河北唐海湿地四种鹭的种群动态和繁殖空间生态位

2004年8月—2005年7月对河北唐海湿地夜鹭(Nycticoraxnycticorax)、白鹭(Egtettagarzetta)、池鹭(Ardeolabacchus)、大白鹭(Casmerodiusalbus)的种群动态和繁殖行为进行了观察,并对巢群关系进行了研究。统计了4种鹭垂直和水平巢位的巢密度,计算了不同种鹭巢的生态位重叠、生态位宽度值。结果4种鹭在唐海数量最多月份为4—9月,最大量达到了近5800只。共有Ⅰ、Ⅱ两个巢区,迁来Ⅱ区时间较Ⅰ区晚半个月左右。除池鹭外,3种鹭之间均有争巢现象,后期趋于稳定。迫于密度压力和竞争,部分白鹭和池鹭取食范围较广。除大白鹭外,其他3种鹭同种间均有混交现象。在混巢区,夜鹭迁来最早,数量最大,为优势种,多数占据中心区的顶巢;大白鹭数量最少,亦占据中心区的顶巢;白鹭迁来较晚,占据中位巢;池鹭迁来最晚,数量较白鹭少,多数在边缘区单独筑巢,少数在中心区占下位巢。白鹭巢的垂直生态位最宽;夜鹭巢的水平生态位最宽;池鹭巢的综合空间生态位最宽。池鹭和夜鹭巢位的空间格局最为相似,池鹭和白鹭的生态位重叠较大。夜鹭的数量最多、大白鹭的个体最大,导致其处于优势;白鹭和池鹭数量少、个体小,导致其处于劣势。唐海湿地内丰富的食物和适宜的林带是鹭鸟密度较大的主要原因。此外,鹭类只筑巢在散布的、双行杨树林带均高为22m以上区域,是该地鹭类巢区的主要特点。     

绿鹭的繁殖习性观察

2001年4－9月在合肥市对绿鹭（Butorides striatus)的繁殖习性进行了观察。绿鹭营巢生境主要选择在建筑物附近的高大阔叶树上,常一树一巢,未见与其他鹭类混群营巢。每巢产3－5枚卵,孵卵期21d,育雏期41d,42日龄后幼鸟离巢飞走,出飞存活率62．5％。育雏期雏鸟主要食物为小型鱼类。在4所大学校园及1处公园统计到有效巢56个,推算绿鹭224只。绿鹭在合肥繁殖属首次记录。     

Breeding success of a colony of Boat-billed Herons Cochlearius cochlearius (Ciconiiformes: Ardeidae) in pasturelands of Costa Rica

The breeding success of a double-brooding colony of Boat-billed Herons Cochlearius cochlearius was studied in pasturelands of Costa Rica. Mean clutch size in the first clutches (2.9 eggs/nest) was higher than in second and repeat clutches (2.3 eggs/nest). Breeding success was similar in the first attempt and second attempts (20.7% and 21.7%, respectively). In both attempts earlier nests enjoyed a higher breeding success. Starvation of the youngest chicks within the nest and destruction of nests by bad weather conditions were the main factors related to nestling death. No effects of human activity on the reproduction of the breeding colony were observed.     

Reproductive tactics of the ringed plover Charadrius hiaticula

Reproductive tactics of ringed plovers Charadrius hiaticula were studied at three localities in SW Sweden during five seasons. The usual clutch size is four, but removal experiments showed that females can produce five eggs in succession, with similar intervals between all eggs. High predation made mean breeding success per clutch low, 6.3% of eggs resulting in fledged young. Replacement clutches were common, and many pairs laid again after rearing their first brood to fledging. Egg laying spanned three months, much longer than for other waders in this region. Between years, reproductive success varied unpredictably with time of the season, but averaged over several years, the expected success was low and similar for the different parts of the breeding season. Chicks from late clutches had similar survival and recruitment as others. Because of the long breeding season and high rate of nest failure a female may produce up to five clutches of four eggs per season, containing in total about 3.7 times her own mass. Yearly local survival of adult females and males was estimated to 84.6 and 88.6%, respectively. Ability to produce many clutches with similar expected success throughout the season favours a long reproductive period, sometimes leading to double-brooding. Possible life-history trade-offs are discussed.     

