Visual fields in the Black-crowned Night Heron Nycticorax nycticorax: nocturnality does not result in owl-like features

Compared with diurnally active species, the eyes of nocturnally active herons (Ardeidae) are relatively larger and more widely separated. These features are found in comparisons between the nocturnally foraging Black-crowned Night Heron Nycticorax nycticorax and the diurnally active Cattle Egret Bubulcus ibis. Casual viewing of the Black-crowned Night Heron gives the impression of a somewhat owl-like appearance, with an apparently wide degree of binocular overlap. Visual fields and eye movements were determined in two alert, restrained Black-crowned Night Herons with the use of an ophthalmoscopic technique. A wide degree of binocular overlap was not confirmed, and the Black-crowned Night Heron's visual field closely resembles those of diurnally foraging herons (Western Reef Heron Egretta gularis schistacea , Squacco Heron Ardeola ralloides , Cattle Egret). The Black-crowned Night Heron's binocular field is vertically long and narrow (maximum width 22̀), with the bill placed approximately at the centre. Monocular and cyclopean field widths in the horizontal plane equal 171̀ and 320̀, respectively. Retinal binocular overlap can be abolished by eye movements. There is a blind sector (10–13̀ wide) at the margin of each eye's optical field, and this results in the functional retinal binocular field being much narrower than the optical binocular fields. It is these blind sectors which give rise to the appearance of a much wider binocular field. The visual field characteristics of this heron species may be best understood in relation to the foraging technique of capturing agile, evasive prey directly in the bill. The comparatively large size of the Black-crowned Night Herons' eyes may be associated with activity over a wide range of natural light levels but does not give rise to binocular fields larger than those of diurnal heron species.     

BREEDING BEHAVIOUR OF THE GREAT WHITE EGRET

Tomlinson, D. N., S. 1976. Breeding behaviour of the Great White Egret. Ostrich 47:161-178.

The breeding displays of the Great White Egret Egretta alba are discussed but further observations are needed for statistical analysis. In support of Curry-Lindahl (1971). the ethology of the species in combination with other evidence indicates that it is more closely related to the genus Ardea than to Egretta and it is suggested that it be reclassified accordingly. In comparison with other Ardeidae. E. albu chicks are highly tolerant of each other, resulting in an estimaed high fledgling success rate.     

ESTIMATION OF THE DAILY FOOD INTAKE OF PISCIVOROUS BIRDS

Tomlinson, D. N. S. 1979. Interspecific relations in a mixed heronry. Ostrich 50:193-198.

Fortnightly censuses were conducted at a heronry in Lake Kyle, Rhodesia, from January toMay1974, and while certain species (Reed Cormorant Phalacrocorax africanus, Grey Heron Ardea cinerea and Black headed Heron Ardea melanocephala) continued to arrive in small parties throughout the breeding season, others (Great White Egret Egretta aha, Cattle Egret Bubulcus ibis and Night Heron Nycticorax nycticorax) exhibited a high degree of breeding synchrony. P. africanus showed a significant nesting association with A. cinerea and A. melanocephala, while N. nycticorax was associated with C. albus. B. ibis did not show any significant nesting association with the other species.     

无锡太湖地区夜鹭及白鹭繁殖生物学研究

1999年 4～ 6月对分布在无锡地区的夜鹭 (Nycticoraxnycticorax)和白鹭 (Egrettagarzetta)的繁殖生物学进行了调查研究 ,调查地面积约 2 72 37 5m2 ,植被以马尾松 (Pinusmassoniana)和香樟树 (Cinnamomumhupehanum)为主。研究结果表明 :栖息地共有鹭巢近万个 ,平均密度为 0 36个 /m2 ,每棵树上平均巢数为1 0 6个 ,最多达 2 5个 /棵树 ;平均窝卵数夜鹭为 3 5 5枚 ,白鹭为 4 89枚 ;平均窝雏数夜鹭为 2 6 8只 ,白鹭为3 96只 ;孵化期白鹭为 1 9～ 2 1天 ,夜鹭为 2 2～ 2 3天 ;孵化成功率白鹭为 84 2 5 % ,夜鹭为 75 46 % ;白鹭雏鸟主要以小型鱼类和虾类为食 ,夜鹭雏鸟主要以鱼类和两栖类为食。     

