Large- and Medium-Sized Land Mammals of Northeast Marajó Island, Lower Amazon, Brazil

Author(s): Salvatore Siciliano, Renata Emin-Lima, Alexandra F. Costa, José de Sousa e Silva

Abstract

Carcass of a capybara (Hydrochoerus hydrochaeris) found in Jaranduba farm, Marajó Island, Pará, Brazil, in October 2013. Note the dry vegetation on the back and soil condition. Photo by Rodrigo Baleia.
Carcass of a capybara (Hydrochoerus hydrochaeris) found in Jaranduba farm, Marajó Island, Pará, Brazil, in
October 2013. Note the dry vegetation on the back and soil condition. Photo by Rodrigo Baleia.

Marajó, located in the lower Amazon, Brazil, is one of the largest river islands in the world. Most of the island is subject to tidal or seasonal flooding. Despite its historical, cultural and geographical importance, Marajó Island remains relatively less investigated in terms of mammal diversity, ecology and community structure than the rest of the Amazon. This scenario has motivated the presentation of this list of land mammals of eastern Marajó Island. Two field surveys were conducted in the course of 7-11 December 2012 and 17-25 October 2013 in Jaranduba, Dunas and Ribanceira Farms, northeast portions of Marajó Island. A total of 23 large and medium-sized land mammal species were recorded in the study area. These farms host a representative mammal community of northeastern Marajó, an area lacking previous faunal studies. Human pressure over centuries has deeply modified the environment in Marajó. Therefore, striking evidence of a long human-populated past in this island is in accordance to many other sites throughout the Amazon plain. The result of a land mammal survey in northeastern Marajó is a clear evidence of past and present human interference in the island. Even though Marajó Island has exalted mammal diversity, it will be much higher if long-term studies are effectively implemented.

1. Introduction
Bordering nearly 49,000 square kilometers, Marajó is one of the largest river islands in the world. Most of the island is subject to tidal or seasonal flooding [1]. The local climate can be characterized by two categories: humid tropical, with mean precipitation in the driest month at least 60 mm, and tropical monsoon, with excessive rainfall between January and June. During this period, two thirds of the island is completely flooded [2]-[5]. Annual precipitation ranges between 2500 mm and 4000 mm, with a mean temperature of around 27˚C, and relative humidity bordering on 80%. Rainfall is distributed in two distinct periods, with a pronounced rainy season between December and June, and a dry season between July and November. Despite this rigorous hydrological regime, the vegetation which occupies about 40% of the island is flooded annually and is referred to as a savanna
or flooded grassland [1]-[9].

South American Coati (Nasua nasua) visiting mango trees nearby the big house of Jaranduba Farm in October, 2013. Photo by Rodrigo Baleia.
South American Coati (Nasua nasua) visiting mango trees nearby the big house of Jaranduba Farm in October,
2013. Photo by Rodrigo Baleia.

Long-term interaction between human societies and the environment has found a prodigal field study in Marajó Island [7]. As previously reported, the history of human occupation of the island dates from about 5000 years before present, showing a long background, up to the present, of aquatic resource management [5]-[7]. Seasonally, flooded savannas as a natural fish nursery were from time to time and successfully managed in order to feed indigenous and subsequently early settlers [5]-[7]. The peak of the fishing economy occurred during an archaeological period known as the Marajoara Phase (400-1350 AD), which featured archaeologically known societies that built mounds and dams as part of efficient hydraulic systems, with the underlying purpose of controlling aquatic fauna and water supplies [7]. Such systems, altered during centuries of manipulation, have persisted to the present, even if they have been affected negatively by the interference of cattle, buffalo and horse ranching [4]-[9].

Despite its historical, cultural and geographical importance, Marajó Island remains relatively less investigated in terms of mammal diversity, ecology and community structure than the rest of the Amazon. Early investigations were carried out by naturalists at the end of the 19th century and the beginning of the 20th century [10]. There has been an effort to collect in the region in the last decades and specimens have been deposited in the mammals’ collection of Museu Nacional, Rio de Janeiro and Museu Paraense Emílio Goeldi, in Belém. Despite such efforts, only in the last decade some mammal species have been recorded for the first time in the Marajó Island. Still, some unresolved questions on the occurrence of two primate species [11] [12] and two cervids [11] [13]-[15] remain.

It is remarkable that Marajó Island, specifically its northeast portion and coastline, has been scarcely surveyed in terms of mammal diversity. Hence, faunal inventories in this particular section of the island are sparse, and are mostly restricted to primates and bats [16]-[26]. This scenario has motivated the presentation of this list of land mammals of eastern Marajó Island.

Source:

Journal: Natural Resources
DOI: 10.4236/nr.2015.61005 (PDF)
Paper Id: 53527 (metadata)

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