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The main goal of this study was to investigate the spatial use and the habitat selection of 24 sub-adult fallow deer males. The research took place in the San Rossore Estate (Pisa), a 4650 ha area characterised by a sub-Mediterranean climate.
The fallow deer population in the Estate adopts a mixed mating system, as males may adopt both territorial and non territorial strategies. The male strategy characterized by the higher reproductive success is the defence of a territory inside one of two traditional reproductive arenas (lek) in the Estate. The animals chosen for research was captured, fitted with radio-collars, and monitored using radio-tracking techniques. The localization (fix) of each male was carried out by two operators using the triangulation technique. More in particular, from December 2004 to March 2006, at least 10 localizations were collected monthly for each animal. Data collection was increased during the autumnal rutting period (one fix every twelve hours) in order to better know deer movements during this crucial phase of the annual biological cycle.
Localizations collected during the research were processed using the software Ranges VI in order to establish the size of annual and bimonthly home ranges, using both the MPC and the Kernel methods. This software was also used to determine home range overlaps and distances among centres of activity. The data about use of the space were analysed by non parametric statistic. Habitat selection of sub-adult males was studied using the compositional analysis of habitat. In particular, a special Excel macro was used in order to obtain a ranked sequence of vegetation typologies from most to least selected. Data regarding sub-adult male habitat selection were analysed using MANOVA. This study has underlined modifications in spatial behaviour which sub-adult males were subjected during the transition from the age classes of prickets (1-2 years) to sores (2-4 years) ones. In particular, during this period sub-adult males gradually leave female groups to join males ones.
Consequently, sub-adult males showed significant variation both in the use of the space and habitat selection, as they gradually occupied smaller home ranges but richer in grazing areas availability. This is a characteristic that distinguishes adult males from adult females, as the latter usually occupy bigger home ranges but localized in poorer areas of the Estate. Furthermore, sub-adult males showed low fidelity to areas occupied during the year with respect to those recorded for adult
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males. This high mobility is the evidence of lower knowledge of trophic resource distribution, which is commonly associated to young age classes of many ungulate species. The intensive data collection performed during the rutting period allowed us to subdivide the sample in males that attend lek and males that doesn’t reach this reproductive arena. The radiotracking data collection, according to direct observations performed in October inside the lek, has permitted to underline that sub- adult males attending lek, neither succeed in active defending territory nor in approaching fertile females. The only reproductive strategy which can be adopted by monitored sub-adult males is the non-territorial one, i.e. the following of females during their daily movements at dawn and dusk. The presence of adult territorial males in the lek doesn’t permit young males to have access to females in lek territories, that are the areas where most of females were fertilized every years, as it was showed in the previous researches which took place in San Rossore Estate.
