Faculty of Mathematics and Natural Sciences - Biogeography

Faculty of Mathematics and Natural Sciences | Geography Department | Biogeography | News | Collecting scats in the Gran Chaco - not an easy job!

Collecting scats in the Gran Chaco - not an easy job!

Our PhD student Asunción Semper-Pascual has recently carried out her fieldwork in the Argentinian Dry Chaco to collect data for one of her thesis chapters. Here you can find a report of her experience.

 

I have spent two months in the Argentinian Dry Chaco chasing collared peccaries with the aim to collect their fresh scats. Although it has been a great and unforgettable experience, I have to admit that it has been quite a challenge. But why is it that difficult to find peccaries´ scats? The first (and probably the main) reason is that such species are drastically disappearing in that region due to both the conversion of its habitat into cropland and pastures, and to poaching. Second, the Chaco is a dry forest which is very difficult to walk through since it is made up of dense and thorny vegetation, where walking 100 meters can take half an hour. Third, the high temperatures. Temperatures in spring can go up to 46 degrees Celsius and although walking in the field with such weather conditions is not easy, the main problem is that scats dry up very quickly.

Therefore, it has not been an easy job but I still came back to Berlin very satisfied with the number of samples that we collected. My success is mainly due to the help of my skilled field assistants and especially to the knowledge and experience of the locals. Most of them have lived in the field during their entire life and therefore they know exactly how animals behave and how to interpret their signs in the field. With their help, we managed to track peccaries in the forest and ended up in the places where they had defecated just a few hours earlier!

But why would anyone want to collect scats from peccaries? What kind of information can we get from scats? Scats provide a lot of information which can be used for several aims. For example to identify individuals (through DNA analysis), to learn about their diet or to estimate the distribution of a species. However, in this study we want to know something else. We want to know what the immediate effects of land-use changes are on peccaries. More specifically, we want to know about stress levels of individuals whose habitat have recently disappeared. After an individual is affected by an external stressor (e.g. loss of habitat), it responds by activating the hypothalamic-pituitary-adrenal axis which leads to a cascade of events ending in the secretion of glucocorticoids. Such glucocorticoids can be measured in scats. However, these glucocorticoids can only be accurately measured in fresh scats, which is why it is so important to find fresh scats for these types of studies.

Our partners from Argentina are currently analyzing the samples and we hope that our results can be integrated in future conservation planning. If species like the collared peccary are being affected by land-use changes at the individual level (e.g. a stressed individual reduces its reproduction capacity), the urgency would arise to protect this species and its habitat before the entire population is affected and local extinction occurs in the Argentinian Dry Chaco.

 

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Asunción Semper-Pascual and Dr. Julieta Decarre                 Dry forest of the Gran Chaco
(from INTA, Argentina) collecting scats in the field

 

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Dr. Julieta Decarre and Manuel (local) in the thorny dry        Asunción Semper-Pascual and Claudio (local) collecting forest                                                                               peccaries´ scats

 

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Asunción Semper-Pascual and José (local) collecting
peccaries´ scats