DOCSLIB.ORG

The Reproductive Biology and Temporal Distribution of a Great Egret and Nankeen Night Heron Colony at the Perth Zoo

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Reproductive Biology and Temporal Distribution of a Great Egret and Nankeen Night Heron Colony at the Perth Zoo Edith Cowan University Research Online Theses: Doctorates and Masters Theses 1-1-2001 The reproductive biology and temporal distribution of a great egret and nankeen night heron colony at the Perth Zoo Robyn Phillimore Edith Cowan University Follow this and additional works at: https://ro.ecu.edu.au/theses Part of the Ornithology Commons Recommended Citation Phillimore, R. (2001). The reproductive biology and temporal distribution of a great egret and nankeen night heron colony at the Perth Zoo. https://ro.ecu.edu.au/theses/1046 This Thesis is posted at Research Online. https://ro.ecu.edu.au/theses/1046 Edith Cowan University Copyright Warning You may print or download ONE copy of this document for the purpose of your own research or study. The University does not authorize you to copy, communicate or otherwise make available electronically to any other person any copyright material contained on this site. You are reminded of the following: Copyright owners are entitled to take legal action against persons who infringe their copyright. A reproduction of material that is protected by copyright may be a copyright infringement. Where the reproduction of such material is done without attribution of authorship, with false attribution of authorship or the authorship is treated in a derogatory manner, this may be a breach of the author’s moral rights contained in Part IX of the Copyright Act 1968 (Cth). Courts have the power to impose a wide range of civil and criminal sanctions for infringement of copyright, infringement of moral rights and other offences under the Copyright Act 1968 (Cth). Higher penalties may apply, and higher damages may be awarded, for offences and infringements involving the conversion of material into digital or electronic form. EDITH COWAN UNIVERSITY LIBRARY The Reproductive Biology and Temporal Distribution of a Great Egret and Nankeen Night Heron Colony at the Perth Zoo. By Robyn Phillimore A Thesis Submitted in Partial Fulfilment of the Requirements forthe A ward of Master of Science (Environmental Management) at the School of Natural Sciences, Faculty of Science, Technology and Engineering, Edith Cowan University. Date of Submission: 15 June2001 USE OF THESIS The Use of Thesis statement is not included in this version of the thesis. Abstract A colony of Great Egrets (Ardea alba) and Nankeen Night Herons (Nycticorax caledonicus) has existed at the PerthZoo in Metropolitan Perth for over 25 years. The colony is particularly significant for the conservation and management of Great Egrets in W estem Australia as it is the only colony located in the Metropolitan area. Baseline information of their breeding biology was needed to facilitate the development of management guidelines for the zoo colony. Foraging behaviour was used to highlight specific adaptations in hunting strategies and diet. However, it was not possible to observe foraging Nankeen Night Herons as they forage at night. Therefore, another species, the Little Egret, was selected to highlight specificadaptations. From 1997 to 1999 the reproductive biology of the Great Egret and Nankeen Night Heron was assessed. The number of N ankeen Night Herons nesting at the Perth Zoo from 1996 to 1998 increased, while the number of Great Egrets declined. Both species nested in tall trees but only Great Egrets were specific in their choice of nesting tree species. Horizontal nest placement appeared to be influenced by body size. Great Egrets had a larger clutch size than the NankeenNight Heron, and a slightly higher offspring mortality rate. There was some indication that Great Egrets may use the colony as an informationcentre about productive feedinggrounds. Foraging behaviour of Great Egrets and Little Egrets was recorded at six wetlands in the Perth Metropolitan area. Great Egrets were found to be mainly searchers, using 'stand and wait' and 'walk slowly' foragingbehaviours, while the Little Egret was a 'pursuer', hunting by 'walking slowly', 'walking quickly' and 'pursuing prey'. Great Egrets 3 caught a greater number of prey per attempt at capture, feeding on larger sized prey, mostly fish. Little Egrets fed on smaller sized prey, mostly invertebrates. Habitat type and wind speed had a significant effect on striking success of Great Egrets. Cloud cover, wind speed and direction had a significant effect on striking success of Little Egrets. The larger body size of the Great Egret allowed them to forage in deeper water thanthe Little Egret. Baseline information provided by this study has assisted in the development of management recommendations forthe zoo colony and forGreat Egrets and Little Egrets in the Perth Metropolitan area. To provide long-term information on overall population trends for the colony, regular counting and population distribution mapping of Great Egrets and Nankeen Night Herons is needed. To prevent Nankeen Night Heron numbers elevating and possibly encroaching on the nesting habitat of the Great Egret, food available in the zoo grounds should be reduced by covering caged animals' food. Planting of nesting trees within the existing colony may be required to enable the number of Great Egrets nesting in the Perth Zoo to increase. To prevent disturbances to birds when foragingwithin Perth wetlands, sites that are reachable by humans should be fenced off,or access restricted. 