Seasonal trends and population status of the highly threatened Pteropus livingstonii in the Comoros archipelago.

Flying foxes of the genus Pteropus, especially those inhabiting islands, face increasing pressure from anthropogenic threats. A first step to implementing effective conservation actions is to establish monitoring projects to understand a species' population status and trend. Pteropus species are highly affected by seasonality which further requires regular, repeated, and long-term data to understand population trends, and reactions to severe weather events. In the present case study, a regular, bi-annual population census was implemented on Comoros between 2016 and 2023 for the highly threatened Livingstone's fruit bat, Pteropus livingstonii, and compared the results of standardized monitoring to historical population data. Seasonality had a large impact on the number of bats found at roost sites, with more bats present in the wet season, but the data over the past eight years revealed no significant in- or decrease in the number of bats counted on the island Anjouan. We estimated around 1,200-1,500 bats on Anjouan and 300-400 bats on Mohéli, and found that landcover type has no measurable effect on population distribution at roost sites. Our study highlights the need for long-term surveys to understand past population trends and that single counts are not sufficient to draw final conclusions of a species' status.

Sahamalaza Sportive Lemur, Lepilemur sahamalaza, Vocal Communication: Call Use, Context and Gradation.

Stereotypical vocalisations can facilitate long-distance communication in dense and, thus, sound-degrading forest habitats. Despite this, primate vocal repertoires often also include gradations between different call types that are used in social interactions. Because many nocturnal primates show a solitary social structure, it has been difficult to assess the role vocalisations play in mediating their social encounters. Here we aim to expand on the call types of Sahamalaza sportive lemurs, Lepilemur sahamalaza, as well as investigate their variability and use in social contexts. Through long-term behavioural observations with concurrent recording of vocalisations of known and unknown individuals between 2015 and 2016, we described three previously unrecorded calls and expanded the vocal repertoire to 12 different call types that were used in both targeted social and broadcast solitary contexts. Linear discriminant function and cluster analysis supported initial observations that vocalisations within call types were variable and that at least two call types can be classified as "graded," contrary to expectations. Despite variations in call-context connections, no clear patterns of call use could be established. However, measurable differences in vocal behaviour between the seasons and the sexes indicate that calling is used in a reproductive context, similar to other nocturnal and diurnal primates.

Spatiotemporal distribution of individuals as an indicator for the social system of Lepilemur sahamalaza.

Primate social systems are highly diverse, complicating the classification of particularly elusive species that are difficult to observe. The spatial distribution of individuals over time is a critica lindicator for the social organization and long-term studies are important to establish patterns of social interactions. In recent years, species of the cryptic, nocturnal sportive lemurs of the genus Lepilemur were found to live in pairs in which a single male and a single female share and defend a mutual home range. The present study aimed to forward research into this underrepresented genus by determining the social organization and structure of the Sahamalaza sportive lemur, L. sahamalaza. We collected 773.15 hr of behavioral and GPS data during a period of 10 months (between 2015 and 2016) on 14 individuals: eight females and six males. There was no evidence of pair-specific home range use as intra- and intersexual home range overlap was high. No pattern of social interactions between focal individuals could be distinguished despite high range overlap. Individuals met and interacted infrequently, resulting in an interaction rate of 0.32 interactions/hr. Sleeping associations between adult individuals were never observed. While both sexes had access to multiple potential mating partners, range sizes or ranging distances did not increase in mating periods. Overall, the social system of Sahamalaza sportive lemurs exhibits aspects of a solitary social organization and structure with potential for the polygamous mating system. These findings underline the importance of detailed social ecology studies that can provide the basis for understanding potential environmental influences on social system variability of closely related species.

The Effects of Climate Seasonality on Behavior and Sleeping Site Choice in Sahamalaza Sportive Lemurs, Lepilemur sahamalaza.

Temperature, rainfall, and resource availability may vary greatly within a single year in primate habitats. Many primate species show behavioral and physiological adaptations to this environmental seasonality, including changes to their diets and activity. Sahamalaza sportive lemurs (Lepilemur sahamalaza) inhabit the northwest of Madagascar and have been studied only during the dry, colder period of the year. We investigated potential effects of climate seasonality on this species by collecting behavioral data between October 2015 and August 2016, encompassing both the warmer wet and the colder dry seasons. We collected 773.15 hours of behavioral data on 14 individual sportive lemurs to investigate year-round activity budgets, ranging behavior, and sleeping site locations. Additionally we recorded temperature and rainfall data at our study site to describe the environmental conditions during the study period. The study individuals significantly decreased their time spent traveling and increased their time spent resting in the dry season compared to the wet season. Although home range size and path lengths did not differ over the study period, sleeping locations were significantly different between seasons as the lemurs focused on more confined areas in colder periods. Overall, the results indicate that Sahamalaza sportive lemur behavior varies with season, in line with reports for other primates.

Exploring novelty: a component trait of behavioural syndromes in a colonial fish.

Individual differences in exploratory behaviour have been shown to be consistent across contexts and suggested to be part of behavioural syndromes in a diversity of species, including fish. Exploration has also been shown to be a key factor in understanding complex ecological processes such as sexual selection and cooperation. Another important question in ecology is why animals breed in colonies. Exploration syndromes, by affecting prospecting behaviour, dispersal and public information use may also contribute to our understanding of coloniality. This study aims at investigating whether an exploration syndrome exists in a colonial fish species, Neolamprologus caudopunctatus. Individuals of this species were subjected to two consecutive tests, a novel environment and a novel object test. Results show that more explorative individuals in a novel environment are also less neophobic in the presence of a novel object, suggesting that the tendency to engage with novelty per se is a consistent trait and part of an exploration syndrome. These results are discussed in light of the contribution of an exploration syndrome to explain colony formation in animals.

Gaze following in the red-footed tortoise (Geochelone carbonaria).

Gaze following refers to the ability of an animal to orient its gaze direction to that of another organism. Such a behavior may be adaptive as it alerts the observer to important objects in the environment such as food or predators. This behavior has been shown in mammals and birds, but the evolutionary history and the distribution of this behavior throughout the animal kingdom remain unclear. Here, we show that a reptile, the red-footed tortoise (Geochelone carbonaria), is able to follow the gaze of a conspecific in a lookup task. Controls revealed that neither the mere presence of a conspecific nor the presentation of a light stimulus (without a demonstrator present) controlled the tortoises' behavior. The findings indicate that the ability to follow gaze may be found in mammals, birds and reptiles and could have evolved before the amniotic line diverged, or may result from a general ability to learn.