BSTRACT

An assessment of the distribution and feeding ecology in amphibian (anuran) species, It was conducted between March 2017 and April 2017. Visual encounter survey and capture methods were used to study the distribution of anurans. Captured animals were degutted and their gut contents were used in the study of feeding ecology. A total of 13 species of amphibian belonging to 7 families of order anuran were found to exist in Kimboza forest. The highest occurrence of anurans (70%) was recorded in areas where forest border with farms and along Kimboza forest streams. The study showed that there was no significant variation of occurrence of anurans among different habitats in Kimboza forest (Q=11; DF =6; P=0.096). On the other hand, about 462 prey items belonging to 10 food groups were found in the guts of 93 captured anurans and the most abundant food groups were Isoptera and Hymenoptera while Coleoptera were the most frequent. There were no significant differences in the anurans’ diet (composition, diversity and preferences) among different habitats of the forest (along boundaries and within the forest) but significant differences were found between the upper fragment and the lower fragment of the forest. The similarities of diets of anurans in different habitats along forest boundaries and within the forest were due to the fact that most of anurans were generalist predators. The study provides a preliminary estimation of the actual diet of anurans and establishes a general distribution pattern for these species in Kimboza forest. These findings are important for understanding and management of anurans in Kimboza Forest Reserve. Further studies focused on dry season and nocturnal species are recommended so as to come up with a complete description of the distribution and feeding ecology of anuran species of Kimboza Forest Reserve.

CHAPTER ONE

1.0  INTRODUCTION

1.1  Background Information

Amphibians are mostly considered to be generalist predators (Pough et al., 2004). Some species have a narrow diet or even specialise on certain prey categories. For example a number of species of Microhylids and Dendrobatids, have specialised on eating ants and termites (Hirai and Matsui, 2000; Solé et al., 2002). Nevertheless, within the generalist specialist continuum, there are several species that have highly varied diets, but with concentrated consumption of a few prey categories (Siqueira et al., 2006; Lima et al., 2010).

The differences in diet composition are probably due to variation of habitats abundance and diversity of prey (Sousa and Avila, 2015). The type and quality of habitat tend to influence the distribution and feeding preferences in anurans (Ferenti et al., 2010). For instance, anthropogenic disturbance of habitat can lead to variation in composition and abundance of resources, and as a result some species may adjust their diets. Generalist species are a good example of such species as they have the ability to adjust their diets to the more available resources in order to improve their energy uptake and fitness (Gray and Smith, 2005; Williams et al., 2006; Falico et al., 2012). However, the highly specialised species or those with specific and fixed trophic requirements have greater difficulties of coping with environmental alterations which usually cause changes to prey availability (Williams et al., 2006).

Amphibians (anurans) are distributed in different forest types and in different microhabitats. There are many factors that influence the differences in the distribution of

anuran species in their habitats. For example, diet was found to be one of the factors by Allmon (1991) who observed that the distribution patterns of forest leaf litter anurans was linked to prey availability. Further, there are other factors which are reported to influence the differences of distribution of anuran species in the same habitat including environmental structure (Menin et al., 2005), differential utilisation of microhabitat and foraging strategy (França et al., 2004).

Amphibians are an abundant and diverse component of many terrestrial and freshwater ecosystems where they play critical roles in food webs often linking terrestrial and aquatic ecosystems (Pradhan et al., 2014). The rapid and ongoing reduction of amphibians’ species richness worldwide has added urgency for dedicated efforts to understand the ecological roles that they play within ecosystems (Connelly et al., 2011). Threats to amphibians are particularly evident in the coastal region of Tanzania, where forests continue to decline as a consequence of expanding populations and proximity to urban areas (Barratt et al., 2014). Feeding can be an important parameter for the understanding of anuran life history, population fluctuations, the impact of habitat modification on those populations especially for species that inhabit endangered areas, and as an indicator of the quality of the environment in which the amphibians live (Santos et al., 2004 ; Kovacs et al., 2007).

1.2  Problem Statement and Justification of the Study

Amphibian population is steadily declining where by it is approximated that 97 percent of the existing species are found in protected areas (Milligan et al., 2014). The main reasons for the population decline include habitat loss and degradation (Milligan et al., 2014). Yet, amphibians have not been given appropriate attention with regard to their ecological roles

in ecosystems to where they exist (Valencia-Aguilar et al., 2013). This, among many

reasons, is brought about by low level of understanding regarding the roles that amphibians play in ecosystems (Bickford et al., 2010; Hocking and Babbitt, 2014). A good example is in Kimboza forest reserve where there is poor information on amphibians due to little attention with regard to their important ecological roles (Bayliss, 1994; Clarke and Dickinson, 1995). None of the studies conducted so far have involved the understanding of distribution, dietary composition and feeding preferences of anurans.

Although a few studies exist, Kimboza forest reserve is known to harbor high diversity of amphibians. However, the home ranges and foraging habitats for these species are threatened by increased anthropogenic disturbances resulting from illegal agriculture activities in the forest area, timbers and pole harvesting carried out by people in the villages surrounding the forest (Kacholi, 2013). Since, amphibians are important components in trophic cascades of ecosystems, their vanishing may bring crucial effects on ecosystem functioning (Mohneke and Rödel, 2009). Accordingly, besides available basic ecological and biological data on amphibians, studies on feeding ecology can help to open up abundant but hidden ecological information which can be used to estimate the effects of loss of amphibians on ecosystem functioning (Duffy, 2002; Whiles et al. 2006). Furthermore, information on amphibian distribution is essential in understand where species occur and to be able to determine sound conservation strategies of the species (Dodd and Smith, 2003). Therefore, this study was aimed at unveiling the distribution and feeding ecology of Amphibians of Kimboza forest reserve. Besides being the first of its kind in Tanzania for the class, the information about predation competition and trophic cascades is of great use in furthering understanding of amphibian ecology.

1.3  Objectives of the Study

1.3.1  Overall objective

The overall aim of the study was to describe the distribution and feeding ecology of amphibian (anuran) species in Kimboza Forest Reserve.

1.3.2  Specific objectives

The specific objectives of the study were:

1. To examine the distribution of anurans in different habitats across Kimboza Forest Reserve.
   1. To analyze the anuran dietary composition.

1. To examine the anuran dietary diversity.

1. To assess the influence of habitat on the feeding preferences of anuran species in Kimboza forest Reserve.

1.3.3  Research questions

To realize the specific objectives, the study was guided by these questions:

1. How are anurans species distributed across different habitats along boundaries and within Kimboza forest?
2. What is the food composition of anuran species in Kimboza forest?

1. How diverse is the food composition of anuran species in Kimboza forest?

How do different habitats along boundaries and within the forest influence the feeding preference of anuran species in Kimboza forest?

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