal tree densities, it was larger in the study site with larger Polylepis frag-ments. Home ranges often comprised areas that were largely or entirely devoid of trees. Withinhome ranges, space use significantly varied with time of day, and this pattern tended to be largelyconsistent among days. Given the large extent of variation in size and structure already observedin this small sample of home ranges, we suggest that apart from the size, shape, structure and degreeof isolation of the remaining forest patches, also t heir topographic location, and hence sun exposure,may be an important consideration when designing conservation strategies for Giant Conebill. Introduction Forest fragmentation ranks among the most important drivers of the decline of bird populationsworldwide (Renjifo 1999), and its impact depends both on the degree of loss, deterioration andisolation of the remaining habitat and on the level of habitat specialization and mobility of thebird species involved (Andre´n1994, Brown and Sullivan 2005). A decline in population size andreduced exchange of individuals in small, isolated fragments may result in increased levels ofdemographic and genetic stochasticity (Lande 1988, Turner 1996). This, in turn, may reduce thelong-term viability of populations (Lande 1988). In addition, habitat fragmentation may alsoaffect home range properties and habitat use by individual birds (Andreassen et al. 1998, Rolando2002). Whether or not habitat fragmentation affects habitat use depends on its spatial scale, inparticular the relationship between fragment size and home range size (Andreassen et al. 1998).Organisms can thereby show three possible responses to habitat fragmentation, based on theirintrinsic space requirements and social behaviour. A fusion response is expected from socialindividuals when fragment size is reduced, with smaller home ranges and increased home rangeoverlap. Home ranges of territorial organisms show less overlap, but are also reduced if the sizeof the habitat patch is close to their minimum space requirement (fission response). If habitatpatches become too small to contain individual home ranges, home ranges will expand to includemore than one habitat patch (expansion response; Ims et al. 1993). Next to fragment size, habitatquality within a fragment may affect home range size in the way that smaller home ranges canbe found in better habitat (Doster and James 1998). Furthermore, habitat quality, and foodavailability in particular, may strongly affect habitat selection and movement patterns (Rolando2002, Santos et al. 2008).