高山兀鹫繁殖期交配及筑巢行为初步观察

高山兀鹫(Gyps himalayensis)在海拔2 400~4 800 m的悬崖峭壁之上营巢,行为观测难度较大,资料匮缺。2013年至2015年,在天山采用样线调查法、问卷调查法,寻找到上百个巢穴。通过布设红外自动相机的方法,对高山兀鹫繁殖期巢内行为进行拍摄,同时结合焦点动物取样法和瞬时扫描法,对其交配及巢内行为进行观察和研究。共拍摄11万张照片,选出有效照片2 150张。对繁殖期行为进行了描述和定义,共7大类16种行为。根据照片逐一对比每种行为,统计各种行为拍摄张数及所占比例,其中,交配135张(6.3%),筑巢403张(18.7%),休息420张(19.5%),警戒375张(17.4%),保养335张(15.6%),运动200张(9.3%),其他282张(13.1%)。照片记录显示,交配行为从1月16日持续到3月2日,在一天的8:00~16:00时间段内,除9:00~10:00时没有记录到交配行为外,其余时间段内都有发生。交配行为次数(张数)在13:00~14:00时达到高峰,与气温同期达到高峰。交配过程持续8~15 s。筑巢期间,巢材由雌雄兀鹫运输,雌性负责将巢材放入巢中,整理、铺垫和修缮。筑巢行为在白天有三个高峰期,分别为11:00~12:00时、13:00~14:00时和15:00~16:00时。在每个高峰期后,往往出现一个短暂的低谷期。冬季食物短缺,照片显示雕鸮(Bubo bubo)、雪豹(Uncia uncia)等食肉动物进入巢内,对兀鹫繁殖造成干扰,甚至中断繁殖。作为高原健康指示物种,高山兀鹫生存状况不容乐观,急需加强保护。     

Factors affecting population regulation of a colonial vulture

Two hypotheses have been proposed to link population regulation to density‐dependent changes in demographical parameters: the habitat heterogeneity hypothesis (HHH) states that, as population density rises, an increasing proportion of individuals are forced to occupy low‐quality territories, which provokes a decline in average per‐capita survival and/or productivity although some individuals show no decline in fecundity; and the individual adjustment hypothesis (IAH), which suggests that increased densities lead to reductions in survival and/or fecundity by enhancing agonistic interactions, which affect all individuals to a similar extent. However, density‐dependent effects can be affected by density‐independent factors (DIF), such as weather. We test the effects of density dependence on annual reproductive success in Griffon Vultures Gyps fulvus at four spatial scales, nest‐site, cliff, colony and metacolony, in northern Spain from 2008 to 2015. Our results showed most support for the HHH at all scales. At the colony and cliff scale, IAH and DIF had similar importance, whereas there was little evidence of IAH at the metacolony and the nest scale. The best protected eyries (caves, potholes and sheltered ledges) produced the most fledglings and were used preferentially, whereas low‐quality eyries (exposed ledges or open crevices) were used only when the number of breeders increased. The significant interaction between breeding failure and density found for the more exposed eyries suggests that at higher densities, breeding pairs are forced to use poorer nesting areas, and the negative effect of density at the cliff scale could be due to the combined effect of a higher proportion of pairs using low‐quality eyries and the negative effect of rainfall.     

Impact of human activities on the reproduction of Hooded Vultures Necrosyrtes monachus in Burkina Faso

During the last decades, the critically endangered Hooded Vulture Necrosyrtes monachus has strongly declined across its African range. Although direct persecution has been suggested as a major cause of this decline, little is known about the impact of humans on reproductive output in West Africa. We studied the impact of human activities on the reproductive output of Hooded Vultures in the Garango area of Burkina Faso. Twenty and 56 nesting attempts were monitored, respectively, during the breeding season in 2013/14 and 2014/15, to determine reproductive success and identify causes of nest failure. Annual breeding success varied between 0.68 and 0.71 chicks fledged per breeding pair per year and productivity was assessed at 0.57 chicks fledged per territorial pair in 2014/15. The main threats imposed by humans were poaching of eggs, chicks and collection of nest materials, leading to 20% (13 out of 64 breeding attempts) of nest failures over the two years. An additional important reason for nest failure was the pruning and (partial) cutting of nest trees. Despite this high level of human interference, we found that Hooded Vulture nest success increased with proximity to human settlements, probably because breeding vultures benefit from protection by people against persecution and disturbance.     