Blue penguin (Eudyptula minor) nest distribution and breeding success on Otago Peninsula, 1992 to 1998

Abstract

Annual counts of nests with eggs or chicks (known nests) were made at blue penguin (Eudyptula minor) breeding sites on the Otago Peninsula in each November from 1994 to 1997. Although the population has doubled to an estimated 600 known nests over this period, the number of breeding sites on the Otago Peninsula has reduced since the 1970s. Breeding success at three areas at Taiaroa Head were monitored by regular nest checks in the breeding season from 1992 to 1998. At Taiaroa Head reproductive success ranged from 41 to 78% at the three sites during the seven‐year study and was generally higher for pairs nesting in nest boxes than for those in burrows. The percentage of breeding pairs that laid a second clutch after fledging at least one chick from their first clutch (double brooded) varied between seasons (0–48%) and was correlated with the date of the onset of breeding. Egg loss, possibly through predation by Norway rats (Rattus norvegicus), influenced the significantly lower reproductive success at one area (Area A) at Taiaroa Head during the 1996 season.     

Nest monitoring does not affect nesting success of Whinchats Saxicola rubetra

It is important to assess the effect that research activities may have on animals in the wild, especially when key parameters, such as breeding success, could potentially be influenced by observer activity. For birds, some studies have suggested that nest monitoring can increase the chances of nest failure due to predation, whereas others suggest that human nest visits may actually deter mammalian predators. Nest monitoring visits can also influence breeding success more indirectly by altering parental provisioning behaviour. Here, the influence of monitoring activities on nest success was examined in a ground‐nesting grassland bird, the Whinchat Saxicola rubetra. During the egg phase, a sample of nests were not visited between the initial finding event and the estimated hatching date; instead, the nest status was assessed at a distance. Daily survival rates (DSR) for these nests were compared with that of nests visited every 2 days. During the nestling phase, the effects of observer nest visits on parental provisioning behaviour were determined. Nest visits were found not to affect egg DSR significantly, and parental provisioning was disrupted for a maximum of 20 min (0.52% of the nestling period) following an observer visit. Given the variation in response to nest visits across species, we suggest that consideration should be given to observer impact in all studies where predation risk is high. Here, we illustrate a method for researchers to assess the impact of their nest visits to ensure they are not biasing estimates of breeding success.     

Nest survival is influenced by parental behaviour and heterospecifics in a mixed‐species colony

Studies of avian nest success often focus on examining influences of variation in environmental and seasonal factors. However, in‐depth evaluations can also incorporate variation in individual incubation behaviour to further advance our understanding of avian reproductive ecology. We examined these relationships in colonially nesting Black‐crowned Night‐Herons Nycticorax nycticorax using intensive video‐monitoring methods to quantify incubation behaviours. We modelled nest survival as a function of both extrinsic factors and incubation behaviours over a 3‐year period (2010–12) on Alcatraz Island, USA. Model‐averaged parameter estimates indicated that nest survival increased as a function of greater incubation constancy (% of time spent incubating eggs within a 24‐h period), and average daily precipitation throughout the nesting stage. Common Ravens Corvus corax are the only known nest predator of Night‐Herons on Alcatraz Island, as on many other coastal Pacific islands. We also investigated the effects of heterospecific nesting of California Gulls Larus californicus and Western Gulls Larus occidentalis in a mixed‐species colony with Night‐Herons, based on nesting proximity data collected over a 2‐year period (2011–12). This second analysis indicated that, in addition to incubation behaviours, nesting heterospecifics are an important factor for explaining variation in Night‐Heron nest survival. However, contrary to our original expectation, we found that Night‐Herons experienced increased nest survival with increasing distance from gull colony boundaries. These results may apply to other areas with multiple colonial nesting species and similar predator communities and climatic patterns.     

