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San Sebastian II

18/12/2015, 17:46

29-30 November 2015

Today the main focus of the day was to record the bird (especially raptors) activity. Therefore we used the vantage point method. We observed birds from the water tower at the main building in the morning from 7-10 AM and in the afternoon from 4-6 PM. We build 3 groups each two person who was responsible to observe one hour in the morning and one hour in the afternoon. We wrote down the time, species, direction (N-E-S-W) and behavior. We could report a lot of vultures, but also the roadside hawk (Buteo (rupornis) leucorrhous), plumpeous kite (Ictinia plumbea) and the hook-billed kite (Chondrohierax uncinatus) could be observed.

Photo: (c) Martin Jansen
Photo: (c) Martin Jansen

In the afternoon we made an experiment with the seven frogs (Pseudopaludicola mystacalis) we caught in the night before. We kept the frogs individually with three different surfaces (mud, green leaves and white paper) for 1.5 hours to see if they change their skin texture depending on the underground. Afterwards we took a picture of each individual under the same conditions to measure possible differences. Then we changed the surface for each individual until every individual was sitting on each surface for the specified time. Unfortunately, we couldn´t observe any differences. We cannot answer if they are actually no differences or if the experiment should be repeated for a longer time scale.

Photo: (c) Martin Jansen
Photo: (c) Martin Jansen

Photo: (c) Manuela Merling de Chapa
Photo: (c) Manuela Merling de Chapa

Afterwards we went looking for the dart frog (Ameerega picta). Unfortunately, they were not active and therefore we couldn’t find them. To observe the beautiful area around the field station we went horse riding again. This time we went to the crocodile lake, what was easier on horse.

In the morning the girls made a little walk. This time, we could observe the caiman during the day for the first time. He was resting on a little sand branch in a little water pond.

Oliver and Martin went to the tower from 6 – 8 AM to observe raptors again. But also during the day they were always showing up at the tower. Their focus was to see the king vulture (Sarcoramphus papa). To make it easier, we opened a “vulture restaurant” on our first day of arrival. Therefore, we placed cow heads to attract vultures. Luckily four king vultures and around 20 black vultures (Coragyps atratus) were visiting our restaurant.

Because the dart frog excursion of the day before was disappointing we gave it a second try. In the afternoon, we went to find them again and this time they were active and due to their calling we could find them. To test for the so called “Neighbor-Stranger-Discrimination” we started an experiment. We recorded the calling of different individuals for 2-3 minutes and played it in front of faraway neighbors. We were expecting that the territorial frog would attack the possible concurrent (the “stranger” played from recorder). Unfortunately, also this experiment didn´t work as expected. The frogs were curious about the recorder and answering but not attacking the recorder.

Photo: (c) Manuela Merling de Chapa
Photo: (c) Manuela Merling de Chapa

With this experiment our nice stay at San Sebastian ended. In the next morning, we went back to Santa Cruz. Goodbye Bolivia and thank you for the great opportunity to stay at the research station in San Sebastian!



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