Afrotropical Bird Biology: Journal of the Natural History of African Birds最新文献

{"title":"Breeding biology of two sympatric Nesospiza finches at Nightingale Island, Tristan da Cunha","authors":"B. Dilley","doi":"10.15641/ABB.V1I.1084","DOIUrl":"https://doi.org/10.15641/ABB.V1I.1084","url":null,"abstract":"Nesospiza finches are a classic example of a simple adaptive radiation, with two ecologically distinct forms confined to the Tristan da Cunha Archipelago, South Atlantic Ocean: an abundant, small-billed dietary generalist, and a scarce, large-billed specialist. These have segregated into two species at Nightingale Island, but there is still local introgression between the two forms at Inaccessible Island. We describe the phenology and breeding behaviour of the two sympatric species at Nightingale Island (2.6 km2): Wilkins’s Finch Nesospiza wilkinsi (Endangered) and Nightingale Island Finch N. questi (Vulnerable). The finch breeding season starts in late October-November but the onset of breeding varies by 4–5 weeks among years. The small-billed Nightingale Island Finch typically (two of three study seasons) starts breeding 1–3 weeks earlier than the large-billed Wilkins’s Finch, unlike at Inaccessible Island where the Wilkins’s Finches start breeding first. Laying of initial clutches was quite well synchronised, peaking 1–2 weeks after the first nests were found. Females constructed the nests, which were mostly (>90%) in dense Spartina arundinacea tussock grass stands and occasionally in ferns or sedge grasses. Clutches comprised one or two eggs, with no difference between Wilkins’s (1.66 ± 0.48) or Nightingale Island finch clutches (1.71 ± 0.46). Incubation periods averaged longer for Wilkins’s Finch (18.3 ± 0.5 d) than Nightingale Island Finch (17.7 ± 0.5 d), but this difference was not statistically significant. Females incubated the eggs, and were fed by the males. The difference in egg volume within two-egg clutches was 2–13% for Wilkins’s Finches (mean 5.9 ± 3.3%) and 1–19% for Nightingale Island Finches (mean 8.4 ± 5.3%). At least 31% of pairs re -laid after their first breeding attempt failed but there was no evidence of double brooding. Repeat nests were 0–20 m (mean 5.6 ± 4.9 m) from the initial nest site and inter-seasonal nest sites for 38 known pairs were 0–33 m apart (mean 12 ± 9 m). No inter-species pairs or hybrid birds were seen, but two instances of inter-species fledgling provisioning were observed.","PeriodicalId":201369,"journal":{"name":"Afrotropical Bird Biology: Journal of the Natural History of African Birds","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134245167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Vocalizations of European Honey Buzzards (Pernis apivorus) in Southern Africa","authors":"A. Branfield","doi":"10.15641/abb.v1i.1068","DOIUrl":"https://doi.org/10.15641/abb.v1i.1068","url":null,"abstract":"Contrary to some sources, the European Honey Buzzard is not silent in Africa. This study documents 51 records of the species vocalizing on the continent. Vocalizations were given by birds apparently encountered alone (n=30) and when accompanied by another European Honey Buzzard (n=22). Where age was known, 11 calling birds were adults and ten were juveniles. Where details were available, most calls were given by birds in flight (n=30), with 11 from perched birds and two from birds heard calling while both in flight and perched. In most cases the sex of the bird was not recorded (n=42) and young birds (first- and second-years) are difficult to sex with certainty; of the remainder, two were males and nine were females. Most calls were the typical flight call of the species (n=43), with apparent alarm calls (n=7) the next most frequent call type. Most calls were delivered in flight (n=31), 19 by single birds and 12 by two birds together in flight. The calling by two birds was associated with flight displays similar to those described on the breeding grounds and occurred especially in late summer (December onwards; 25/40 records). A relatively high proportion of calls occurred during interactions between two European Honey Buzzards (n=18). Calling associated with two birds together and accompanied by aerial displays has not been described in Africa before, and is suggestive of either early pairing of the adult birds prior to migration or breeding activity locally in Africa. Vocalizations between young birds though may be more social as opposed to sexual in nature. The large (5X) increase in records of European Honey Buzzards in South Africa in recent years likely increases the chances of conspecific interaction. It also raises the possibility of breeding, especially in more-temperate South Africa.","PeriodicalId":201369,"journal":{"name":"Afrotropical Bird Biology: Journal of the Natural History of African Birds","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123626022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}