Factors affecting movements and home ranges in the jay (Garrulus glandarius)

Abstract

The winter home ranges, movements and density of the jay Garrulus glandarius in the Maremma Natural Park (Tuscany, Italy) are presented, and compared with those already known for the other seasons. The movements of jays were studied for short periods over 6 years by radiotelemetric techniques (26 home ranges), direct observations of movements from vantage points, and transect counts. Summer and autumn ranges were much larger than spring and winter ones. Incremental area plots and auto-overlap analyses showed that, on average, spring ranges increased in area with time without shifting, whereas winter ranges were rather stable. In both periods, however, some birds moved as¯oaters since the degree of range autooverlap decreased signi®cantly with time. In winter and spring, range sizes of jays inhabiting different habitats were signi®cantly different, being larger in sites with higher habitat heterogeneity. The structure of home ranges was variable in all seasons; birds showed jointed and disjointed ranges, with one or more activity centres, in all the possible combinations. In every season the average degree of range overlap between jays caught at the same site was rather high and overall actual overlap, when non-tagged birds were also considered, was even higher. No territorial behaviour was ever observed. During summer jays moved into the pinewood for the greater part of the day to collect cicadas, Cicada orni, and returned to the maquis in the evening. During autumn birds regularly moved within the maquis or from the maquis to the pinewood to cache oak (Quercus ilex) acorns. No regular long movements between habitats were observed during spring and winter. Direct observations and analyses of pellets suggested that food was abundant and highly diversi®ed throughout the year. Thus, seasonal movements and home ranges were¯exible and mainly controlled by food availability and its distribution in space and time.

Spatial patterns in long‐distance dispersal ofQuercus ilexacorns by jays in a heterogeneous landscape

“…In contrast, jays dispersed most of the acorns to pine stands, whether afforestation or open pinewoods. This tendency to move acorns outside oak stands has been observed for European jays in other places (Patterson et al 1991, Kollmann and Schill 1996, Rolando 1998) as well as for other jay species (Johnson et al 1997), and it is presumably a strategy to decrease the risk of intraspecific kleptobiosis and secondary predation (Bossema 1979, Vander Wall 2001, Emery and Clayton 2001). Buried holm‐oak acorns in Mediterranean woodlands are consumed mainly by two mammals species, the wild boar Sus scrofa and the woodmouse Apodemus sylvaticus (Focardi et al 2000, Gómez et al 2001a, Gómez 2003).…”

“…Second, birds could try to avoid open sites to decrease their own risk of being preyed upon by hawks and mammalian carnivores, as has been observed in other places (e.g. Rolando 1998). Third, the most probable cause of caching acorns under pines is because it decreases the probability of postdispersal predation by some mammals like wild boars and rodents that use these microhabitats less intensely when searching for acorns (Gómez 2003).…”

Synzoochory: the ecological and evolutionary relevance of a dual interaction

“…The spatial structure of vegetation, both at local and landscape scales, may also determine the proportion of seeds cached versus eaten (Puerta‐Piñero et al, ; Yang & Yi, ; Puerta‐Piñero, Pino & Gómez, ; Castro et al ., ; Morán‐López et al ., , b ; Aliyu et al ., ). For example, the proportion of seed effectively dispersed by Eurasian jays is significantly influenced by the presence of pine woodlands and afforestation (Rolando, ; Gómez, ; Pons & Pausas, ; Sheffer et al ., ; Pesendorfer et al ., ). In summary, the variable effect of granivores on plant fitness is not only context‐dependent but also depends on intrinsic features of the interacting organisms.…”

Mapping the Flow of Forest Migration through the City under Climate Change

“…The cli- Table 1. Key parameters about the dispersal ability of Eurasian jays, obtained from Conway and Fuller (2010), Dyer (1995), Gómez (2003) and Rolando (1998).…”