Volume 15 Issue 1 Pages 1 - 67 (April 1998)

Citation: Soutullo, A., Garbera, R.P. and Gonzalez, E.M. (1998) A Preliminary Survey on the Status of Otters in Uruguay . IUCN Otter Spec. Group Bull. 15(1): 48 - 55

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A Preliminary Survey on the Status of Otters in Uruguay

Alvaro Soutullo¹, Ramiro Pereira Garbera¹ and Enrique M. Gonzalez²

¹VIDA SILVESTRE, Sociedad Uruguaya para la Conservacion de la Naturaleza. Colonia 1884/903, 11200 Montevideo, Uruguay. e-mail: vida-silvestre@geocities.com
²Museo Nacional de Historia Natural. Casilla de Correo 399, 11000, Montevideo, Uruguay

Received 27th April 1998, accepted 3rd July 1998

INTRODUCTION

The current distribution of the Neotropical river otter (Lontra longicaudis) includes all the Latin American countries from Mexico to Argentina, but excluding Chile. Its conservation status is, however, unknown in some of these countries (Chehébar, 1990; Parera, 1996).

Bocage (1992) reported Neotropical river otters as scarce in Uruguay, with healthy populations only remaining in the area of Bañados de Rocha (eastern part of the country). Chehébar (1990) considered the species widespread throughout the country, with main populations seeming to be in the area of Bañados del Este, Tacuarembo and Esteros de Farrapos.

The former distribution of the giant otter (Pteronura brasiliensis) probably included every country from Panama to Uruguay and northern Argentina (Parera, 1996) except Chile. The current distribution is fragmented, with recorded populations in Ecuador, Colombia, Brazil, Venezuela, Peru, Bolivia, Paraguay, Surinam, French Guyana and Guyana (Chehébar, 1990; Parera, 1996). If they have not been actually extirpated from Argentina and Uruguay, they are probably the most threatened mammals in these countries (Parera, 1996 and pers. obs.).

There are no previous surveys on the distribution and conservation status of Lutrines in Uruguay. The group is represented in national zoological collections by only 18 specimens of L. longicaudis and a single skull of P. brasiliensis collected in 1963.

The main objective of this survey was to establish the current distribution of otters in Uruguay.

MATERIALS AND METHODS

An otters sightings survey was carried out in Uruguay between September 1997 and March 1998. Forms for this survey were distributed by mail to more than 80 Uruguayan researchers, environmentalists and wildlife technicians. For Neotropical river otters the survey was restricted to sightings of otters or their tracks recorded within the last ten years. There was no restriction for records of giant otters.

For L. longicaudis, each form was to be filled with the information of a single sighting (only the most recent observation was recorded if otters or tracks had been observed in that locality on more than one occasion). Each form also requested information about the date of the sighting, the locality, the number of otters observed, how many times otters were observed there and the time of the day when the animals were seen. The following information was also requested for each locality. Considerations about the main threats to their conservation, characteristics of the stream where the observations were made (kind of stream, depth and width), characteristics of the river banks (abundance of plant cover and morphology), and observations on the behaviour of the animals (e.g. vocalisations).

The information about distribution was completed with records from material conserved in the Museo Nacional de Historia Natural de Montevideo (MNHN) and the Facultad de Ciencias zoological collections, and data from literature.

RESULTS

A total of 71 forms were returned. Fifty eight new localities for L. longicaudis and six new records for P. brasiliensis were added to those already known. These results have tripled the number of localities known to be inhabited by otters in Uruguay (see Table 1 and Figure 1).

Figure 1. Map of the main rivers and streams of Uruguay indicating places of otter records. (click for larger version)

Comments about behaviour, as well as data about the characteristics of the habitats used by Neotropical river otters were also obtained. In a preliminary analysis of the collected data, no preference for specific habitats was detected. All reported sightings were diurnal. Incidental capture of this species in “nutrias” (Myocastor coypus) traps were reported (J. A. Fernandez, and R. M. Spinola, pers. com.). Three road-kills were recorded.

