Study of the marking behaviour of the largest Neotropical felids using non-invasive techniques
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AuthorshipGonzález Borrajo, Noa
Técnicas de investigación
Fecha de lectura2017-06-09
Large carnivores are important for biodiversity conservation, constituting an essential component in maintaining integrity and stability of ecosystems. In consequence, carnivores¿ conservation and the development of suitable management plans for them are crucial for the maintenance of whole ecosystems. These plans, to be successful, need complete information about species, which includes the study of their behaviour. However, the study of large carnivores is widely known for being very complicated, mainly because of their evasive behaviour and large home ranges, remaining most of them hardly studied, and many of aspects of their ecology and behaviour being still insufficiently unexplored. This study focuses on jaguars (Panthera onca) and pumas (Puma concolor), the largest felids of the Neotropics. Both are considered umbrella species, as they cover all the ecological requirements of a community; and key species because of their direct and indirect influences over the different ani ...
Large carnivores are important for biodiversity conservation, constituting an essential component in maintaining integrity and stability of ecosystems. In consequence, carnivores¿ conservation and the development of suitable management plans for them are crucial for the maintenance of whole ecosystems. These plans, to be successful, need complete information about species, which includes the study of their behaviour. However, the study of large carnivores is widely known for being very complicated, mainly because of their evasive behaviour and large home ranges, remaining most of them hardly studied, and many of aspects of their ecology and behaviour being still insufficiently unexplored. This study focuses on jaguars (Panthera onca) and pumas (Puma concolor), the largest felids of the Neotropics. Both are considered umbrella species, as they cover all the ecological requirements of a community; and key species because of their direct and indirect influences over the different animals and vegetation species, maintaining the stability of ecological communities. They are also considered as flagship species, as they are easy attractors of environmental campaigns. Neither of this species is classified as threatened globally by the IUCN; however, they are not exempt from human pressures derived from population growth, for example, which triggers habitat fragmentation and loss or hunting pressure, with devastating effects on biodiversity. The general decrease of jaguar and puma population requires a search for alternatives to conflicts where they are involved. The understanding of the ecological needs of both species and their interaction with the ecosystem will result in the improvement of their own conservation status, but also of the rest of species within the community. A good option for the study of these elusive species is non-invasive methods, which usually allow the survey of most part of the population, being a suitable method for the investigation of carnivores¿ ecology, behaviour and population status. Specifically scats are easy surveyed and they present a lot of ecological and territorial uses for individuals, making their collection and analysis a powerful tool for the study of large carnivores¿ ecology. Furthermore, the importance of scats-based studies has greatly increased with the advances in genetic techniques, allowing researchers to identify species, sex and individuals from DNA extracted from them. This thesis is specifically centred in the study of the marking behaviour of jaguars and pumas in different areas of the Neotropics. With the study of the scat-marking patterns we aim to improve the knowledge about the behavioural ecology of these large carnivores. First, and to be able to interpret correctly the results of the scat spatial analysis, it is necessary to know the spatial behaviour of the species. Until these days, few studies have analysed the spatial behaviour of pumas and jaguars. Besides, existing studies are heterogeneously distributed along the geographical range of the species, with large areas remaining unstudied. Some aspects of the spatial ecology of the species are also unknown (e.g. there is hardly any information about the daily movements and dispersal behaviours of jaguars) and the methodology is highly different among studies, both in the field and in the posterior analyses. Consequently, and to deal correctly with the scats' spatial distribution analysis, in the first chapter we reviewed all the available studies about the spatial ecology of jaguars, pumas and ocelots to try to clarify and summarize all the information available about the different aspects of their spatial ecology. Here, we decided to also include the ocelot, the third largest felid of the Neotropics, as we considered important to have as much available information as we could about the largest felids of the Neotropics. This review showed that pumas presented on average larger home ranges than jaguars and ocelots. Three variables, sex, Ecoregion and latitude influenced the home range size of all three species; whereas only sex and latitude showed significant influence in the daily net displacement of ocelots. Results regarding territoriality showed that intersexual range overlap was higher than intrasexual in jaguars and pumas. Previously to analyzing the scats spatial distribution, it is necessary to take into account different variables which could affect the scats surveying and produce misleading results. In chapter 2, we analysed how different climatic and vegetation variables affect the scat detection rate in different areas of the Neotropics. Although biases and interpretational errors have been detected for laboratory and data analyses when using scats for ecological studies, biases related to scats sampling have rarely been discussed. The time that a scat remains recognizable in the field is almost unknown, and it can be an important source of error in many studies. In fact, our study showed that total precipitation and mean temperature of the three months preceding the survey negatively influenced scat detection rate; nevertheless, neither detection method, nor vegetation density and height, nor biome did show any significant effect. Studies based on the scat detection rate of jaguars and pumas may be biased by the influence of some of the mentioned factors affecting scat persistence. Investigators should minimize the biases induced by these variables taking into account, specially, precipitation levels and temperature of the areas surveyed. Once we studied the variables influencing scat detection rate in our surveyed areas, in chapter 3 we proceeded to explore the scats' spatial distribution pattern. It is known that scats are usually deposited over prominent and conspicuous sites or at strategic points on trails near the central area; especially at nearby junctions, points which are frequently remarked. These signals are used for leaving long term messages, such as territory marking and maintenance, individual recognition or signaling feeding places or sites with valuable resources. Here, we examined several aspects of jaguars and pumas spatio-temporal marking behaviour based on scats. Specifically, we examined the frequency of remarking at small and medium spatial and temporal scales, analyzing if scats were randomly deposited along their territory and evaluating if deposition points were mainteined over time. We observed that both species showed a remarking behaviour at specific places, confirming the use of scats as markign signals; however, jaguars remarked with a higher frequency and deposited the scats in a more aggregated way than pumas. This would suggest the dominant role of jaguars versus the subordinate species, pumas, which would try to avoid encounters with jaguars. Finally, in chapter 4, an to complement the knowledge available about the marking behaviour, we used scrapes data, as this is a known signal of communication among individuals. A couple of studies exist about the scrape-marking behaviour of jaguars and pumas, although these studies are mainly focused on generalities and they do not delve into specific aspects of this behavioural trait. This is partly understandable given that the interpretation of scrapping behaviour present some difficulties, one of them being the identification of the particular species that made the scraps. Only in the cases that there are fresh scats or urine over it, the owner of the mark can be identified and thus, the specific scrape can be assigned to a single species. Our results showed that most of the scrapes were found in car tracks, and they were usually located in the edge of the track; specifically, felids make scrapes on sites mainly covered by leaves and located along narrow paths, clean and rarely used. When comparing between areas, scrapes were located mainly in the centre of the path in areas only with pumas, in the centre and in the edge in areas with a similar number of jaguars and pumas, and in the edge in area mainly dominated by jaguars. This could indicate the existence of different scrape marking behaviours in the two studied species, although further studies are needed to confirm these findings. In conclusion, there is still much work to be done in order to obtain a detailed knowledge about jaguars and pumas marking behaviour, and about the use of the space to deposit scats and scrapes for intra and interspecific communication. However, the presented analyses of the marking behaviour (scats and scrapes) of the largest felids of the Neotropics is a first step towards the full comprehension of the spatial ecology of these two species facing increasing human pressures, and highlight the importance of their interacting patterns.
Programa de Doctorado en Estudios Medioambientales
- Tesis Doctorales