The Provisioning of Nestlings Py Parent
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THE PROVISIONING OF NESTLINGS BY PARENT RHINOCEROS AUKLETS Douglas Frank Bertram B.Sc., University of Victoria, 1984 THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in the Department of Biological Sciences @ Douglas Frank Bertram 1988 SIMON FRASER UNIVERSITY January 1988 All rights reserved. This work may not be reproduced in whole or in part, by photocopy or other means, without permission of the author. APPROVAL Name : Douglas Frank Bert ram Degree: Master of Science Title of Thesis: The Provisioning of Nestlings by Parent Rhinoceros Auklets,(Cerorhinca monocerata). Examining Committee: Chairman: Dr. 1~3.Yam~iZwAssistant Professor, Senior SupervisorC Dr. A.S. haresLau, Assistant Professor __L -rmeer, Research ~ci4t,Canadian Wildlife Service Dr. U.D. Koitberg, Assistant Professor, Biological Sciences Dept., Simon Fraser University, Publfic Examiner Dr. N.A.M. verbekk; Associat~~roiessor, Bid logical Sciences Dept., Simon Fraser University, Public Examiner Date Approved JA~15 1588 PART IAL COPYR IGHT L ICENSE I hereby grant to Simon Fraser Unfverslty the right to lend my thesis, proJect or extended essay (the title of which is shown below) to users ot the Simon Fraser University Library, and to make partial or single copies only for such users or in response to a request from the library of any other unlversity, or other educational institution, on its own behalf or for one of its users. I further agree that permission for multiple copying of this work for scholarly purposes may be granted by me or the Dean of Graduate Studies. It is understood that copying or publication of this work for financial gain shai I not be a1 lowed without my written permission. Title of Thes i s/Project/Extended Essay The Provisioning of Nestlings by Parent Rhinoceros Auklets (Cerorhinca monoceata) Author ( sere ABSTRACT Parental provisioning of nestling rhinoceros auklets (Cerorhinca monocerata) was studied on Lucy Island, B.C. from 1985 to 1987. There was considerable inter-year variation in the amount of food delivered as chicks aged. In 1985 the amount of food delivered to chicks in the latter half of their nesting period dropped off sharply and continued to decline until fledging. A similar reduction in provisioning was noted for chicks of the same age range in 1986, although the rate of decline was much less than in 1985. In 1987 no decline in provisioning occurred with chick age, although the data combined for all years indicate that this trend is significant. No consistent differences were observed in the size of food loads delivered to early and late hatched chicks of the same age, i suggesting that a seasonal decline in food availability was not ' the cause of the reduced pee-fledging feeding rate. I suggest the decline in provisioning is the manifestation of a parental life history tactic in which adults increase their probability of survival by making fewer visits to the colony when chicks are alder. Chick growth rates decreased from 1985 to 1987. Independent evidence suggests that growth rates of nestling rhinoceros auklets can act as an indicator of marine feeding conditions. Inter-annual differences in the amount of food delivered as chicks aged are hypothesized to result from variations in food availability, inferred from the measurements of chick growth iii , rate. Chick exchange experiments in 1986 did not induce parents to change the amount of food delivered to either larger or smaller foster chicks. In a more extensive experiment in 1987, parents delivered less to small foster chicks and more to larger chicks when young and middle aged chicks were exchanged. As in 1986, parents did not respond to foster chicks of the middle to late age range by changing food deliveries. These results are discussed in terms of parent-offspring conflict. ACKNOWLEDGEMENTS I would like to thank my senior supervisor Dr. Ron Ydenberg for his academic guidance and enthusiasm throughout the development of this study. Thanks must also go to my committee members, Drs. Mart Gross, Alton Harestad, and Kees Vermeer for their suggestions and support. This thesis would not have been possible without the backing of the Canadian Wildlife Service who provided financial support, manpower and all of the necessary field equipment. In particular, I am indebted to Gary Kaiser who coordinated the field operation and whose home served as a half-way-house for most of the incoming and outgoing volunteers. I would also like to thank Dr. G.E.J. Smith (C.W.S.) for statistical advice and / his help in developing the camp chick growth model. Few people know the thrill of seeing rhinoceros auklets visit a colony at night, or have experienced the agony of attempting to locate an uncooperative