TUBERIAS Y ACCESORIOS EN POLIETILENO DE ALTA DENSIDAD (PEAD)

In this thesis I will focus on another important aspect related to habitat degradation and fragmentation, that is, the landscape of fear surrounding the lemurs. Indeed we expect a higher perceived predation risk among the groups living in the degraded area compared with lemurs living in the more preserved one.

More in detail, I will test the following research hypotheses:

ECOLOGICAL CORRELATES TO PERCEIVED PREDATION RISK IN LEMURS:

1. Are there any differences between the degraded forest (Mandena) and the more intact one (Ste Luce) in terms of animals' perceived predation risk?

according to a higher edge effect in the more fragmented forest, I would expect that lemurs living in Mandena should be more exposed, thus they should perceive a higher predation risk, measured in terms of frequency of anti- predatory behaviours.

2. Are there any differences between the lemur groups studied in terms of perceived predation risk, due for example to their different home ranges and group size?

According to the theory of dilution effect, and to the possibility of sharing vigilance tasks, I would expect a lower perceived predation risk in larger groups rather than in small groups.

3. Does the animals' use of the tree crown influence their perceived predation risk?

Since the main predators of Eulemur collaris in the two study areas are aerial predators [Donati, pers. comm.], I would expect that the animals perceive a higher predation risk when they are at the extremities of the crown.

4. Does the animals' use of the canopy influence their perceived predation risk?

Assuming that aerial predator attacks are most likely to happen in the upper part of the canopy, where the lemurs are more exposed, I would expect a higher perceived predation risk when they are in the upper forest layer.

5. Does the presence of other individuals sharing the same feeding or resting patch (party size) influence the frequency of anti-predator behaviours?

I would expect that the distance at which the animals are able to detect predators to increase with the size of their party, as it has been observed in other studies.

6. Are there any differences in terms of perceived predation risk caused by seasonal variations (as a consequence of food resource fluctuation) in the lemurs' daily distance travelled?

Assuming that the animals moving further tend to be more conspicuous (because of the higher patch depletion rate), I would expect them to be more vigilant and thus to spend more time scanning the environment than those moving less.

7. Since habitat differences have been related to difference in physiological stress in these lemurs [Balestri et al., 2014], is there any correlation between animals' landscape of fear and their physiological stress?

I would assume that more stressed animals should perform less frequent anti- predator behaviours being in a state of either potential nutritional deficit (the more likely cause of stress in these forests) or reproductive effort and thus less able to cope with other survival behaviours.

Since it was proposed that animals' spatial range use is mainly influenced by the distribution of resources and the presence of predators [Willems and Hill, 2009], all the above hypotheses will be tested both during feeding and during

resting.

Whereas the effect of resource distribution is essentially a direct effect of local availability, the influence of predators is mainly indirect: this means that, while the distribution and availability of resources are informative predictors of a species’ spatial ecology, predator distribution and density per se are not. Nevertheless, it was suggested that animals adjust their habitat use to their perceived predation risk [Lima and Dill, 1990; Willems and Hill, 2009].

In light of these considerations, I predict a difference in terms of resource priority and lemurs' perceived predation risk between the time spent feeding and the time spent resting. More in detail, I expect that each ecological correlate to perceived predation risk in the animals may influence anti-predator behaviours in a different way depending on whether lemurs are feeding or they

are resting. In fact, whereas the lemurs can actively choose the areas where to rest, the spots chosen for feeding are instead an obligate choice due to the scattered distribution and the highly variable availability of food resources. Thus, I expect the animals to be more vigilant and to perform more alarms while they are feeding.

SOCIAL CORRELATES TO PERCEIVED PREDATION RISK IN LEMURS:

1. In order to elucidate the possible advantage of the multimale-multifemale social structure in terms of vigilance efficiency, I will test if there are any differences in terms of frequency of anti-predator behaviours between sexes, and/or between low-ranked and high-ranked individuals.

Since it was proposed a possible anti-predator role of subordinate individuals, especially in the case of the extra-males which are observed in this brown lemur species, I would therefore expect a higher frequency of anti-predator behaviours and vigilance by males rather than by females, and/or by low-ranked individuals rather than by high-ranked ones.

2. Finally, I will test if there are any differences in terms of frequency of anti- predator behaviours between the season in which infants are present and that one in which they are not.

I predict a higher frequency of alarms and vigilance in the presence of offspring, that should be most vulnerable to predator attacks.

Answering all these questions may give a further insight into the eco-ethological responses and adaptations put in place by a medium-sized and flexible lemur species in order to cope with habitat fragmentation and degradation. This aims at providing additional conservation guidelines to preserve a species that is crucial to the littoral forest restoration, due to its fundamental ecological role for seed dispersal. Being the largest lemur species in the area, this animal represents a so-called “umbrella” species, that means that by protecting

Hence, understanding the relationship between perceived predation risk and forest fragmentation is important in terms of ecology and conservation management.

Fig. 8 The humid littoral forest of South-East Madagascar. Mandena, Fort Dauphin. Photo by Marta Barresi, May 2011