4 Declaration I certify that this thesis does not, to the best of my knowledge and belief: 1. incorporate without acknowledgement any material previously submitted for a degree or diploma in any institution of higher education; ii. contain any material previously published or written be another person except where due referenceis made in the text; or 111. contain any defamatory material. 5 Acknowledgements I thank Western Power staff Carl Phillimore, Dave Ozie, Ken Cheeseman and Neville Allen for driving the cherry picker. Thanks also to David Luu who assisted me while up in the cherry picker. I am extremely grateful to the Perth Zoo for allowing me to undertake research on the zoo grounds. In particularI give special thanks to Neil Hamilton and the rest of the bird department for feeding and caring for abandoned Great Egret chicks, assisting me in fieldwork, and providing endless advice. I thank the Western Australian Museum, in particular Ron Johnstone, for the use of the egret andheron specimens. I also thank Birds Australia for their advice and information as well as undertaking a survey on Great Egrets in the Perth Metropolitan area. I thank Judy Blyth for her beautiful line drawings of the Great Egret, Little Egret and Nankeen Night Heron. I would like to thank my supervisors Dr Mark Lund, Dr Allan Burbidge (CALM) and Prof. Harry Recher for their advice, time and patience, as well as reading numerous drafts of my thesis. Thankyou also to others who have provided advice and assistance with my thesis: Elaine Pascoe, Leonie Monks, Val English, Nadine Guthrie, John Blyth and Sandy Griffin. 6 Table of Contents ABSTRACT ..................................................................................................................... 3 DECLARATION ............................................................................................................. 5 ACKNOWLEDGEMENTS........................................................................... ................. 6 TABLE OF CONTENTS ................................................................................................ 7 LIST OF TABLES .......................................................................................................... 9 LIST OF FIGURES ...................................................................................................... 12 CHAPTER 1 GENERAL INTRODUCTION............................................................. 16 1.1 Wading Birds ...................................................................................................... 16 1.2 Breeding Biology ................................................................................................ 20 1.3 Foraging Behaviour ............................................................................................ 24 1.4 The Perth Zoo Colony ........................................................................................ 27 1.5 Aims and objectives ............................................................................................ 29 CHAPTER 2 THE PERTH ZOO COLONY .............................................................. 30 2.1 Introduction...... .................................................................................................. 30 2.2 Methods .............................................................................................................. 32 2.3 Results ................................................................................................................ 41 2.4 Discussion ........................................................................................................... 59 2.5 Conclusion .......................................................................................................... 68 CHAPTER 3 FORAGING ECOLOGY ...................................................................... 70 3.1 Introduction..... ................................................................................................... 70 3.2 Methods .............................................................................................................. 72 3.3 Results ................................................................................................................80
Load more

Recommended publications
  • Yellow-Crowned Night-Heron Nyctanassa Violacea
