Diet and Life-History Traits of Savannah Dwelling Waterbirds in Southern Africa: Implications for Their Conservation Status

Tawanda Tarakini,Innocent Mabika,Peter Mundy,Hervé Fritz,Tongayi Mwedzi

doi:10.3390/birds2020013

Abstract

This study evaluates the relative contribution of reproduction-based life history traits and diet to the population trends in waterbirds from southern Africa. Life history traits (clutch size, incubation period, fledging time, body mass and generation length), diet (prey weight, body lengths and number of taxa represented in its diet (NTD)) and conservation status (declining/not declining) of 163 waterbird species were reviewed. An index of diet generalism was created based on NTD. Cluster analysis was applied on life history traits to define groups of waterbirds. Binomial regressions were used to test if population trends were different across cluster groups and diet variables. Four clusters of waterbirds were defined, with most waterfowl clustering together. Species that feed on small and large prey had higher probabilities of declining (0.17 and 0.26, respectively) compared to those feeding on medium-sized prey (0.08). Amphibians, coleopterans, crustacea, molluscs and tunicates were used by species in all clusters, and the risk of waterbird populations declining further are high given the current dwindling of the prey base. The large proportions of declining species (61%) in waterbirds, which have constrained habitats, calls for continued efforts to mitigate disturbances to wetlands.

Highlights

The southern African region is endowed with a variety of waterbirds that feed in various coastal and inland habitats [1]
Knowing that waterbird prey are responding at different rates to these global shifts [4], an exploration of the traits and diet requirements of species that are associated with various conservation states can provide vital information to be used for conservation planning
Most life history traits in birds, in particular those linked to reproduction, are positively related to individual body mass [5,6] and generation length [7]

Summary

Introduction

The southern African region is endowed with a variety of waterbirds that feed in various coastal and inland habitats [1]. Traits that promote dietary flexibility in a species can be beneficial given the global shifts in habitats [2], resources and climate [3]. Knowing that waterbird prey are responding at different rates to these global shifts [4], an exploration of the traits and diet requirements of species that are associated with various conservation states can provide vital information to be used for conservation planning. Particular characteristics in life history traits could make some species more vulnerable to population declines if environmental conditions change [9]. Several studies have documented the dietary requirements of waterbird species [1,10,11] and species with narrow diet niches (specialist) could be more prone to changes in habitat and resources [2,12]

Methods

Results

Discussion

Conclusion