According to Holechek (1982), the microhistological analysis gives satisfactory results. However, one weakness is the differential fragmentation and digestion between plant species which influences the frequencies of occurrence. Thus, it is possible to observe an overestimation of grasses (McInnis et al. 1983). This was one of the reasons that stomach analysis was preferred over fecal analysis, as it is considered a more accurate method of determining the diet of herbivores, although Homolka (1986) did not find significant differences. However, if hares consume a considerable amount of seed and fruits, then diet is better studied using stomach contents (Green et al. 2013).
In many stomachs, a considerable amount of large food pieces by fruits and seeds were observed. Separating and dry weighting fruit and seed content permitted a more accurate estimation of their consumption. This may explain the reason why a higher percentage of fruit and seed in diet of hare in the dry season was found compared to other studies in Mediterranean (Sfougaris et al. 2006; Paupério and Alves 2008; Kontsiotis et al. 2011).
Diet analysis revealed that hares in the study area consume mainly wild plant species (except cereals and grapes). Many studies have revealed that hares that feed in farmlands prefer wild herbs over cultivated plants (Brüll 1976; Frylestam 1986; Reichlin et al. 2006). The mosaic landscape permits hares to access many wild plant species, so any impact to agricultural production is limited at this period. Moreover, farming contributes to the enrichment of a hare’s diet with plants such as C. arvensis and Amaranthus spp. These plant species can be found growing within the irrigated crops such as watermelon. Grapes from the vineyards were also consumed. In one pregnant adult female’s stomach, large pieces of grapes (6 g dry weight) were found, and these comprised 20.7% of the total dry weight of the stomach content.
The number of identified plant taxa per stomach was 6.8 and was higher than in a study in Denmark where the mean number of plant taxa found in each stomach was 3 (Hansen 1996). This information is not provided by other authors. Although we examined a smaller number of hare stomachs in comparison with other studies in more northern European farmlands (Frylestam 1986; Hansen 1996; Reichlin et al. 2006; Katona et al. 2010), we found a higher number of plant species eaten by hares. In comparison with studies carried out in the Mediterranean, we found more plant taxa than Karmiris and Nastis (2010) in their small shrubland study area (300 ha). On the contrary, Sfougaris et al. (2006) and Kontsiotis et al. (2011) found a remarkably higher number of identified plant taxa when examining the autumn and winter diet of 318 and 217 hares, respectively. However, these hares were collected from broad geographical, mainly upland, study areas of thousands of km2. The larger number of plant taxa they recorded is probably caused by the larger number of hares examined and the larger study areas, as the standardized Levins’ niche dietary breadth index (BA) calculated by Kontsiotis et al. (2011) was lower than that of this study. The Shannon-Wiener function (H΄) calculated in this study was approximately two times higher than that of studies conducted in continental climates (Puig et al. 2007; Katona et al. 2010), whereas it was similar with that of other studies conducted in the Mediterranean (Karmiris and Nastis 2010; Kontsiotis et al. 2011).
Grasses (Poaceae) constituted the bulk of the diet, and similar results were found in continental Europe (e.g., Katona et al. 2010) and mountainous and shrubland areas in the Mediterranean. In our farmland study area, grasses (leaves and stems) accounted for 40.24% of the diet and seeds of grasses accounted for 5.37%. Sfougaris et al. (2006) refer a total percentage of 36% of grasses in examined stomachs. Kontsiotis et al. (2011) refer that in examined stomachs, leaves and stems accounted for 24% of the diet and seeds accounted for 2.1%. In two studies where feces were examined (Paupério and Alves 2008; Karmiris and Nastis 2010), a considerably higher total percentage of grasses was found, about 65%.
In this study, a higher percentage of grass seeds (5.37%) was found to be eaten during the dry period. This is probably due to the cereal stubble fields present in the study area and the applied method of separating large food pieces. Indeed, one hare stomach contained a huge piece of starch (16 g dry weight) by grass seeds that comprised 40.5% of the total dry weight of the stomach content. A high percentage of grass seeds (9%) was also found in stomachs examined by Katona et al. (2010).
Hares adapt their diet according to vegetation in each season. ANOSIM analysis indicated that the diet composition between the two seasons differs significantly, and SIMPER analysis showed that seeds, fruits, C. arvensis, and Amaranthus spp. consumed in the dry season were replaced by winter grasses and Medicago spp. in the wet season. Higher consumption of grasses in winter has been found in continental Europe (e.g., Reichlin et al. 2006), whereas in year-round studies in Mediterranean mountainous and shrubland areas, the consumption of grasses was also found to increase slightly in winter (Paupério and Alves 2008; Karmiris and Nastis 2010).