chick in an intricate burrow during a rainstorm. The following people do however: Matt Amedro, David Beadle, Rosalind Chaundy, Jon Curson, Michael Force, Iv6n Jimbnez M., Anne Labbb, Roger McMichael, CristiAn Samper K., Terry Sullivan, Katherine Thomas, Richard Wakelam, Andrew Whittaker, and Clive Welham. I thank them all for what was sometimes arduous field work. The Canadian Coast Gaurd in Prince Rupert provided friendly cooperation which made for safer and easier field seasons. I am grateful to the crews of the M.V. Cloo Stung and the M.V. Point Henry for transporting gear and people to and from the Lucy Islands. I owe special thanks to the light keepers on Lucy, particularly Don and Kathy Richards for their warm hospitality, logistic support and great parties. I also wish to thank the people at the Department of Fisheries and Oceans at Seal Cove in Prince Rupert for allowing me to moor boats there. I thank Mark Abrahams, Ralph Cartar, Mike Dehn, Simon Emms, Scott Forbes, Darren Gillis, Guy Martel, Peter Nonacs, and Clive Welham for their advice, friendship and general aberrant behaviour. In addition to the Canadian Wildlife Service the project was funded by NSERC Grant No. U0461 to Ron Ydenberg, and the following scholarships: Anne Vall6e Ecological Fund Scholarhip (1985)~NSERC PGSl (1985-1986), NSERC PGSIR (1986-87). I thank my mother for making the hoods for the chicks on short notice and for putting up with me as a teenager. I owe special thanks to my wife, Sandi, for supporting my field habit and for assisting me throughout. I could not have done it without her. To my father vii TABLE OF CONTENTS Approval .................................................... ii Abstract ................................................... iii Acknowledgements ....................................... v List of Tables ........................................ x List of Figures ........................................ xi I . GENERAL INTRODUCTION .................................... 1 I1 . GENERAL METHODS ........................................ 7 Study Species ........................................... 7 Study Site .............................................. 8 Study Methods .......................................... 11 I I I . PROVI SI ON1 NG BY PARENTAL RHINOCEROS AUKLETS ............ 15 INTRODUCTION ........................................... 15 . The Environmental Hypothesis ........................ 17 The Preeoeial Growth Hypothesis ..................... 18 The Parental Tactic Hypothesis ...................... 19 METHODS ................................................ 21 RESULTS ................................................ 23 DISCUSSION ............................................. 34 IV . CHICK GROWTH ........................................ 40 INTRODUCTION ........................................... 40 METHODS ............................................ 44 Supplementary Feeding Experiment .................... 44 Chick Growth ........................................ 45 Composite Growth Curves ............................. 47 RESULTS ................................................ 47 viii Supplementary Feeding ............................... 48 Intra-year Comparisons .............................. 48 Inter-year Comparisons .............................. 52 DISCUSSION ............................................. 55 V . INFLUENCES ON PARENTAL PROVISIONING .................... 62 INTRODUCTION ........................................... 62 METHODS ................................................ 65 Chick Manipulations ................................. 65 Estimating burrow loads from camp chick growth ...... 68 Camp Chick Growth Model ............................. 70 RESULTS ................................................71 Manipuchick ........................................ 71 Camp Chicks ........................................ 71 Fostering Experiments ............................... 73 DISCUSSION .......................................... 76 Fostering Experiments ............................... 76 Manipuchick ......................................... 82 VI . GENERAL DISCUSSION AND CONCLUSIONS ..................... 84 LITERATURE CITED ......................................... 90 APPENDI'X 1: An estimate of the power of 'the analysis in Table 3.2 .............................................. 96 APPENDIX 2: The Camp Chick Growth Model ..................... 98 LIST OF TABLES Table Page 3.1 Coefficients of parameters of the provisioning curves in 1985-7 ........................................... 30 3.2 Ranks of burrow loads delivered to chicks hatched at different times in the season. ...................... 31 3.3 Comparison of bill load size on different dates during the season. ......................................... 35 4.1 Comparison