    Yellow-crowned Night-Heron Nyctanassa violacea Bob Moul Photo CURRENT STATUS: In Pennsylvania, the yellow-crowned night-heron is listed as state endangered and protected under the Game and Wildlife Code. Nationally, they are not listed as an endangered or threat- ened species. All migratory birds are protected under the federal Migratory Bird Treaty Act of 1918. POPULATION TREND: Yellow-crowned night-herons (Nyctanassa violacea) are one of the state’s rarest nesting birds). They are rare, regular visitors or residents in the Piedmont region of southeastern Penn- sylvania (all or parts of Bucks, Northampton, Lehigh, Berks, Lebanon, Lancaster, Dauphin, York, Adams and Cumberland counties), where they breed locally. In the coastal plain area along the Delaware River near Philadelphia, they are rare, irregular visitors. They are accidental visitors elsewhere in the state, particularly in late summer following the breeding season. Currently, the only known breeding sites are in Cumberland, Dauphin and York counties. They nest singly and in loose colonies regularly along Conodo- quinet Creek. A few yellow-crowned night-herons also nest on private property in an urban setting in Dauphin County and at Kiwanis Lake in York. Nests were once also found along Conestoga and Little Conestoga creeks in Lancaster County. Surveys in the 1990s counted not more than eight to 12 nests in any year in the state. Yellow-crowned night-herons were first listed as threat- ened species in 1990 because of their limited popula- tion and restricted range. They were downgraded to endangered in 1999 because of their small and vulner- able population. IDENTIFYING CHARACTERISTICS: Adults are me- dium-sized, 22 to 28 inches in length from bill tip to tail tip, gray with a black head and whitish cheek patch and crown.
    [Show full text]
  • The Solomon Islands
    THE SOLOMON ISLANDS 14 SEPTEMBER – 7 OCTOBER 2007 TOUR REPORT LEADER: MARK VAN BEIRS Rain, mud, sweat, steep mountains, shy, skulky birds, shaky logistics and an airline with a dubious reputation, that is what the Solomon Islands tour is all about, but these forgotten islands in the southwest Pacific also hold some very rarely observed birds that very few birders will ever have the privilege to add to their lifelist. Birdquest’s fourth tour to the Solomons went without a hiccup. Solomon Airlines did a great job and never let us down, it rained regularly and we cursed quite a bit on the steep mountain trails, but the birds were out of this world. We birded the islands of Guadalcanal, Rennell, Gizo and Malaita by road, cruised into Ranongga and Vella Lavella by boat, and trekked up into the mountains of Kolombangara, Makira and Santa Isabel. The bird of the tour was the incredible and truly bizarre Solomon Islands Frogmouth that posed so very, very well for us. The fantastic series of endemics ranged from Solomon Sea Eagles, through the many pigeons and doves - including scope views of the very rare Yellow-legged Pigeon and the bizarre Crested Cuckoo- Dove - and parrots, from cockatoos to pygmy parrots, to a biogeographer’s dream array of myzomelas, monarchs and white-eyes. A total of 146 species were seen (and another 5 heard) and included most of the available endemics, but we also enjoyed a close insight into the lifestyle and culture of this traditional Pacific country, and into the complex geography of the beautiful forests and islet-studded reefs.
    [Show full text]
  • Birding Oxley Creek Common Brisbane, Australia
    Birding Oxley Creek Common Brisbane, Australia Hugh Possingham and Mat Gilfedder – January 2011 [email protected] www.ecology.uq.edu.au 3379 9388 (h) Other photos, records and comments contributed by: Cathy Gilfedder, Mike Bennett, David Niland, Mark Roberts, Pete Kyne, Conrad Hoskin, Chris Sanderson, Angela Wardell-Johnson, Denis Mollison. This guide provides information about the birds, and how to bird on, Oxley Creek Common. This is a public park (access restricted to the yellow parts of the map, page 6). Over 185 species have been recorded on Oxley Creek Common in the last 83 years, making it one of the best birding spots in Brisbane. This guide is complimented by a full annotated list of the species seen in, or from, the Common. How to get there Oxley Creek Common is in the suburb of Rocklea and is well signposted from Sherwood Road. If approaching from the east (Ipswich Road side), pass the Rocklea Markets and turn left before the bridge crossing Oxley Creek. If approaching from the west (Sherwood side) turn right about 100 m after the bridge over Oxley Creek. The gate is always open. Amenities The main development at Oxley Creek Common is the Red Shed, which is beside the car park (plenty of space). The Red Shed has toilets (composting), water, covered seating, and BBQ facilities. The toilets close about 8pm and open very early. The paths are flat, wide and easy to walk or cycle. When to arrive The diversity of waterbirds is a feature of the Common and these can be good at any time of the day.