DISCUSSION AND CONCLUSIONS

The survey data, the zoological records and the published data strongly suggest that Neotropical river otters occur throughout Uruguay. Within the last ten years Neotropical river otters have been observed at least in 17 of the 19 political divisions (“Departamentos”) of the country. There is no reason to assume that they have been extirpated from those where no recent records have been reported. No conclusions about the areas of the country that support the main populations of this species can be inferred from our survey.

The Neotropical river otter should be considered at least as a fairly common species in Uruguay. Despite this, their populations might be decreasing, and further research should be carried out to discern whether this suspicion has actual fundaments. The results of this research suggest that the former consideration of the species as scarce in the country (Bocage, 1992) was due to the lack of information and not because of actual conservational features.

Although some authors suggest that river otters are nocturnal and crepuscular animals in Uruguay (Gonzalez, 1983; Saralegui, 1996; Ibarra et. al., 1998), all the sightings reported in this survey were diurnal. We conclude from this data that in Uruguay these animals are, at least in part, also active during the day. Whether they are mostly diurnal or crepuscular and nocturnal in Uruguay is not clear yet. Parera (1996) reports this species as diurnal in Argentina, and considers that they become more nocturnal when they are disturbed.

The situation of the giant otter in Uruguay is uncertain. Although Redford and Eisenberg (1992) present four localities for this species in Uruguay, there is only one documented record (Ximenez et al., 1972). This paper presents two localities where they were observed in the late seventies, as well as a sighting of two individuals foraging in 1996. This would be the most southerly record for the species over the last 20 years. As the species is currently thought to be extirpated in Uruguay, and the latest record has to be confirmed, further observations are necessary to confirm the occurrence of the giant otter in Uruguay. Accurate surveys to assess the status of this species should be carried out immediately.

ACKNOWLEDGEMENTS - This survey was supported by VIDA SILVESTRE, Sociedad Uruguaya para la Conservacion de la Naturaleza. We thank the people that provided the information for this paper for their kind co-operation, and the assigned reviewer for their contributions to improve the manuscript.

REFERENCES

Bardier, G. (1992). Uso de recursos y caracteristicas del habitat del “Lobito de rio” Lutra longicaudis (Olfers ,1818) (Mammalia, Carnivora) en el Arroyo Sauce, SE de Uruguay. Boletin de la Sociedad Zoologica del Uruguay, (2ª epoca) 7, 59-60, Montevideo.
Bocage, A. (1992). Mamiferos del Uruguay. Servicio Divulgacion Cientifica, Division Cultura, Intendencia Municipal de Montevideo, 112 p.
Chehébar, C. (1990). Action Plan for Latin American Otters (pp:64-73). In: Foster-Turley, P., Macdonald, S.M., Mason, C.F. (Eds.) Otters: an action plan for their conservation. I-IV+1-126 p. IUCN, Gland.
Gonzalez, J.C. (1983). Los mustelidos del Uruguay. Almanaque del Banco de Seguros del Estado (Montevideo), 66: 227-229.
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Parera, A. (1996). Las “Nutrias Verdaderas” de Argentina (2ª Ed.). Boletín Técnico. Fund. Vida Silvestre Argentina (Buenos Aires). 21: 1-38,.
Redford, K. H., Eisenberg, J.F. (1992). Mammals of the Neotropics. The southern Cone. Vol. 2. Chile, Argentina, Uruguay, Paraguay. The University of Chicago Press, 430 p.
Saralegui, A. (1996). Lobito de Rio Lontra longicaudis (Olfers, 1818). Parques Municipales de Montevideo, Serie Fauna Silvestre del Parque Lecocq. Departamento de Cultura, Intendencia Municipal de Montevideo y Vida Silvestre, Sociedad Uruguaya para la Conservacion de la Naturaleza 3: 1-4.
Ximenez, A., A. Langguth, and R. Praderi. (1972). Lista sistematica de los mamiferos del Uruguay. Anales del Museo de Historia Natural de Montevideo, 7: 1-49.

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