Financial support: INPA/MCT, Manaus Energia S.A., ReBio Uatumã and Fundação O Boticário de Proteção à Natureza.

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1 SOCIAL ORGANIZATION, BEHAVIOR AND DIET OF GIANT OTTERS (Pteronura brasiliensis) IN THE RESERVOIR OF BALBINA HYDROELECTRIC POWER STATION, AMAZONAS, BRAZIL. TEAM: Dr. Fernando Rosas (coordinator)/inpa. BSc. Gália Ely de Mattos/INPA. Dr. Jansen A.S. Zuanon/INPA. BSc. Monica R.B. Machado/INPA (MSc student). Vet. doctor Stella M. Lazzarini/CPPMA/UHE Balbina. Vet. doctor Márcia C.L. Picanço/CPPMA/UHE Balbina. Financial support: INPA/MCT, Manaus Energia S.A., ReBio Uatumã and Fundação O Boticário de Proteção à Natureza.

2 JUSTIFICATION Hydroelectric dams Isolate populations Change ichtyofauna Unknown giant otter s capacity to adapt to the new environment Nowadays, 15 years after closing the dam of Rio Uatumã, we recorded giant otters living in the lake. Is the hydroelectric lake used all year round? Is there reproduction in the hydroelectric lake? Is there any change in giant otters feeding habits?

3 OBJECTIVES General Objective To know the changes that have happened in the giant otters habits (social organization, den locations, feeding habits, reproduction) in order to evaluate the potential usage of hydroelectric reservoirs for the conservation of the species.

4 Specific Objectives -To identify and quantify the number of dens in use by giant otters in Balbina lake; -To identify the food habits of giant otters in the reservoir and to compare them with the data obtained from natural areas, without human interference; -To identify individuals by their natural marks, and characterize group compositions, territoriality, social organization and reproductive season in the reservoir; -To identify and to describe several giant otter s vocalizations, and to correlate the possible resonant functions with behavioral patterns of the species.

5 METHODOLOGY The Study Area The flooded area of Balbina hydroelectric reservoir covers a total of 911 square miles and has 2,300 islands (Fig. 1). Figure 1. Satellite image of Balbina lake.

6 Excursions monthly (first year) Methodology every other month (second year) camping from 5 to 6 days each time (Fig. 2) Figure 2. Camp site at Pitinga river, in Balbina lake.

7 Collecting feces samples for diet analysis Methodology Secchi disk Dens: GPS position; measuring their openings; classifying as in use vs. not in use (Fig. 3): Figure 3. Giant otter s dens in use. Balbina lake, Brazil.

8 Methodology Tool: branches to know if the animals are using the den at that specific timeframe. Figure 4. Branches in the entrance of the den. Balbina lake.

9 Visual contacts of giant otter groups (Fig. 5) Photo-Id Methodology Recording sounds Locating the den used by the group Play-back Figure 5. Group of 6 individuals. Balbina lake, Brazil.

10 RESULTS & DISCUSSION 51 groups identified 2-11 individuals per group Animals start morning activities from 05h20 06h29 (n=15) Returning to the dens from 15h10 17h38 (n=11) High den turnover rate Water level Presence of the researchers Predators (Fig. 6) Fig. 6. Jaguar in the study area.

11 The catalogue: Results & Discussion 115 giant otters identified in Balbina lake Figure 7. Catalogue of some giant otters identified in Balbina lake.

12 Results & Discussion Cubs observed in August, October, November and December Groups of 6 individuals are more confident behavioral and acoustic answer to play-back Fish in 100% of the feces analyzed 1.5% mammalian fur (monkeys and sloths)

13 Results & Discussion 1,50% 13,30% 0,74% 44,00% 16,30% 12,60% Cichlidae Erythrinidae Mammals (Primates & Xenarthra) Serrasalmidae Other Characiformes Siluriformes Figure 8. Numeric frequency of preys identified in giant otters feces from Balbina lake.

14 Results & Discussion consumption of piranhas Serrasalmus rhombeus Figure 9. Wound in right upper lip of giant otter.

15 Results & Discussion Giant otters were observed all year round in Balbina lake Regular reproduction The species seems to be very well adapted to the hydroelectric lake Hydroelectric lakes have potential for conservation of the species

16 That s it!