Distribution pattern of an expanding Osprey ( Pandion haliaetus) population in a changing environment

We studied the nest site selection and distribution pattern at landscape level of the German Osprey population, and demonstrated how to test the predictions of the ideal free distribution theory and its derivatives on such an expanding population. Information about the location and breeding success of each Osprey nest site between 1995 and 2005 was collected through a long-term monitoring programme. Data of land cover types were acquired from the administrations of each federal state and the CORINE Land Cover database. The results showed that Ospreys preferred landscapes with more water bodies and forests. Such sites were also occupied earlier and had higher local population density. However, in the study period of 11 years, there was a gradual shift from forest-dominated landscapes to agricultural land-dominated landscapes. The breeding success increased over time, with no difference in the breeding success between pairs nesting on trees and poles, whereas there was higher breeding success at nest sites surrounded by more agricultural land and less forest. The more efficient foraging in eutrophic lakes in agricultural landscapes was the most likely cause for the higher breeding success. The distribution pattern of the Ospreys did not match the resource allocation, which deviated from the models tested. We suggested that the proximate cues used for nest site selection mismatched site quality due to anthropogenic environmental changes.     

Increased hunting effort buffers against vole scarcity in an urban Kestrel Falco tinnunculus population

Capsule In years with low vole abundance birds visited hunting grounds more frequently and for longer.

Aims To describe diet composition, hunting behaviour, habitat choice and reproductive success of urban Kestrels during changing vole abundance.

Methods For five years, we studied the hunting effort of Kestrels in a medium-sized city during the breeding season. Pitfall traps were used for determining vole abundance. Kestrel diet composition was determined from pellet analyses. The number of eggs and offspring was recorded during at least two consecutive visits for each nest and each breeding stage.

Results In contrast to larger European cities, the Common Vole Microtus arvalis was a key part of the Kestrels' diet and did not fluctuate significantly according to vole availability. Reproductive success was quite high and stable throughout years with different vole abundance. In years of low vole abundance, the arrival frequency at hunting grounds and time spent there increased. During years with a low vole population, Kestrels had less hunting success and the rate of successful visits decreased. Therefore, Kestrels probably had to change hunting grounds more frequently. During low vole years Kestrels used less demanding techniques, e.g. perching, despite the lower success of these hunting techniques, to avoid extremely high energetic costs.

Conclusions An increase in hunting helps to maintain a proper diet and consequently reproductive success. Vole abundance did not change dramatically during the study period, as reported by studies from western and northern Europe. The proportion of ruderal habitats on the city periphery is higher than in more monotonous farmland habitats. Ruderal habitats can be important when Kestrels look for mammals other than voles, especially during vole scarcity.     

Light data from geolocation reveal patterns of nest visit frequency and suitable conditions for efficient nest site monitoring in Common Swifts Apus apus

ABSTRACT

Capsule: We developed a protocol for efficient monitoring of potential Common Swift Apus apus nest sites which considers variation in nest visit frequency across the breeding season and in relation to time of day and weather.

Aims: To investigate patterns of nest visit frequency in Common Swifts in order to improve the efficiency and reliability of the monitoring of nest sites threatened by building renovations.

Methods: We derived information on nest attendance from light data recorded by geolocators from ten adult Common Swifts during three breeding seasons (n?=?686 individual sampling days) and analysed how nest visit frequency varied across the breeding season and in relation to time of day and weather.

Results: The mean nest visit frequency was 5.63 visits per bird per day (0.32 visits per hour of daylight). The daily number of visits was highest at the beginning of July during chick-rearing. Moreover, it was positively correlated with temperature and negatively correlated with rainfall and wind speed. Nest visit frequency showed a distinct peak around sunset, while also being relatively high in the morning and around noon.

