Temperature and exudativory as drivers of the marmoset (Callithrix spp.) daily activity period.

Primates are affected by fluctuations in ambient temperatures, mostly through thermoregulatory costs and changes in the availability of food. In the present study, we investigate whether the ambient temperature and proxies of food availability affect the activity period of marmosets (Callithrix spp.). We predicted that: (i) at colder sites, marmosets would spend more time at sleeping sites; (ii) midday resting bouts would be longer at hotter sites; (iii) the onset/cessation of activity and resting behavior at midday would be more closely related to temperature than food availability, and (iv) highly exudativorous groups would have higher total levels of resting. We compiled data on the onset and cessation of activity and the time spent resting at midday from seven marmoset studies from sites with a wide range of temperatures. We used generalized linear mixed models to verify the relationship between the dependent variables (lag between dawn and the onset of activities, lag between cessation of activities and dusk, and proportion of resting during midday) and the minimum and maximum temperatures at the respective study sites, together with proxies of food availability (exudativory rates, the amount of habitat available per individual, and net primary productivity) using each sample month as a sampling unit and the identity of the study as a categorical random factor. At colder sites and during colder months, the marmosets left sleeping trees later in the morning and ceased their activities earlier, while at hotter sites and during hotter months, they spent more time resting during midday. More exudativorous groups become active later in the morning, but also ceased their activities later. The abundance of food did not affect the timing of activities. We provide evidence that both low and high temperatures affect marmosets' activities, and that their activity period appears to be more influenced by the thermal environment than food availability.

The occurrence of the red-handed howler monkey (Alouatta belzebul) in amazonian savannas is related to forest patch area and density of flooded area palms.

All Neotropical primates are arboreal and thus depend on forests for their survival. Arboreality puts many Neotropical primates at risk of extinction due to the high rates of deforestation in the tropics. We assessed the influence of vegetation structure and forest patch attributes on the occurrence of the threatened red-handed howler monkey (Alouatta belzebul) in an Amazonian savanna. Using a sample of 38 forest patches in a region of approximately 2000 km2 in the state of Amapá, northern Brazil, we used logistic regression to find the best predictors of the occurrence of A. belzebul. We assessed patch area, patch isolation, the proportion of seasonally flooded forest in the patch, the density of flooded area palms, forest height, canopy cover, and diameter at breast height of trees. Patch area and palm density were the best predictors of the occurrence of A. belzebul in forest patches, both having a positive effect on the probability of occurrence. Our results indicate that areas of flooded forest in forest patches may be keystone habitats for A. belzebul living in Amazonian savannas. The observed effect of palm density on A. belzebul suggests that this variable is useful for planning conservation actions, including the selection of areas for protection and management strategies for areas inhabited by this primate.

Consumption of leaves by Platyrrhinus lineatus (Chiroptera, Stenodermatinae): are these bats primarily frugivorous or broadly phytophagous?

Until now, the consumption of leaves by bats has been considered rare or sporadic, even among the herbivorous families Pteropodidae and Phyllostomidae. Among the phyllostomids there are reports of folivory in the genera Artibeus and Platyrrhinus, based on opportunistic observations. Here, we conducted behavioural sampling using camera-trapping in the roost of a colony of Platyrrhinus lineatus already known to consume leaves during the dry and wet seasons, in order to investigate the frequency of leaf consumption, as well as eventual seasonal differences. We observed feeding activity in 80.5% of sampling nights, where fruit was present in 90.3% and leaves at 80.6%, with no significant differences between the consumption of items. When analyzing video recordings, we observed feeding activity in 22.2% of the samples, in which the consumption of fruits was significantly more frequent than the consumption of leaves. We also observed seasonal variation, with the consumption of leaves being significantly higher than that of fruits during the dry season, whereas in the rainy season, fruits were consumed significantly more frequently. Fruits and leaves were consumed in equal proportions during the night, with no differences between the early and late night. Our findings show that the consumption of leaves by herbivorous bats may be more widespread than previously thought. Leaves may often be a regular food item rather than a fallback.