The adoption of landmarks for territorial boundaries

Helpers influence on territory use and maintenance in Alpine marmot groups

“…In particular, males scent-marked more frequently than females, and adult males scent-marked more frequently than yearling males. The function of scent marking might serve as intra-sexual competition inside the group (Jordan et al 2011) and/or territoriality between groups (Heap et al 2012). In according to previous work (Lenti Boero 1995) we found that Alpine marmots scent-marked mostly at the boundaries of the territory and that, in addition, the number of scent marking behaviour increased with the proportion of overlap areas among groups (Fig.…”

“…For example helpers can enhance their own future fitness by inheriting part or the whole territory that belongs to the dominant pair or by dispersing to neighbouring territories as soon as these territories become vacant (Cockburn 1998). 3 Benefits for the dominant pair may include active cooperation of the helpers in territory defence during intergroup aggression and their participation in the maintenance of territory boundaries using marking behaviours (reviewed by Heap et al 2012). Scent marking behaviours -i.e.…”

The role of landmarks in territory maintenance by the black saddlebags dragonfly, Tramea lacerata

“…They differentiate between two types of landmarks, constraining ones that physically restrict the visibility or movement of an organism, and non-constraining ones that serve only as conspicuous indicators of where a territory ends. Heap et al (2012) also describe two hypotheses that can explain how landmarks reduce the cost of defending territories. The first is the clear boundaries hypothesis.…”

“…The system should not work if an individual is unable to gain a sufficiently large territory. As Heap et al (2012) describe, the individual must also respond to the landmark. A landmark that is adopted as a convention may be constraining, it may exploit an existing sensory bias, or it must be used as a spatial reference (Heap et al 2012).…”

“…Landmarks reduce defensive costs and allow more individuals to establish territories in an area than would be possible without landmarks (LaManna and Eason 2003). Heap et al (2012) thoroughly review all studies that document the use of landmarks as territory boundaries. They provide evidence indicating that boundaries with landmarks persist longer than those without landmarks.…”