GIANT OTTER XIXUAU PROJECT
Biology and Ecology of Pteronura brasiliensis in the Xixuau Reserve

RESEARCH PROPOSAL 2001

The Giant otter (Pteronura brasiliensis) is the biggest among all the 13 otter species of the world and one of the greatest predators of the tropical rainforests of South America. It belongs to the Mustelidae family and inhabits fresh waters and lakes where it lives in family groups with a complex social structure. The Giant otter’s former range extended over Venezuela throughout northern Argentina in the northern half of South America and it dramatically declined between the 1950’s and the 1970’s due to the international pelt trade. Today Giant otter populations only survive in the last, most remote and undisturbed areas of the tropical rainforest and the IUCN Otter Specialist Group has classified it as endangered. Destruction of the proper habitat, deforestation and antropic pressure are the primary threats to the survival of the species considered an important bio-indicator. Only few data have been gathered until now concerning its status, its behaviour, the population structure and dynamics, as well as the threats it is facing. The scarce knowledge and its endangered status are the main factors which claim a new investigation and conservation project on this species.

The Reserva Ecologica do Xixuaù-Xiparinà is situated 500 km north of Manaus, along the Rio Jauaperì, tributary of the Rio Negro which marks the border between the Brazilian states of Amazonas and Roraima. The reserve is located approximately at 30m a.s.l. and measures 172.000 hectares. It consists of primary and secondary forest. On the northern sector it borders the indios land of Waimiri-Atroari, who prevent fishing boats from sailing the Rio Juaperi, contributing to its preservation. The Associação Amazônia established it in 1992 and since then has managed and pursued the protection of its wildlife. During the low water season, rock formations and sandy beaches emerge from the river and create natural barriers that increase the habitat diversity. Average annual temperature is of 25° C.
The area is virtually uninhabited, with a population density lower than 1 per sqKm. Approximately 30 people (more than a half under 10 years of age), divided into 6 family groups, live of fishing, agriculture and a little tourism due to the Associação Amazônia’s activities. In the same area a short term study has been promoted by the Inpa (Instituto Nacional de Pesquisa da Amazonia) of Manaus, in 1993. Considering that this species are the first to abandon degraded areas, its strong presence in the reserve is a sign that the area is still to be considered as unalterated by antropic pressure (Rosas, 1993).

The main focus of the project is to provide informations on Giant otter’s ecology and behaviour that can be useful to its conservation and management. The following aspects will be studied:

Side objectives
Interspecific observations within the ecological community:

Materials and methods
A one-year fieldwork is planned to gather the whole year round informations on movement patterns, habitat use and diet.
- Direct observations
The animals will be observed through 8x40 binoculars and their position recorded by a Gps 12Etrex Garmin. Each individual will be identified by the neck specific pattern and it will be filmed with a Camcorder in order to produce an ID card. Data on sex, age class, the role within the group, the activity pattern and on the behaviour will be gathered, drawings will be traced and for each observation date, time, coordinate and climatic conditions will be recorded.
Observations from hides will be done in the proximity of the dens at dawn and sunset, a daily monitoring of the river banks will be conducted in order to record all the different activities of the studied groups of Otters. Both solitary individuals and groups will be followed from a distance of 30m to 100m by a 4m long wood canoe. A data base will be generated and all the data collected will be transferred on a map using a GIS (Geographical Information System).
- Indirect observations
An intense monitoring along the rivers banks and lakes will be conducted searching for signs of Giant otter’s presence. Each campsite, communal latrine and den will be localized on a map and their ecological role will be described. In order to identify the alimentary habits faecal samples will be collected from the communal latrines through the whole study period, the spraints contents will be analyzed by the research team of Aquatic Mammals Department of Inpa (Instituto Nacional de Pesquisa da Amazonia), coordinated by Fernando Rosas. Nocturnal surveys will be conducted in order to verify the presence of the Black caiman, considered as a potential Giant otter predator (Brecht-Munn & Munn, 1998).

Study period
From February 2nd to 14th 2000, a preliminary survey of the area has been conducted, followed by a longer period, from October 20th 2000 to February 24th 2001, to identify the characteristics of the area.
Of 114 days spent in the study area, 65 days have been dedicated actively to search the family groups along the rivers, for a total of 441 hours. 26 days were used for a wider investigation on the habitat and on the rain forest ecosystem. Within the study period, 6 family groups have been located for a total of 27 individuals, for 13 of which the neck pattern has been described.

From October 20th to December 6th 2000 a little area in the reserve and a wider area along the Rio Jauaperi extending north up to Xiparinà, south up to Samauma and east up to Lake Tucurà, have been monitored. For each family group sighted coordinates, date, time and climatic conditions have been recorded. Furthermore, a data sheet has been compiled with individual’s drawings and informations on the habitat and on their behaviour. Within the whole study area location of dens, campsites, resting places have been recorded and when possible, faecal samples have been collected.

A single family group has been studied from December 19th to February 24th 2001. Information regarding time budgeting, behavioral, reproductive and alimentary habits was collected. The group, named Mpair (1:1:1) consisted of a reproductive couple and one cub born during the study period. Mpair, gradually used to the researcher presence, consented continuous observations of the behavioral activity both in the water and on the river bank, for a total of 23 hours and 27 minutes. The cub has been observed within the first 5 weeks of life, in 10 occasions for a total of 1 hour and 5 minutes.

A further study period of 12 months is scheduled starting from October 2001 to gather information’s on habitat and resources utilization in the different seasons of the year.

e-mail frosas@inpa.gov.br

tel +39 6 55176328
(Giuseppe M. Carpaneto)
e-mail carpanet@uniroma3.it

Thanks to Canon Italia (www.canon.it), to Fondo per la Terra Onlus (www.fondoperlaterra.org) and to Guardie Ecologiche Volontarie di Modena (www.geocities.com/RainForest/Vines/1644) for the generous support.

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