A STUDY OF THE ECOLOGY OF THE NAMAQUA SANDGROUSE AND OTHER ARID-ZONE BIRDS PENN LLOYD Thesis Presented for the Degree of DOCTOR OF PHILOSOPHY in the Percy Fitzpatrick I nstitute of African Ornithology UNIVERSITY OF CAPE TOWN February 1998' The copyright of this thesis vests in the author. No quotation from it or information derived from it is to be published without full acknowledgement of the source. The thesis is to be used for private study or non- commercial research purposes only. Published by the University of Cape Town (UCT) in terms of the non-exclusive license granted to UCT by the author. "Part of facing up to the realities and complexity of nature is admilting that any approach we take will be incomplete, imperfect. provisional, experimental. The important thing is 10 try: Stephen Budiansky in Nature's Keepers And here I Iry I dedicate this thesis to my mother COLLEEN LLOYD for her many sacrifices to ensure my first-class education. and to DEKKER and SIKKIE STADLER whose hospitality and support kept me sane and made much of this study possible. I TABLE OF CONTENTS ABSTRACf ........................................................................................................................................................... ] ACKNOWLEDGEMENTS ................................................................................................................................. 0 CHAPTERl GENERAL INTRODUCfION ............................................................................................................................ 1 THE NAMAQUA SANDGROUSE ............................................................................................................................ 1 OTHERARI[i..ZONE BIRDS .................................................................................................................................... 2 CHAPTERl THE BREEDING BIOLOGY OF THE NAMAQUA SANDGROUSE ........................................................... 4 SUMMARY .......................................................................................................................................................... 4 INTRODUCTION ................................................................................................................................................... 4 STUDY AREA AND METHODS ............................................................................................................................... 5 RESULTS ..................................................................................................................... , ....................................... 8 Nest site and nest construction ... ................................................................................................................... 8 The laying period .......................................................................................................................................... 8 Incubation ............................................................................ ~ ........................................................................ 9 Hatching ...................................................................................................................................................... 10 Nest predation and nesting success ............................................................................................................. 11 . Chick development and survival ................................................................................................................. 14 DISCUSSION ...................................................................................................................................................... 17 Egg laying. incubation and hatching .......................................................................................................... 17 Nesting success .. .......................................................... ,............................................................................... 18 Chick development and survival ................................................................................................................. 19 Sex ratios ..................................................................................................................................................... 20 Conservation concerns ................................................................................................................................ 21 CHAPTER 3 INVESTIGATOR EFFECfS ON THE NESTING SUCCESS OF ARlD-ZONE BIRDS ............................ 3l SUMMARY ........................................................................................................................................................ 31 INTRODUCTION ................................................................................................................................................. 31 STUDY AREA AND METHODS ............................................................................................................................. 32 RESULTS ........................................................................................................................................................... 34 DISCUSSION ...................................................................................................................................................... 36 CHAPTER 4 NEST SITE SELECfION, EGG PIGMENTATION AND CLUTCH PREDATION IN THE NAMAQUA SANDGROUSE ................................................................................................................................................... 38 SUMMARY ........................................................................................................................................................ 38 INTRODUCTION ................................................................................................................................................. 38 STUDY AREA AND METHODS ............................................................................................................................. 39 Nest site .......................................................................................................................................................39 Egg pigmentation ........................................................................................................................ ................ 40 Predator simulation model................. ......................................................................................................... 41 REsULTS ........................................................................................................................................................... 42 Nest site ....................................................................................................................................................... 42 Egg pigmentation ........................................................................................................................................ 44 Predator simulation model. ......................................................................................................................... 47 DISCUSSION ...................................................................................................................................................... 47 Nest site ....................................................................................................................................................... 47 Clutch pigmentation .................................................................................................................................... 48 Predator simulation model .......................................................................................................................... 48 CHAPTERS THE DAILY ACTIVITY PATIERN OF A NON-BREEDING NAMAQUA SANDGROUSE POPULATION.................................................................................................................................................... SO SUMMARY ........................................................................................................................................................ 50 INTRODUCTION ................................................................................................................................................. 50 STUDY AREA AND METHODS ............................................................................................................................. 5 1 RESULTS ........................................................................................................................................................... 52 DISCUSSION ...................................................................................................................................................... 54 CHAPTER 6 THE DIET AND NUTRITION OF THE NAMAQUA SANDGROUSE ....................................................... S6 SUMMARY ......................................................................................................................................................... 56 INTRODUCTION ................................................................................................................................................. 56 METHODS ......................................................................................................................................................... 57 Diet .............................................................................................................................................................