    [Show full text]
  • OBSERVATIONS on a GREAT EGRET Ardea Alba and NANKEEN NIGHT HERON Nycticorax Caledonicus COLONY at the PERTH ZOO, WESTERN AUSTRALIA
    Corella, 2004, 28(3): 82-86 OBSERVATIONS ON A GREAT EGRET Ardea alba AND NANKEEN NIGHT HERON Nycticorax caledonicus COLONY AT THE PERTH ZOO, WESTERN AUSTRALIA ROBYN L. PHILLIMORE' and HARRY F. RECHER2 'School of Natural Sciences, Edith Cowan University, Joondalup, Western Australia, Australia 6027 email: [email protected]: [email protected] 'Corresponding author. Present address: P.O. Box 154, Brooklyn, New South Wales, Australia 2083 Received: I I Augusr 2003 A colony of Great Egrets Ardea alba and Nankeen Night Herons Nycticorax caledonicus has existed at the Perth Zoo, Western Australia for over 25 years. The colony of egrets is one of very few in the region and hence is significant for the conservation and management of Great Egrets in Western Australia. From 1996 to 1998, surveys were conducted to determine the number of breeding pairs, clutch size, breeding success, and nest site selection of birds in the colony. Most observations were ground based, but a 30-metre cherry picker was used to inspect nests and determine clutch size. One hundred and thirty night heron and 49 egret nests were found in 1996; 92 night heron and 41 egret nests in 1997; and, 153 night heron and 36 egret nests in 1998. Nesting commenced in September, with peak numbers in early November. Both species nested in tall trees well above zoo visitors and animals. Egrets nested only in pines, whereas night herons nested mainly in figs. Great Egrets had an average clutch size of 2.6-2.7 by early November compared with a clutch of 1.6-1.8 for Nankeen Night Herons.
    [Show full text]
  • Bird Vulnerability Assessments
    Assessing the vulnerability of native vertebrate fauna under climate change, to inform wetland and floodplain management of the River Murray in South Australia: Bird Vulnerability Assessments Attachment (2) to the Final Report June 2011 Citation: Gonzalez, D., Scott, A. & Miles, M. (2011) Bird vulnerability assessments- Attachment (2) to ‘Assessing the vulnerability of native vertebrate fauna under climate change to inform wetland and floodplain management of the River Murray in South Australia’. Report prepared for the South Australian Murray-Darling Basin Natural Resources Management Board. For further information please contact: Department of Environment and Natural Resources Phone Information Line (08) 8204 1910, or see SA White Pages for your local Department of Environment and Natural Resources office. Online information available at: http://www.environment.sa.gov.au Permissive Licence © State of South Australia through the Department of Environment and Natural Resources. You may copy, distribute, display, download and otherwise freely deal with this publication for any purpose subject to the conditions that you (1) attribute the Department as the copyright owner of this publication and that (2) you obtain the prior written consent of the Department of Environment and Natural Resources if you wish to modify the work or offer the publication for sale or otherwise use it or any part of it for a commercial purpose. Written requests for permission should be addressed to: Design and Production Manager Department of Environment and Natural Resources GPO Box 1047 Adelaide SA 5001 Disclaimer While reasonable efforts have been made to ensure the contents of this publication are factually correct, the Department of Environment and Natural Resources makes no representations and accepts no responsibility for the accuracy, completeness or fitness for any particular purpose of the contents, and shall not be liable for any loss or damage that may be occasioned directly or indirectly through the use of or reliance on the contents of this publication.
