Population and density estimate of Black Rat (Rattus rattus) in Mangrove Forests in Hara Biosphere Reserve - Hormozgan Province
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Abstract
Population and density estimate of Black Rat in Mangrove forests was conducted by two independent procedures, including Seber-Jolly and Catch-Effort Methods. A selected trapping area with 15 hectares was studied. First, 60 cage traps for Seber-Jolly and then 80 cage traps for Catch-Effort method installed in the trapping area. We used color earrings and numerical rings for marking the captured individuals. Seber-Jolly method was performed in seven steps which population was estimated 68.5, 96.9, 105.8, 61.7 and 73.6 with densities of 4.1 to seven Rats/ha for steps two to six respectively. Catch-Effort method performed in six steps and population estimate was 89.3 with densities of 5.9 Rats/ha. For comparing the population estimates with the total population captured in the trapping area, the total number of rats was 96 with density of 6.4 Rats/ha. Considering the results, around 4-7 Black Rats survive in every single hectare of Mangrove forests of the study site, which states low differences between the results of Seber-Jolly, Catch-Effort and total count methods. All of these methods appear to be suitable for population-estimate in this habitat, but Catch-Effort method is the most recommended way to study Black Rats in Mangrove forests, due to lower standard error. Black Rat is an exotic and pest species in this habitat and excluding them for scientific reasons would not damage this ecosystem. The other advantages of the Catch-Effort method is its low-cost and efficiency, which could lead us to a total population estimate of the area.
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