Conclusion: We recommend monitoring potential Common Swift nest sites in Central Europe between the end of June and mid-July during good weather between 0.50 and 7.75?h after sunrise or between 3.00?h before sunset and sunset, when observation bouts of 0.5–2.0?h provide an encounter probability greater than 90%. Our study shows that repurposing geolocator light data – usually used to study bird migration – for investigating nest attendance in cavity-breeding birds can provide important information for bird conservation.     

Sex roles, parental experience and reproductive success of eastern kingbirds, Tyrannus tyrannus

We quantified parental behaviour of eastern kingbirds during the incubation and nestling periods to determine parental roles, and to examine the impact of previous breeding experience (defined as having bred on the territory in the past) on behaviour and reproductive success. Females performed all incubation, while males spent more than 60% of their time in vigilant or nest guarding behaviour during incubation. Parental roles were not defined as sharply during the nestling period. Females spent more time vigilant, but males provisioned young at only 54% of the rate of females. Vigilance and nest watching were still primarily male duties. Male and female behaviour did not vary with the pair's combination of experience (e.g. experienced-experienced versus inexperienced-inexperienced in previous-current breeding season, respectively) during either phase of reproduction, but experienced males were more vigilant during incubation and fed young relatively more than inexperienced males. Experienced females were also more efficient foragers. Although behaviour did not differ among the four combinations of pair experience, inexperienced pairs none the less lost the most young to starvation and predation. Consequently, inexperienced pairs fledged one less nestling per nesting attempt than did pairs with at least one experienced breeder. Our results suggest that having at least one experienced breeder substantially improved a pair's reproductive success. We propose that female site fidelity is a safeguard to avoid the lower breeding success a female would incur if she were to move to a new territory and breed with an inexperienced male. Copyright 1999 The Association for the Study of Animal Behaviour.     

Assessment of territory quality and its effects on breeding success in a migrant passerine, the Wheatear Oenanthe oenanthe

This paper examines how a returning migrant assesses the quality of an area as a breeding territory before the period of peak food demand and how effective the assessment is in terms of breeding success. Male Wheatears Oenanthe oenanthe return from Africa to choose territories in the Breckland of eastern England about March, females arriving shortly after males. The food supply was predictable: prey densities during the breeding period (egg-laying to chick independence) were strongly correlated with prey densities at the same sites during the period of arrival and territory establishment. Prey densities were also related to vegetation structure, averaging highest on short turf. Male arrival date and territory size were not significantly related to prey density but were strongly related to vegetation structure, implying that birds used vegetation as an indirect clue to prey availability. Neither territory size nor nest spacing appeared to affect nest losses caused by predators. The major variations in number of young fledged (other than predation) were caused by the number of nestlings hatched and presence of a second brood. Both early arrival and an early first brood improved first-brood success and were necessary for a second brood. Not all birds which arrived early bred early enough for a second brood. First-brood hatching date was strongly negatively correlated with pre-breeding prey availability but not significantly related to vegetation structure. Thus by using vegetation as a clue to habitat quality, some pairs suffered reduced breeding success. This result implies that birds may not be able adequately to assess prey density directly at the time of territory establishment. The critical period for food availability may not be the period of peak demand (nestling period), when food is relatively abundant, but is probably the pre-breeding period when females must accumulate reserves for eggs and when the food supply is poor. Food supply during this period may determine the timing of breeding and the ability to rear a second brood, and may thus have a greater effect on breeding success.     