    [Show full text]
  • California Red-Legged Frog (Rana Aurora Draytonii)
    AMPHIBIANS California Red-Legged Frog (Rana aurora draytonii) California Red-Legged Frog (Rana aurora draytonii) Status State: Meets requirements as a “rare, threatened or endangered species” under CEQA Federal: Threatened Critical Habitat: Designated in 2001 (USFWS 2001) but rescinded in 2002 by court order except for one unit in the Sierra Nevada; proposed again in 2004 (USFWS 2004) Population Trend Global: State endemic; declining State: Declining Within Inventory Area: Apparently stable in some areas Data Characterization The location database for the California red-legged frog (Rana aurora draytonii) within its known range in California includes 419 data records dated from 1919 to 2001. Of these records, 344 were documented within the past 10 years; of these, 203 are of high precision and may be accurately located within the inventory area. Approximately 81 of these high-precision records are located within or near the inventory area. These records occur within non-native grassland, riparian forest, riparian woodland, riparian scrub, freshwater marsh, and wetland. A moderate amount of literature is available regarding the California red-legged frog because of its threatened status and the recent trend in global decline in amphibians. Most of the literature pertains to habitat requirements, population trends, ecological relationships, threats, and conservation efforts. A final recovery plan for the California red-legged frog has been published by the U.S. Fish and Wildlife Service (2002). Range The historical range of the California red-legged frog extended along the coast from the vicinity of Point Reyes National Seashore, Marin County, California and inland from Redding, Shasta County southward to northwestern Baja California, Mexico (Jennings and Hayes 1985, Hayes and Krempels 1986).
    [Show full text]
  • Black-Crowned Night-Heron (Nycticorax Nycticorax) William C
    Black-crowned Night-Heron (Nycticorax nycticorax) William C. Scharf Status: Special Concern (MNFI) Detroit Zoo, MI. 6/11/2008 © Joan Tisdale (Click to view a comparison of Atlas I to II) Known by the elegant black and white of its Distribution Black-crowned Night-Herons in Michigan adult plumage and its red-eyed stare, the Black- historically have had their colonies along the crowned Night-Heron is a voracious and shores and islands of Lake Erie, the Detroit stealthy predator of fish, frogs, mice, and River, Lake St. Clair and Lake Huron with new especially young gulls, terns and other birds. colonies since Scharf (1998) expanding into Many potential prey animals should heed its northern Lake Michigan, Lake Huron, the St. “quawk” call in the night. A widespread species, Marys River and eastern Lake Superior. They it is found nesting on every continent except seek nesting on islands or other similar insulated Australia and Antarctica (Davis 1993). They are spots protected from predators. Twelve breeding colonial breeders, and are often found breeding colonies were documented on the Great Lakes and foraging with other species of herons as islands or along the shoreline of the NLP and well as other species of colonial nesting UP during MBBA II. This seems to indicate an waterbirds. increase in northward nesting for this species. A noteworthy coincident change has been that new Suitable wetland habitat for nesting and colonies established in Ontario are northward of foraging influences Black-crowned Night Heron the traditional nesting areas by 72 km (48 mi) distribution. Sites of Black-crowned Night (Cadman 2007).
    [Show full text]
  • The Maintenance Behavior of the Black-Crowned Night Heron
    THE MAINTENANCE BEHAVIOR OF THE BLACK-CROWNED NIGHT HERON GEORGER. MAXWELL AND LOREN S. PUTNAM HIS paper is concerned with a three month study of the maintenance T behavior of the Black-crowned Night Heron (Nycticorax nycticorax) and includes a description and interpretation of the activities observed. Maintenance behavior, as used in this paper includes movements concerned with locomotion, preening, scratching, care of feet, shaking, stretching, defecation, bill-wiping, sleeping, throat pulsation, yawning, resting, and feeding. The Black-crowned Night Heron is well suited to this type of study due to its colonial nesting habit. The work by Meyerriecks (1960) reinforced our interest in herons and this paper follows the style established in his monograph, so that these data may be utilized more easily. Specific com- parisons of night heron with Green Heron behaviors are made whenever the differences or similarities are striking enough to merit them. Some work has been done on the food preference of the night heron (see Palmer, 1962 and Teal, 1965), but little on the feeding behavior of im- mature herons. A detailed description of the behavior leading to the food transfer, as well as the food transfer itself, has not been available. Field observations were made in Foxs’ Marsh on North Bass Island, Ottawa County, Ohio, in western Lake Erie during the summer of 1963. Further observations were planned but the colony failed to breed in the marsh the following year. The marsh, about 1500 feet by 500 feet, is located at the south-west corner of the island. In the past it has been connected with the lake, but due to low water and wave action, it is now separated by a gravel bar.