Reduced genetic diversity in Bearded Vultures Gypaetus barbatus in Southern Africa

The Bearded Vulture Gypaetus barbatus occurs throughout its range in small and dwindling population fragments with limited genetic differentiation between populations, suggesting that the species might be managed as a single entity. The numbers of East and Southern African Bearded Vultures included in previous studies were small, so we determine the genetic variation within, evolutionary placement of and connectivity among sub‐Saharan African populations. Mitochondrial DNA fragment analyses detected little or no differentiation between populations in Ethiopia and Southern Africa, with reduced haplotype diversity in Southern Africa compared with populations in the Northern Hemisphere. The results inform conservation management of this species globally and locally, and offer guidelines for translocations should populations continue to decline.     

A solar-powered transmitting video camera for monitoring cliff-nesting raptors

ABSTRACT.   We designed a system of solar-powered video cameras that transmitted images via telemetry to a monitor. This system allowed us to study the breeding behavior of the Bearded Vulture ( Gypaetus barbatus ) in the Pyrenees (northeastern Spain). From 2000 to 2004, 12 nests in seven territories were equipped with video cameras. To avoid disturbing the birds, equipment was installed 3–8 weeks before egg-laying. The acceptance rate was 75%. No decline in productivity was observed for nests monitored with video cameras compared to control nests. The cameras enabled us to document egg-laying, hatching asynchrony, the nestlings' diet, and the parents' breeding behavior from distances of 2–3 km, although technical problems temporarily interrupted the transmission of images. Video cameras can be used successfully to study the Bearded Vultures, and probably other cliff-nesting raptors, without reducing productivity.     

High occurrence of extra-pair partnerships and homosexuality in a captive Cape Vulture Gyps coprotheres colony§

The Cape Vulture Gyps coprotheres is an Endangered colonial cliff-nesting species that is typically cited as monogamous. Observations of wild Cape Vulture colonies note extra-pair breeding activities but homosexual activity has never been confirmed. Observations of breeding behaviours within a captive colony were conducted at VulPro’s breeding facilities in South Africa The captive breeding programme included 10 breeding pairs and a total of 41 non-releasable, individually recognisable, and genetically sexed subadults or adults. Observations were conducted over the 2014 breeding season as part of a study investigating the social and rearing conditions of chicks intended for release in a population supplementation programme. A high percentage of total colony copulation attempts (22%) were extra-pair copulations but only 23 interactions resulted in cloacal contact or possible sperm transfer. Four paired males formed extra-pair relationships, two of which were homosexual.     

Persistent organochlorine pesticides detected in blood and tissue samples of vultures from different localities in South Africa

Gaschromatography was used to establish the presence of quantifiable residues of 14 persistent chlorinated hydrocarbon pollutants in whole blood, clotted blood, heart, kidney, liver and muscle samples obtained from individual African whitebacked (Pseudogyps africanus), Cape griffon (Gyps coprotheres) and Lappetfaced (Torgos tracheliotos) vultures from different localities in South Africa. The levels of pesticides measured in whole blood samples of live specimens were compared between nestlings from two natural breeding colonies, adults from a wildlife area and birds held in captivity. Statistically significant (P<0.05) differences between populations were detected in geometric means calculated for γ-BHC (lindane), α(cis)-chlordane and α-endosulfan. Five of the organochlorine contaminants displayed significant variations between concentrations detected in the clotted blood, organs and muscles excised from vulture carcasses. This includes residues of γ-BHC, α-chlordane, dieldrin, β-endosulfan and heptachlor epoxide. Values of the respective biocides measured in vulture samples were generally low in comparison to results documented for a number of avian species. Although no threat is posed by any of the organochloride pesticides, continual monitoring of especially breeding colonies is recommended. Furthermore, the suitability of African whitebacked vulture nestlings as basic bioindicators is highly advocated.     