The application of temperature data loggers for remotely monitoring the nests of Emei Shan Liocichla (Liocichla omeiensis)

Temperature data loggers (TDL) are mostly used to monitor avian incubation behavior in bird studies. In this paper we demonstrate how TDL can also be used to determine different breeding stages and nest success of the vulnerable Emei Shan Liocichla (Liocichla omeiensis). All nests that contained at least one egg were divided into two groups. Group I included six nests monitored traditionally by the observers' visits, while Group II included eight nests monitored by TDL. Group I and Group II were visited every 1-4 days and 7 days, respectively, to check nest contents and status (e.g., active vs. inactive, and the breeding process) until fledging or nest failure. The time of each observation was recorded to verify the interpretation of TDL. The data recorded by TDL were converted into line graphs of temperature against time and assessed visually. The results indicated that TDL can reliably identify different breeding stages and estimate daily nest survival rates (DSR) and total nest success. The nest success of Group II (0.3015) was higher than that of Group I (0.2387), suggesting that deployment of TDL did not negatively influence nest survival rate of Emei Shan Liocichla. In contrast to traditional nest visits, TDL minimized disturbance by observers and provided a more precise estimate of nest survival. We suggest that TDL should be used more widely in studies of the breeding ecology of rare and endangered birds.     

紫蓬山区三种鹭种群繁殖成效的研究

：作者１９９６年４～７月在紫蓬山区国家级森林公园,对白鹭、池鹭和夜鹭繁殖种群的数量和繁殖成效进行了研究。结果表明：三块样地中,夜鹭的种群平均密度最大,白鹭的种群平均密度最小;白鹭、池鹭和夜鹭的种群繁殖生产力分别为２３７４ｉｎｄ／ｈｍ２、１４４１ｉｎｄ／ｈｍ２和２０１２ｉｎｄ／ｈｍ２;繁殖成效分别为５２０％、５５１％和４５１％。繁殖成效与巢位高度有关,低位巢卵损失率高,高位巢雏丢失率高。     

Conspecific nest parasitism in the Pied Avocet Recurvirostra avosetta

Evidence for the occurrence of conspecific nest parasitism (CNP) in Pied Avocets Recurvirostra avosetta is presented. Clutches of more than four eggs had obviously been produced by more than one female but were incubated by only one pair each. Minimum estimates for the frequencies of parasitized clutches and parasitic eggs were 3.3% and 1.3% respectively. CNP increased in frequency in colonies with higher nest densities. The frequency of CNP was unaffected by the rate of nest failures early in the season. On average, parasitic eggs were laid earlier in the season than the majority of non-parasitic eggs. Parasitic Avocets usually deposited their eggs during the laying period of host nests. Parasitized nests had significantly longer incubation periods than unparasitized nests. Hatching success in supernormal clutches was insignificantly reduced compared with four-egg clutches. The annual breeding success of individuals with parasitized clutches was considerably (but not significantly) higher than those of non-parasitized individuals. This was probably due to the fact that parasites chose to deposit their eggs in dense colonies whose members had significantly higher breeding success than the individuals in loose colonies. In colonies with a high rate of CNP, the frequency of clutches of more than five eggs increased. These clutches had little chance of survival.     

Breeding biology and breeding success of the Lesser Grey Shrike Lanius minor in a stable and dense population

The Lesser Grey Shrike Lanius minor is highly endangered throughout Europe, having declined markedly in abundance and range. Long-term changes in climate and agricultural practices have been identified as the main reasons for its decline. To determine which factors influence short-term changes in breeding success, we examined several aspects of its breeding biology. Our investigation revealed that our study area bears a large and stable population of this species. In 1996 and 1997, we recorded 84 and 77 breeding pairs in an area of 20 km², with an average of 4.20 and 3.85 pairs/km² respectively. Data on breeding density, clutch size and fledging success from 1989 to 1997 (excluding 1992) indicate a stable breeding population with a constant high breeding success. Reproductive success declined through the season, mainly through seasonal variation in clutch size rather than chick mortality. However, breeding success was generally high (69% and 79% of the nests produced chicks], with low hatching failure and few nest losses. The main cause of breeding failure was nest predation (at least 50% of nest losses), mainly by magpies (at least 66% of depredated nests). Although in this population the Lesser Grey Shrike tends to aggregate in clusters, breeding density had no obvious effect on breeding success and nest predation.     