    [Show full text]
  • The Evolution of Cerebrotypes in Birds
    Original Paper Brain Behav Evol 2005;65:215–230 Received: June 23, 2004 Returned for revision: July 20, 2004 DOI: 10.1159/000084313 Accepted after revision: September 14, 2004 Published online: March 8, 2005 The Evolution of Cerebrotypes in Birds Andrew N. Iwaniuk Peter L. Hurd Department of Psychology, University of Alberta, Edmonton, Canada Key Words tionships among species, but there is a tendency for spe- Birds W Wulst W Nidopallium W Brainstem W Cerebellum W cies within an order to clump together. There may also Evolution W Prey capture W Cognition be a weak relationship between cerebrotype and devel- opmental differences, but two of the main clusters con- tained species with both altricial and precocial develop- Abstract mental patterns. As a whole, the groupings do agree Multivariate analyses of brain composition in mammals, with behavioral and ecological similarities among spe- amphibians and fish have revealed the evolution of ‘cer- cies. Most notably, species that share similarities in loco- ebrotypes’ that reflect specific niches and/or clades. motor behavior, mode of prey capture or cognitive abili- Here, we present the first demonstration of similar cere- ty are clustered together. The relationship between cere- brotypes in birds. Using principal component analysis brotype and behavior/ecology in birds suggests that and hierarchical clustering methods to analyze a data set future comparative studies of brain-behavior relation- of 67 species, we demonstrate that five main cerebro- ships will benefit from adopting a multivariate ap- types can be recognized. One type is dominated by galli- proach. forms and pigeons, among other species, that all share Copyright © 2005 S.
    [Show full text]
  • Ultimate Papua New Guinea Ii
    The fantastic Forest Bittern showed memorably well at Varirata during this tour! (JM) ULTIMATE PAPUA NEW GUINEA II 25 AUGUST – 11 / 15 SEPTEMBER 2019 LEADER: JULIEN MAZENAUER Our second Ultimate Papua New Guinea tour in 2019, including New Britain, was an immense success and provided us with fantastic sightings throughout. A total of 19 Birds-of-paradise (BoPs), one of the most striking and extraordinairy bird families in the world, were seen. The most amazing one must have been the male Blue BoP, admired through the scope near Kumul lodge. A few females were seen previously at Rondon Ridge, but this male was just too much. Several males King-of-Saxony BoP – seen displaying – ranked high in our most memorable moments of the tour, especially walk-away views of a male obtained at Rondon Ridge. Along the Ketu River, we were able to observe the full display and mating of another cosmis species, Twelve-wired BoP. Despite the closing of Ambua, we obtained good views of a calling male Black Sicklebill, sighted along a new road close to Tabubil. Brown Sicklebill males were seen even better and for as long as we wanted, uttering their machine-gun like calls through the forest. The adult male Stephanie’s Astrapia at Rondon Ridge will never be forgotten, showing his incredible glossy green head colours. At Kumul, Ribbon-tailed Astrapia, one of the most striking BoP, amazed us down to a few meters thanks to a feeder especially created for birdwatchers. Additionally, great views of the small and incredible King BoP delighted us near Kiunga, as well as males Magnificent BoPs below Kumul.
