Vigilance during Preening in Coots Fulica atra

In birds, vigilance during feeding is usually linked with (1) the many‐eyes‐hypothesis, (2) the dilution effect, and (3) the intraspecific scramble competition hypothesis. To exclude competition for resources as a driving force in vigilance research into activities other than feeding is necessary. Additionally, variables such as nearest neighbour distance and position within a flock are supposed to influence vigilance and vigilance of singletons should be compared with vigilance of flock members. I studied vigilance during preening in Eurasian Coots (Fulica atra) and counted the number of scans per minute. A total number of 117 coots were sampled with 16 of them preening alone. Coots preening alone showed a significantly higher scan rate. I found a significant negative correlation between vigilance and flock size while nearest neighbour distance correlated positively with vigilance. Further, vigilance was higher in individuals at the edge. A general linear model using nearest neighbour distance and flock size within 10 m as covariates also revealed a significant influence of flock size but not of nearest neighbour distance. The centre‐edge effect still remained significant. These results indicate that flock size is the most influential predictor of vigilance in preening coots, followed by spatial organization. However, using nearest neighbour distance instead of flock size also produced a significant model as did the flock size measurement within a radius of 20 m. As scramble competition could be ruled out, the flock size effect may be indeed related to predation.     

Disturbances by dog barking increase vigilance in coots Fulica atra

Animals frequently interrupt their activity to look up and to scan their surrounding environment for potential predators (vigilance). As vigilance and other activities are often mutually exclusive, such behaviours are at the expense of feeding, sleeping or preening. Authors of many wildlife disturbance studies found that people with free-running dogs provoked the most pronounced disturbances (e.g. greater flushing distances and more birds affected). However, dogs on leash may also negatively affect wild animals, and barking dogs may lead to an increase in vigilance. In this study, I tested this hypothesis in coots (Fulica atra) using three different playback procedures: (1) dog barks, (2) conspecific coot alarm calls and (3) chaffinch song. The trials were conducted in spring and autumn 2005 at three study sites in southwestern Germany. During the dog playbacks, vigilance increased significantly from 17 to 28%. This increase in vigilance is comparable to the presence of a natural predator. As expected, vigilance also increased significantly during conspecific coot alarm calls but not during playbacks of the chaffinch song control. Two main findings result from the study: (1) coots respond to acoustic traits of dogs and may be able to acoustically recognise this predator and (2) this increase in vigilance might have implications for conservation, especially when considering buffer zones around sensitive areas.     

骨顶鸡等游禽对不同人为干扰方式的响应

分别于2008年4月至6月和2009 年4月至6月, 采用目标动物取样法在黑龙江省安邦河湿地和大庆龙凤湿地研究了骨顶鸡等水鸟对人为干扰的行为响应。结果表明:骨顶鸡对行人和机动车辆两种干扰的反应距离类似,但耐受程度有所不同,骨顶鸡对机动车辆干扰的耐受性要好于行人干扰。在以游客等行人干扰为主的安邦河湿地,骨顶鸡以及其他游禽对干扰产生行为反应的比例要高于以机动车辆干扰为主的龙凤湿地,说明相对于行人干扰骨顶鸡对机动车辆更容易耐受;在安邦河湿地,骨顶鸡对划船的反应距离以及反应程度要大于人行走,说明骨顶鸡对于侵入性的干扰更为敏感。此外,对凤头(Podiceps cristatus)、黒颈(Podiceps nigricollis)、小(Tachybaptus ruficollis)、黑水鸡(Gallinula chloropus)、红头潜鸭(Aythya ferina)、赤膀鸭(Anas strepera)、绿头鸭(Anas platyrhynchos)、斑嘴鸭(Anas poecilorhyncha)、绿翅鸭(Anas crecca)、白眉鸭(Anas querquedula)、赤颈鸭(Anas penelope)、琵嘴鸭(Anas clypeata)等游禽对人为干扰的反应距离、耐受距离以及遭受干扰时的反应比例进行了研究,结果显示3种对干扰的耐受距离差异不显著,12种鸭类中红头潜鸭对人为干扰的敏感性要小于其他鸭类,斑嘴鸭和绿头鸭则相对敏感。     

白骨顶雏鸟叫声回放实验

2008年4～6月在黑龙江省安邦河湿地自然保护区录制白骨顶(Fulica atra)雏鸟叫声后回放,分析回放时环境中的背景噪音对繁殖期白骨顶活动的影响.结果表明,游人、拖拉机产生的噪音及过往车辆均会干扰繁殖期白骨顶的正常活动.     

骨顶鸡的繁殖行为

2008和2009年4-9月,对黑龙江省安邦河自然保护区以及龙凤湿地骨顶鸡繁殖种群进行了观察.结果表明:骨顶鸡繁殖季节会建造3种巢结构:炫耀台、产卵巢和育雏巢,雌雄共同参与筑巢及领域防卫活动;巢高和巢深随窝卵数增多而呈上升趋势;平均窝卵数为8.77±0.24(n=75)枚,窝卵数随繁殖时间推迟而呈减少趋势;骨顶鸡雌雄共同参与孵化,雌性平均每次孵化时间高于雄性;雌雄共同参与喂雏,雏鸟至亚体阶段才完全独立,之前需亲鸟饲喂;骨顶鸡是杂食性鸟类,食物以植物为主,但也摄取动物性食物.     