Foraging theory refers an expansion of diet breadth (Pianka 2000) and an increase in food consumption (Sinclair et al. 1982; Rogers and Sinclair 1997) when the availability of nutritious food decreases. Similarly, diet breadth may be dependent on the distribution of preferred plant species in space. When few preferred plant species are available in sufficient quantity and distributed evenly in space, herbivores do not need to search and to consume more plant species (Stephens and Krebs 1986; Shipley et al. 2009). In this study, an expansion of diet breadth in the dry season was found, mainly due to the consumption of seeds and fruits. Moreover, stomach content dry weight was higher in the dry than in the wet season, indicating an increase in food consumption. These two events are indications of the nutritional reduction of herbaceous plants at the end of the dry season. Indeed, most herbs are in a mature stage in the end of the dry season, something that decreases their forage quality. Simultaneously, fruits of woody plants ripen, and seeds of many grasses and cereals provide nutritious food.
Moreover, in our study area, hare food resources are patchier during the dry season than in the wet season where grasses, the main food source, grow abundantly throughout the study area after the rains. In the dry season, cereal fields, fruit trees, vineyards, and irrigated crops are all potential feeding grounds and each contains different plant species. It is assumed that each individual hare cannot visit all these feeding grounds in one night. Therefore, dietary niche breadth expands further in the dry season in comparison with the wet season but only when overall values are compared and not the mean values of individual hares (70.5% overall diet expansion vs. 20.6% diet expansion of mean individuals, according to BA in Table 1).
The expansion of diet breadth to include woody plants has previously been found for hare in colder climates, when the ground is covered by snow and herbaceous vegetation availability is decreased (Rödel et al. 2004; Green et al. 2013). We found evidence that a similar diet breadth expansion occurs in Mediterranean climates during the warm and dry seasons, but in this case, the limiting factor is the drought that decreases the foraging quality of herbs. Indeed, the improved diet of hares following the rainy season may be reflected in reproduction rates. Until the end of October, none of the females collected were pregnant, whereas at the end of autumn, after the rains, 50% of the collected females were pregnant and during the winter this number increased to 85%. A similar pattern was found in Crete by Antoniou et al. (2008).
Comparison of dietary parameters between age and sex classes is possible due to the relatively small study area considered, the similar landscape mosaic and vegetation across the study area, and the ability of hares to disperse more than 500 m each night to find their preferred food (Homolka 1985; Kuijper and Bakker 2008) and to cover a nocturnal distance ranging between 1.39 and 6.02 km within their home range (Pepin and Cargnelutti 1994). A higher diversity in diet H΄ and dietary breadth was found in juveniles than in adults in the dry season. Juveniles ate more dicotyledons than adults, and the adults ate more fruits and seeds. This indicates that juveniles cannot exploit all available food resources such as fruits and seeds. A reason may be is that fruits and seeds have more limited and patchy distributions. This is expected as juveniles have less knowledge of resource distribution (Gillingham and Bunnell 1989; Dahl 2005; Shipley et al. 2009) and, in some cases, are excluded by dominant hares (Lindlof 1978; Monaghan and Metcalfe 1985). The opposite seems to hold in the wet season when juveniles consume mainly nutritious and abundant winter grasses and have a narrower niche breadth than adults.
A second reason for fruit avoidance by juveniles may be because of the high concentration of secondary compounds contained in fruits (Jordano 2000). Iason and Waterman (1988) found that reproductively active females and leverets of Lepus timidus ate smaller proportions of heather Calluna vulgaris, than non-reproducing females and males, due to secondary compounds contained in this plant. However, in this study no differences were found between the sexes. Similarly, Homolka (1987) found no significant difference in diet composition between males and females.
Demeter and Matrai (1988) did not find differences in stomach content weights according to sex and age in Hungary, although Eley (1970) did find higher weights of female cape hares (Lepus capensis) than males. In this study, higher stomach content weights of adults and females were found, but they were not statistically significant. More female specimens collected in the wet season were pregnant and their higher energy requirements may force them to higher consumption (Hackländer et al. 2002).
The high plant diversity recorded in the area studied allows the examination of how specialist or generalist in diet the hare can be. Mammalian herbivores are classified as specialists if at least 60% of their diet consists of a single, distinctive plant genus or family (Shipley et al. 2009). In this study, the highest percentage of one single family was 49.52%, the Poaceae, during the winter. Therefore, the grasses, even when their availability and palatability is high, do not render the hare as a specialist. However, in other studies, the hare behaves as a specialist on grasses consuming more than 60% (Hansen 1996; Katona et al. 2010). According to (Shipley et al. 2009), the hare could be characterized as a facultative generalist as it is able to survive with a restricted diet breadth but prefers a broad dietary niche when the plant diversity is available.