‘Territorial’ and ‘non-territorial’ males behaved similarly in the presence of females, but showed different behaviours in their absence (Table 5.3 and 5.7). For example, there was
a tendency among ‘territorial’ males to roar, mark, and show aggressive behaviour towards other males even when there were no females at stake. Often the differences between the two groups of stags were more evident in 1995, when the prolonged drought made forage scarce and body condition of animals was poor (see Chapter 4). This suggests that extreme environmental conditions may underline territorial behaviour in red deer in the Mediterranean. When stags fi'om Tapada were compared to stags from Rum, the ‘non-territorial’ males showed an intermediate behaviour between ‘territorial’ and harem holders (Table 5.7). Again, this was particularly true about rutting behaviour in the absence of females (Table 5.7). However, unlike harem holders (Clutton-Brock et al, 1982a) some of the Tapada ‘non-territorial’ stags were also observed roaring in the absence of females. This suggests that, instead of two distinct groups, Tapada’s males may be part of a continuum of mating strategies between pure territory defence and female defence. This would explain why some of the variables tested were not significantly different between the two groups, although larger sample sizes could, as well, made differences clearer. By dividing rutting males in two groups, predominantly ‘territorial’ or ‘non-territorial’, I was able to investigate the nature and the extent of differences in rutting behaviour between the two strategies. However, my Index o f Territoriality suggested that there is, in fact, a gradient of territoriality in Tapada, with only a few males showing strictly ‘territorial’ or “ non-territorial” behaviour (Fig. 5.2). Perhaps males that never mark in the absence of females are the only harem holders; males that mark the most are the true territory holders, and all the others adopt an intermediate behaviour. The two groups were rather homogeneous phenotypically (Table 5.2), but showed some significant differences in behaviour (Table 5.3). Due to all males being assorted to two separate groups, these significant results are conservative rather than chance alone.
Both ‘temtoriar and ‘non-territorial’ stags in Tapada roared at much higher rates (6-7 roars min'^) than those on Rum (2 roars min'^) (Table 5.6), though at rates similar to the ones recorded in Spain (Carranza, 1995). Moreover, in contrast to stags on Rum (Clutton-Brock and Albon, 1979), ‘territorial’ stags in Tapada were often observed roaring while lying down. Most ‘territorial’ males would arrive early in the day at the defended area, and they would settle down and start roaring on their own until the arrival of females. Some stags were observed roaring at a low (1-1.5 roar min'^) but continuous rate for over 12 hours (data for Stag 200 and Stag 265, based on five and four day-long focal watches, respectively). Considering the high energetic costs of roaring and the generally poor body condition of Tapada’s stags (see Chapter 4), it is rather surprising that roaring rates are so much higher in the Mediterranean than on Rum. This suggests that in the Mediterranean roaring probably plays a critical part in rutting behaviour. For example, it may serve primarily to advertise the continuous presence of a male in a certain part of the range, Klingel’s (1974) sound marking. The fact that roaring may advance oestrus could also explain the high investment in roaring in mediterranean stags (see McComb, 1987; 1991). The breeding season seems to last longer in the Mediterranean than in temperate climates (Arevalo, 1985; Soriguer et al, 1994; pers. observ ), which may be due to a lower synchronisation of oestrus in hinds.
The duration of the rut did not diflFer significantly between ‘territorial’ and ‘non territorial’ males, though there was a tendency for ‘territorial’ males to start rutting earlier and rut for longer (Table 5.2). Similar results were found by Carranza et al (1990) when comparing ‘territorial’ and ‘non-territorial’ red deer stags in Spain. These differences could be explained by the fact that, in addition to the increased amount of time spent interacting with females that is common to ‘non-territorial’ males, ‘territorial’
males need to invest extra time establishing their territories. Another possible explanation, is that stags will be exhausted quicker by female defence than by territory defence, since they must spend more time with females. Although not significant, there was indeed a trend in both years for the duration of the rut to be negatively correlated to the time spent herding females (see Table 5.1). Similarly, neither distance between sightings on consecutive days nor range size were significantly different between the two groups.
Another important feature of red deer mating behaviour in Tapada was the tenancy of a male’s exclusive access to a given female. ‘Territorial’ males held territories for a varying number of days (Fig. 5.6), but in any case did they hold females permanently within their territories. As described in Spain, when hinds leave a territory, the male lets them go without following them (Carranza et al, 1990). Walther (1972) described territoriality in a population of Thomson’s gazelle inhabiting an area of shrubland, where males defend small territories (an average of 200m in diameter) which are visited by roaming females during their daily circuit. Females were together with a given ‘territorial’ male for only a few hours per day. This seemed to be the case with ‘territorial’ males in Tapada, where territories were visited by ranging females for only a couple of hours during the late afternoon, as females followed a daily routine of moving between shrub cover and pasture feeding areas. In contrast, ‘non-territorial’ males in Tapada followed and herded females, but their task of maintaining a cohesive group was constantly hampered by the habitat mosaic, which made it difiScult to hold a harem when females moved into patches of scrub. Similarly, fallow deer bucks studied in Spain were reported to retain only temporary control over female groups, irrespective of whether they defended territories or held harems of females (Alvarez et at, 1990).
Because ‘territorial’ males did not follow females once they left their territories, and ‘non-territorial’ males probably found it difficult to keep together a party of females which moves across a patch of scrub, associations of Tapada’s stags with hinds were much looser than those on Rum (see Fig. 5.6). As a consequence, males in Tapada spent a considerably higher proportion of their time in the absence of females (half and 1/3 of their time, respectively) than stags on Rum (Table 5.7). As behaviour in the absence of females was precisely what distinguished ‘territorial’ fi'om ‘non-territorial’ males, this might explain the differences between harem-holders on Rum and ‘non-territorial’ stags in Tapada.