若尔盖湿地骨顶鸡的繁殖生态及适应性探讨

本文研究了四川省若尔盖湿地骨顶鸡Fulica atra的繁殖生态,讨论了骨顶鸡繁殖特征对高原的适应性。结果表明:若尔盖骨顶鸡平均筑巢期为6.73 d±0.36 d,平均巢底距水面距离平均为7.83 cm±0.64 cm,未发现对旧巢重复利用的现象;平均窝卵数5.83枚±2.15枚,平均卵质量31.90 g±0.37 g,平均孵卵时间26.64 d±2.83 d。与低海拔平原湿地相比,高寒湿地繁殖的骨顶鸡窝卵数更少、孵化期更长,并偏好在植被盖度适中、紧邻植被且草高较高的生境中营巢。主成分分析结果显示,影响研究区域骨顶鸡巢址选择的主要因子是安全因子,其次是交通因子与种内竞争因子。与平原地区繁殖的骨顶鸡相比,若尔盖地区骨顶鸡在繁殖生态特征上呈现出对安全因子高度偏好的特点,可能是其对高原多变气候环境和较高捕食压力的一种适应和选择策略。     

Capillarity and fiber types in locomotory muscles of wild common coots,Fulica atra

Six locomotory muscles of wild common coots, Fulica atra, were analyzed histochemically. Capillarity and fiber-type distributions were correlated to the functional implications and physiological needs of each muscle. Leg muscles exhibit three unevenly distributed fiber types, a pattern that reflects the great variety of terrestrial and aquatic locomotory performances that coots are able to develop. Aerobic zones are presumably recruited during steady swimming and diving, while regions with anaerobic characteristics may be used for bursts of activity such as sprint swimming or during take off, when coots run along the water's surface. Fiber types and capillarization in wing muscles have a marked oxidative trend. High wing beat frequencies, short and broad wings, and the long distance migrations that these birds perform indicate that the presence of high numbers of oxidative fibers and the well developed capillary supply are needed for enhanced oxygen uptake. The pectoralis muscle, except in its deep part, has exclusively fast oxidative fibers with a very high staining intensity for succinate dehydrogenase assay as compared to the same fiber type of other muscles. Its predominant role in flapping flight justifies these characteristics that are typical of fibers with high aerobic metabolism. The deep part of the pectoralis muscle presents a low proportion of an unusual slow anaerobic fiber type. These fibers could play a role during feeding dives when the bird presses the air out of the feathers by tightening the wings against the body. A linear relationship between capillary and fiber densities in all coot muscles studied reflects an adjustment between fiber diameter and vascularization in order to obtain the oxygen for mitochondrial supply. This strategy seems a suitable way to cope with the rigid aerobic constraints that flying and diving impose upon the coot's physiology. J. Morphol. 237:147–164, 1998. © 1998 Wiley-Liss, Inc.     

骨顶鸡等游禽对不同人为干扰的行为响应

分别于2008年4月至6月和2009年4月至6月,采用目标动物取样法在黑龙江省安邦河湿地和大庆龙凤湿地研究了骨顶鸡等水鸟对人为干扰的行为响应.结果表明:骨顶鸡对行人和机动车辆两种干扰的反应距离类似,但耐受程度有所不同,骨顶鸡对机动车辆干扰的耐受性要好于行人干扰.在以游客等行人干扰为主的安邦河湿地,骨顶鸡以及其他游禽对干扰产生行为反应的比例要高于以机动车辆干扰为主的龙凤湿地,说明相对于行人干扰骨顶鸡对机动车辆更容易耐受;在安邦河湿地,骨顶鸡对划船的反应距离以及反应程度要大于人行走,说明骨顶鸡对于侵入性的干扰更为敏感.此外,对凤头鹛鹏(Podicepscristatus)、黑颈鹏鹧(Podiceps nigricollis)、小鹏鹏(Tachybaptus ruficoUis)、黑水鸡(Gallinula chloropus)、红头潜鸭(Aythya ferina)、赤膀鸭(Anas strepera)、绿头鸭(Anas platyrhynchos)、斑嘴鸭(Anas poecilorhyneha)、绿翅鸭(Arias crecca)、白眉鸭(Anasquerquedula)、赤颈鸭(Ariaspenelope)、琵嘴鸭(Anas clypeata)等游禽对人为干扰的反应距离、耐受距离以及遭受干扰时的反应比例进行了研究,结果显示3种鹛鹧对干扰的耐受距离差异不显著,12种鸭类中红头潜鸭对人为干扰的敏感性要小于其他鸭类,斑嘴鸭和绿头鸭则相对敏感.     

Does increased habitat complexity reduce predation and competition in coral reef fish assemblages?