秃鹫巢内育雏期亲鸟与幼鸟行为及时间分配

2016和2017年,采用焦点动物取样法及全事件记录法,在新疆和静县巴仑台镇研究了4个繁殖巢的秃鹫(Aegypius monachus)繁殖行为。通过红外相机和人工观察,构建了秃鹫巢内育雏期的行为谱,将秃鹫亲鸟的行为划分为9类33种,将雏鸟行为划分为6类28种。结果表明,亲鸟喂食次数的最高峰出现在12:30~13:30时,随后在15:30~18:30时之间出现一个小高峰。在育雏期,亲鸟行为以护幼、观望和警戒为主,雏鸟则以休息和观望为主。将巢内育雏期分为三个阶段:育雏前期(4~5月)、育雏中期(6月)、育雏后期(7月),运用单因素方差分析(one-way ANOVA)检验不同育雏阶段亲鸟、雏鸟行为时间分配的差异。结果显示,育雏前期与后期之间亲鸟的行为时间分配差异不显著(P0.05),前期与中期和中期与后期之间,亲鸟的行为时间分配差异均显著(P0.01);育雏前期、中期与后期的雏鸟行为时间分配差异均显著(P0.01)。国内秃鹫繁殖主要面临食物短缺、人类活动干扰等威胁。     

Using Africa's protected area network to estimate the global population of a threatened and declining species: a case study of the Critically Endangered White‐headed Vulture Trigonoceps occipitalis

The White‐headed Vulture Trigonoceps occipitalis (WhV) is uncommon and largely restricted to protected areas across its range in sub‐Saharan Africa. We used the World Database on Protected Areas to identify protected areas (PAs) likely to contain White‐headed Vultures. Vulture occurrence on road transects in Southern, East, and West Africa was adjusted to nests per km² using data from areas with known numbers of nests and corresponding road transect data. Nest density was used to calculate the number of WhV nests within identified PAs and from there extrapolated to estimate the global population. Across a fragmented range, 400 PAs are estimated to contain 1893 WhV nests. Eastern Africa is estimated to contain 721 nests, Central Africa 548 nests, Southern Africa 468 nests, and West Africa 156 nests. Including immature and nonbreeding birds, and accounting for data deficient PAs, the estimated global population is 5475 ‐ 5493 birds. The identified distribution highlights are alarming: over 78% (n = 313) of identified PAs contain fewer than five nests. A further 17% (n = 68) of PAs contain 5 ‐ 20 nests and 4% (n = 14) of identified PAs are estimated to contain >20 nests. Just 1% (n = 5) of PAs are estimated to contain >40 nests; none is located in West Africa. Whilst ranging behavior of WhVs is currently unknown, 35% of PAs large enough to hold >20 nests are isolated by more than 100 km from other PAs. Spatially discrete and unpredictable mortality events such as poisoning pose major threats to small localized vulture populations and will accelerate ongoing local extinctions. Apart from reducing the threat of poisoning events, conservation actions promoting linkages between protected areas should be pursued. Identifying potential areas for assisted re‐establishment via translocation offers the potential to expand the range of this species and alleviate risk.     

Factors influencing perch selection by communally roosting Turkey Vultures

ABSTRACT Many birds roost communally during at least part of their annual cycle, suggesting that for them the advantages of living in a group outweigh the disadvantages. However, perch sites within a roost may vary in quality because of differences in degree of exposure to the elements, predators, and fecal droppings. Individuals should select perches in the roost that minimize costs while enabling them to experience the benefits of communal roosting. We studied communally roosting Turkey Vultures (Cathartes aura) in northeastern Iowa (USA) from late August to mid‐October, when hatching‐year (HY) birds had joined the roost and were distinguishable from after‐hatching‐year (AHY) birds. On 82 d during our 4‐yr study (2004–2007), we noted the age class and perch position of vultures on two communication towers used as a preroost site. Perches used by vultures were classified as top‐level (with no perches above them) or lower‐level (with other perches above them). Top‐level perches were preferred by Turkey Vultures. Of 1713 birds recorded, 71% were on top‐level perches, even though only 39% of available perches were top‐level. Vultures did not use lower perches if top perches on that tower were unoccupied. The percentage of birds using lower perches increased as the number of vultures present increased, suggesting that top‐level perches were occupied first. AHY birds used top‐level perches more often than expected and HY birds used top‐level perches less often than expected, implying that age‐related dominance affected perch selection. On 61 of 82 d (74%), top‐level perches of both towers were occupied and, on 8 d (10%), only top perches on one tower were occupied. However, on 13 d (16%), both top‐level and lower‐level perches were occupied on one tower while no vultures perched on the other tower, suggesting that social attraction to other vultures can override a general preference for top‐level perches. Thus, our results provide evidence that social attraction, age‐related dominance, and preference for higher perches are proximate factors influencing perch selection in communally roosting Turkey Vultures. Ultimate factors that may be responsible for Turkey Vultures preferring higher roosting perches are reduced risk of predation, less exposure to fecal droppings that might reduce their plumage quality, and better visual information for locating food sources.