{"id":{"repo_id":"cape-town","oai_identifier":"oai:open.uct.ac.za:11427/12975"},"canonical_url":"https://search.dev.ndltd.org/etd/cape-town/oai:open.uct.ac.za:11427/12975","repository":{"repo_id":"cape-town","name":"University of Cape Town","base_url":"https://open.uct.ac.za/oai/request"},"display":{"title":"Investigating the possible change in breeding strategy of African black oystercatchers","abstract":"African Black Oystercatchers (Haematopus moquini) have a modal clutch size of two eggs but occasionally lay one or three eggs. It has been noted that an increase in frequency of larger threeand even four-egg clutches has occurred over the last few decades. By analysing extensive historical nest records dating back five decades I verified the occurrence of this increase in three-egg clutches over many of the sites within their breeding range. As African Black Oystercatchers are very territorial, co-operative polygyny was rejected as a sole cause (through observations). As eggs were found to be significantly similar (through intra-clutch egg shape comparisons) within clutches egg-dumping as a cause was also rejected. It was thus established that the increase in three-egg clutch frequency was indicating an increase in breeding effort. On further analysis of this increase, it was discovered that three-egg clutches offer no benefit to species fitness or breeding success as they do not result in an increased fledgling output to those of the smaller two-egg clutches. This is primarily due to inefficient incubation as a result of the extra egg, and the inability to maintain and feed a larger brood size. This study validates previous assertions that three-egg clutch frequency is increasing for African Black Oystercatchers.","abstract_html":"African Black Oystercatchers (Haematopus moquini) have a modal clutch size of two eggs but occasionally lay one or three eggs. It has been noted that an increase in frequency of larger threeand even four-egg clutches has occurred over the last few decades. By analysing extensive historical nest records dating back five decades I verified the occurrence of this increase in three-egg clutches over many of the sites within their breeding range. As African Black Oystercatchers are very territorial, co-operative polygyny was rejected as a sole cause (through observations). As eggs were found to be significantly similar (through intra-clutch egg shape comparisons) within clutches egg-dumping as a cause was also rejected. It was thus established that the increase in three-egg clutch frequency was indicating an increase in breeding effort. On further analysis of this increase, it was discovered that three-egg clutches offer no benefit to species fitness or breeding success as they do not result in an increased fledgling output to those of the smaller two-egg clutches. This is primarily due to inefficient incubation as a result of the extra egg, and the inability to maintain and feed a larger brood size. This study validates previous assertions that three-egg clutch frequency is increasing for African Black Oystercatchers.","abstract_has_math":false,"creators":["Paijmans, Dane Matthew"],"institution":"Department of Biological Sciences","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Ryan, Peter G","Hockey, Phil A R"],"committee_chairs":[],"committee_members":[],"year":2014,"date_issued":"2014","date_published":"2014","updated_at":"2026-07-22T22:23:39Z","subjects":[],"languages":["eng"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/11427/12975","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Ryan, Peter G","Hockey, Phil A R"]},{"key":"dc:creator","label":"Author","values":["Paijmans, Dane Matthew"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2015-05-28T07:02:09Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2015-05-28T07:02:09Z"]},{"key":"dc:date.issued","label":"Date","values":["2014"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Department of Biological Sciences"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["University of Cape Town"]},{"key":"dc:type","label":"Dc Type","values":["Master Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["Masters"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["MSc"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["eng"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/11427/12975"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Includes bibliographical references."]},{"key":"dc:description.abstract","label":"Abstract","values":["African Black Oystercatchers (Haematopus moquini) have a modal clutch size of two eggs but occasionally lay one or three eggs. It has been noted that an increase in frequency of larger threeand even four-egg clutches has occurred over the last few decades. By analysing extensive historical nest records dating back five decades I verified the occurrence of this increase in three-egg clutches over many of the sites within their breeding range. As African Black Oystercatchers are very territorial, co-operative polygyny was rejected as a sole cause (through observations). As eggs were found to be significantly similar (through intra-clutch egg shape comparisons) within clutches egg-dumping as a cause was also rejected. It was thus established that the increase in three-egg clutch frequency was indicating an increase in breeding effort. On further analysis of this increase, it was discovered that three-egg clutches offer no benefit to species fitness or breeding success as they do not result in an increased fledgling output to those of the smaller two-egg clutches. This is primarily due to inefficient incubation as a result of the extra egg, and the inability to maintain and feed a larger brood size. This study validates previous assertions that three-egg clutch frequency is increasing for African Black Oystercatchers."]},{"key":"dc:title","label":"Title","values":["Investigating the possible change in breeding strategy of African black oystercatchers"]}]}],"canonical_facts":{"dc:contributor.advisor":["Ryan, Peter G","Hockey, Phil A R"],"dc:creator":["Paijmans, Dane Matthew"],"dc:date.accessioned":["2015-05-28T07:02:09Z"],"dc:date.available":["2015-05-28T07:02:09Z"],"dc:date.issued":["2014"],"dc:description":["Includes bibliographical references."],"dc:description.abstract":["African Black Oystercatchers (Haematopus moquini) have a modal clutch size of two eggs but occasionally lay one or three eggs. It has been noted that an increase in frequency of larger threeand even four-egg clutches has occurred over the last few decades. By analysing extensive historical nest records dating back five decades I verified the occurrence of this increase in three-egg clutches over many of the sites within their breeding range. As African Black Oystercatchers are very territorial, co-operative polygyny was rejected as a sole cause (through observations). As eggs were found to be significantly similar (through intra-clutch egg shape comparisons) within clutches egg-dumping as a cause was also rejected. It was thus established that the increase in three-egg clutch frequency was indicating an increase in breeding effort. On further analysis of this increase, it was discovered that three-egg clutches offer no benefit to species fitness or breeding success as they do not result in an increased fledgling output to those of the smaller two-egg clutches. This is primarily due to inefficient incubation as a result of the extra egg, and the inability to maintain and feed a larger brood size. This study validates previous assertions that three-egg clutch frequency is increasing for African Black Oystercatchers."],"dc:identifier.uri":["http://hdl.handle.net/11427/12975"],"dc:language.iso":["eng"],"dc:publisher.department":["Department of Biological Sciences"],"dc:publisher.institution":["University of Cape Town"],"dc:title":["Investigating the possible change in breeding strategy of African black oystercatchers"],"dc:type":["Master Thesis"],"dc:type.qualificationlevel":["Masters"],"dc:type.qualificationname":["MSc"]},"updated_at":"2026-07-22T22:23:39Z"}