Factors influencing Cinnamon Teal nest attendance patterns

Patterns of nest attendance in birds result from complex behaviours and influence the success of reproductive events. Incubation behaviours vary based on individual body condition, energy requirements and environmental factors. We assessed nest attendance patterns in Cinnamon Teal Spatula cyanoptera breeding in the San Luis Valley of Colorado in 2016–2017 using trail and video cameras to observe behaviours throughout incubation. We evaluated the effect of temporal, life‐history and environmental covariates on the frequency and duration of incubation recesses as well as the incubation constancy. There was considerable model uncertainty among the models used to evaluate recess frequency. Recess duration varied according to the interaction between nest age and a quadratic effect of time of day, with hens on older nests taking longer recesses in the afternoon and hens on nests earlier in incubation taking longer recesses in the morning and evening. Incubation constancy decreased with higher ambient temperatures in the study area. This study provides evidence that Cinnamon Teal modify their behaviour during incubation according to the age of the nest and the time of day. These results improve our knowledge of Cinnamon Teal breeding ecology and shed light on the behaviours that fast‐lived species may use to cope with environmental factors during nesting.     

Handicapped females receive more feedings during incubation from their mates: support for the female nutrition hypothesis

The female nutrition hypothesis posits that provisioning intensity of incubating females by their mates may depend on female needs and ensure proper incubation and a corresponding high hatching and breeding success of breeding pairs. Here, we have handicapped female pied flycatchers Ficedula hypoleuca at the beginning of incubation by clipping two primaries on each wing and filmed nests during incubation and later nestling provisioning to estimate male involvement in incubation feeding at the nest and in offspring care. Incubation feeding was more frequent at late nests. Correcting for this seasonal effect, incubation feeding was significantly affected by treatment and twice as high at experimental as at control nests. There was no effect of the experiment on female incubation attendance. The handicap did not result in any effect on hatching and breeding success, nestling growth and male or female provisioning and mass at the end of the nestling period. Males adjust their incubation feeding activity at the nest to female energetic requirements during incubation.     

The reproductive success of Blackbirds Turdus merula in relation to habitat structure and choice of nest site

The reproductive success of a population of Blackbirds Turdus merula occupying farmland and woodland was studied over 3 years to investigate the effects of habitat on breeding success. Territory distribution was patchy in both farmland and woodland; some areas were unoccupied, while other areas were occupied at variable densities. Habitat structure appeared to influence occupation: the index of habitat complexity ("cover score") was higher in occupied areas than in unoccupied areas and high-density territories had higher cover scores than low-density territories. However, habitat structure had no significant effect on reproductive success because the cover scores of territories where pairs were successful did not differ significantly from those of territories where there were no successful breeding attempts. There was no evidence of differential mortality rates in adults according to habitat. The height, bulk and exposure of c. 430 nests were measured to determine the effect of nest and nest-site characteristics on reproductive success. Nest exposure was the only feature that differed between successful and failed nests, successful nests being less exposed than failed nests. The major cause of breeding failure was nest predation, but the effect of nest exposure operated only during the laying and incubation period and not during the nestling period. The significance of habitat structure for variation in population densities between habitats is discussed.     

Individual variation in behavioural responsiveness to humans leads to differences in breeding success and long‐term population phenotypic changes

Whether human disturbance can lead to directional selection and phenotypic change in behaviour in species with limited behavioural plasticity is poorly understood in wild animal populations. Using a 19‐year study on Montagu′s harrier, we report a long‐term increase in boldness towards humans during nest visits. The probability of females fleeing or being passive during nest visits decreased, while defence intensity steadily increased over the study period. These behavioural responses towards humans were significantly repeatable. The phenotypic composition of the breeding population changed throughout the study period (4–5 harrier generations), with a gradual disappearance of shy individuals, leading to a greater proportion of bolder ones and a more behaviourally homogeneous population. We further show that nest visit frequency increased nest failure probability and reduced productivity of shy females, but not of bold ones. Long‐term research or conservation programmes needing nest visits can therefore lead to subtle but relevant population compositional changes that require further attention.