Greater habitat complexity is often associated with a greater abundance and diversity of organisms. High complexity habitats may reduce predation and competition, thereby allowing more individuals to occupy a given area. Using 16 spatially isolated reefs in the Bahamas, I tested whether increased habitat complexity reduced the negative effects of resident predators and competitors on recruitment and survival of a common damselfish. Two levels of habitat complexity were cross-factored with the presence or absence of two guilds of resident fishes: predators (sea basses and moray eels) and interference competitors (large territorial damselfishes). I monitored subsequent recruitment and recruit mortality for 60 days. Residents had strong negative effects on recruitment regardless of habitat complexity. In the presence of residents, recruits suffered high mortality immediately after settlement that was similar on low and high complexity reefs, although high complexity reduced mortality of recruits that survived this early postsettlement period. Comparisons between shelter hole diameters and the sizes of residents suggest that territorial damselfishes and small resident predators could access most shelter holes, whereas large resident predators were excluded from many shelter holes. This study demonstrates that whether habitat complexity reduces predation and competition may depend on several key factors, such as the availability of appropriate shelter, behavioral attributes of interactors, and developmental stage of prey/inferior competitors.     

The vigilance components of begging and sibling competition

The conflict between siblings over how parental resources are divided has promoted the evolution of specific behaviour to outcompete each other. Young animals look out for parents’ arrival in order to start begging as quickly as possible, since a rapid begging reaction increases the likelihood of being fed before nestmates. If the young can physically intercept the parents, selection might be operating on the offspring ability to monitor parent arrival (vigilance towards parents) and any sudden modifications in siblings’ behaviour (vigilance towards siblings). To investigate the adaptive value of nestling vigilance in the context of family interactions, we recorded which direction barn owl Tyto alba siblings were facing in 89 two‐chick broods before the first parental feeding visit of the night. Nestlings were more vigilant towards nest entrance than expected by chance suggesting that vigilance towards parents is an important component of sibling competition. When positioned near the nest‐box entrance where parents predictably deliver food, the younger individual (i.e. junior) looked more towards the entrance than its older sibling. Thus, when the likelihood of obtaining a food item is relatively high, juniors are more vigilant than seniors to detect the incoming parent. When positioned at the back of the nest, the senior looked relatively more frequently towards its sibling than the junior did in the same situation. This suggests that when the likelihood of obtaining a food item is relatively low, seniors are more vigilant than juniors to observe their sibling. Because vigilance was not related to hunger level and prey obtaining, we propose the hypothesis that vigilance towards parents and siblings only indirectly influences the outcome of sibling competition.     

黑龙江安邦河自然保护区白骨顶营巢及领域特征

2007年4～8月在黑龙江安邦河自然保护区调查了白骨顶的巢址、领域等繁殖特征,测定了巢和卵的量度、巢址生境因子,并用最小凸多边形法测算了白骨顶的领域.结果显示:巢多位于距离明水面较近的草丛中,2/3以上的巢址距离明水面1～5 m,巢下水深20～80 cm,巢间距离10～50 m.巢址附近的植被主要有芦苇、香蒲和藨草,2/3以上巢的植株密度在1～50株/m2之间,植株高度在51～200 cm之间.领域形状多为近似于长方形的扁多边形,面积为3000～5000 m2,领域由明水面和草丛两部分组成,二者具有不同的功能.     

Sleeping gulls monitor the vigilance behaviour of their neighbours

Individuals in groups are often thought to scan their surroundings for threats independently of one another. Models, however, suggest that foragers should monitor the vigilance level of their neighbours to prevent cheating, and to gather information about incipient predation risk. Evidence for monitoring of vigilance is scant. Here, I examined changes in vigilance levels in sleeping gulls (Larus sp.) surrounded by neighbours in various states of alertness. Controlling for group size and neighbour density, gulls interrupted sleep more often to scan their surroundings, and were therefore more vigilant, when their neighbours were alert rather than sleeping or preening. The results provide evidence for copying of vigilance within groups of birds, suggesting a complex flow of information about predation risk in groups.     

Inter-specific competitors reduce inter-gender competition in Negev Desert gerbils

We examined gender-dependent competitive interactions between two nocturnal desert gerbil species, Gerbillus andersoni allenbyi and G. pyramidum, by a field manipulation experiment. The study was done in two 1-ha enclosed plots and included allopatric (only G. a. allenbyi) and sympatric (both species together) treatments. Seed trays and thermal imaging cameras were used to observe the gerbils foraging activities and aggressive interactions. We found that the negative effect of the competitively dominant species, G. pyramidum, on time spent in seed trays, and ability to control these artificial food patches, was stronger on male than on female G. a. allenbyi. Consequently, the aggression of male G. a. allenbyi towards female G. a. allenbyi was markedly reduced, indicating that the dominant species mediated competition between the genders of the subordinate species. Furthermore, this interference-mediated indirect effect was associated with a decrease in the body mass of male G. a. allenbyi and an increase in the survival of female G. a. allenbyi. We suggest that both the reduction in intra-specific aggression and the positive effect on female survival can potentially stabilize competitive interactions and promote coexistence in this small mammal community.