    [Show full text]
  • 14 References
    14 REFERENCES Afik, D. and Ward, D. ( 1989). Incubation of dead eggs. Auk. 106 : 726 - 728. Ali. S. (1943). The Birds of Mysore. J. Bombay nat. Hist. Soc. 44: 206-220 . ...................... (1953). The Keoladeo Ghana of Bharatpur (Rajasthan). J. Bombay nat. Hist Soc., 51 : 531 - 536 . ..................... (2002). The book of Indian Birds. Bombay Natural History Society. Oxform University Press. Ali S. & Ripley, S.D. (1968). Handbook of the birds of India and Pakistan vol. 1 Bombay : Oxford University Press. Altmann, J. ( 1974) . ObseNational study of behaviour : sampling methods. Behaviour, 49: 227-267. Anderson, D. W. and Keith, J. 0. (1980). The human influence on seabird nesting success . Conservation implications. Bioi. Conserv.. 18 : 65- 80. Anderson, D. W. (1988). Dose-response relationship between human disturbance and brown pelican breeding success. Wild/. Soc. Bull., 16: 339-45. Baker, E.C.S. (1922-1929). Fauna of British India, Birds (2nd ed.). Voi.I-VI. Taylor and Francis, London . ......................... (1935). The indification of birds of the Indian Empire Vol. 4. Taylor and Francis. London. Baker, R.H. ( 1940). Crow predation on heron nesting colonies. Wilson Bull., 52: 124- 125. Barrows, W. B. (1912). Michigan Bird Life, pp. 146- 147. 105 Birkhead, T. R. (1977). The effect of habitat and density on breeding success tr1e common guillemot (Uria aa/ge). J. Anim. Ecol.. 46: 751-764. Blanford, W. T. (1895-1898): Fauna of British India, Birds Vols. 3 and 4. London. Boekelheide, R. J. and Ainley, D. J. (1989). Age, resource availability and breeding effort in Brandts' cormorant. Auk, 106: 389-401. Bongiorno, S. F.
    [Show full text]
  • Reproductive Success, Growth and Survival of Black-Crowned Night-Heron (Nycticorax Nycticorax) and Snowy Egret (Egretta Thula) Chicks in Coastal Virginia
    The Auk 113(1):119-130, 1996 REPRODUCTIVE SUCCESS, GROWTH AND SURVIVAL OF BLACK-CROWNED NIGHT-HERON (NYCTICORAX NYCTICORAX) AND SNOWY EGRET (EGRETTA THULA) CHICKS IN COASTAL VIRGINIA R. MICHAEL ERWIN, JOHN G. HAIG, DANIEL B. $TOTTS,AND JEFF$. HATFIELD NationalBiological Service, Patuxent Environmental Science Center, 11410American Holly Drive, Laurel,Maryland 20708, USA ABSTRACT.--Westudied reproductive success, growth, and survivalof Black-crownedNight- Heron (Nycticoraxnycticorax) and Snowy Egret (Egrettathula) chicksin two mixed-species heronries on marsh islands in ChincoteagueBay, AccomackCounty, Virginia in 1992 and 1993. We attachedradio transmitterswith mortality sensorsto the oldest chicks (A-chicks) in 11 to 22 nestsof both speciesto monitor survival during the mid- to late nestlingperiod and into the postnestingdispersal period. For both species,we found significantdifferences between 1992and 1993in growth ratesand survival. Massgrowth ratesof chickswere higher in 1993 than in 1992for both species.Culmen-length growth ratesvaried significantlydue to year-colonyeffects for night-herons,but only for hatching order for egrets.Differences in survival rates due to hatching order were found for the egrets in both years, but were found only in 1992for night-herons.As with massgrowth rates, survival of chickswas higher in 1993 than 1992.Survival of radio-markedA-chicks did not differ between speciesor years for the period from hatchingto fledging or from fledging through the end of the study (ca. two monthspostfledging). Survival ranged from 0.80 to 1.00from the time radio transmitters were attached(ca. two weeksof age) until dispersalage (53-55 daysfor egrets;55-60 days for night-herons).After birds left the colony,survival rateswere lower during the next 40 to 55 days,ranging from 0.25 to 0.60.
    [Show full text]