海南3种鹭越冬行为的比较

于2004年1～2月选择了3种鹭类作为研究对象,采用瞬时扫描观察的方法,就其越冬行为差异进行了比较。3种鹭昼间主要行为有所不同,苍鹭(Ardea cinerea)主要以站立和休息为主,白鹭(Egretta garzetta)主要以取食和休息为主,而大白鹭(E.alba)主要以站立和取食为主。本文对3种鹭的取食行为进行了比较分析,3种鹭的取食行为比例从高到低依次为白鹭(40%～60%)、大白鹭(20%～40%)和苍鹭(0.1%以下)。最后,对3种鹭不同的取食对策进行了讨论。     

Diurnal activity patterns of three heron species in Queen Elizabeth National Park,Uganda

Kasoma, P.M.B. 2000. Duirnal activity patters of three heron species in Queen Elizabeth National Park, Uganda. Ostrich 71(1): 127–130.

Observations of activities were carried out over 12 h periods on the Goliath Heron, Grey Heron and Great White Egret along the shores of Lake Edward and Kazinga Channel. Behaviour was classified into three major categories: foraging, loafing and other behaviour. For all three species, foraging went on throughout the daylight hours but the level was variable both in the dry and wet seasons and between species. For all three species, foraging basically consisted of standing-and-waiting. The Great White Egret spent more time foraging than the other two species. Overlap between species in foraging activity on an hourly basis was high during most hours of the day implying that ecological separation through temporal partitioning of daylight hours is negligible.     

Feeding ecology of the waterbirds in a tropical mangrove in the southeast Gulf of Mexico

ABSTRACT

Species that exploit the same type of environmental resources are defined as a guild, which have similar needs in the use of food or habitat. It was analyzed the diet of five waterbirds’ offsprings species (Neotropic Cormorant (Nannopterum brasilianus), Reddish Egret (Egretta rufescens), Boat-billed Heron (Cochlearius cochlearius), Snowy Egret (Egretta thula) and Great Egret (Ardea alba)), by prey identification and calculated the relative importance, overlap and breadth diet. The general diet of the piscivorous guild consisted of 17 fish species from 13 genera and eight families. The highest overlap was between the Reddish Egret and Boat-billed Heron. Fish species dominated the diets of all studied waterbirds, Poecilia velifera was the most abundant prey species in each of the birds, suggesting that they are abundant in the wetlands system of northern Yucatan. Diet overlap in waterbirds species depends on the use of resources and feeding habitat. Since reproductive success largely depends on the availability of food resources, mainly of resident or estuarine fishes. The information about diet is important for the conservation of waterbirds.     

Patterns of resource partitioning by nesting herons and ibis: How are odonata exploited?

Herons and ibis are colonially nesting waders which, owing to their number, mobility and trophic role as top predators, play a key role in aquatic ecosystems. They are also good biological models to investigate interspecific competition between sympatric species and predation; two processes which structure ecological communities. Odonata are also numerous, diverse, mobile and can play an important role in aquatic ecosystems by serving as prey for herons and ibis. A relationship between prey size and bird predator has been observed in Numidia wetlands (NE Algeria) after analyzing food boluses regurgitated by six species of birds (Purple Heron, Black-crowned Night Heron, Glossy Ibis, Little Egret, Squacco Heron and Cattle Egret) during the breeding period, which also shows a temporal gradient for the six species. Both the Levins index and preliminary multivariate analysis of the Odonata as prey fed to nestling herons and ibis, indicated a high degree of resource overlap. However, a distinction of prey based on taxonomy (suborder and family) and developmental stage (larvae or adults) reveals a clear size dichotomy with large-sized predators (Purple Heron, Black-crowned Night Heron and Glossy Ibis) preying on large preys like Aeshnids and Libellulids and small-sized predators feeding mainly on small prey like Zygoptera. Overall, the resource utilization suggests a pattern of resource segregation by coexisting nesting herons and ibis based on the timing of reproduction, prey types, prey size and foraging microhabitats.     

Waterbirds (other than Laridae) nesting in the middle section of Laguna Cuyutlán, Colima, México

Laguna de Cuyutlán, in the state of Colima, Mexico, is the only large coastal wetland in a span of roughly 1150 km. Despite this, the study of its birds has been largely neglected. Between 2003 and 2006 we assessed the waterbirds nesting in the middle portion of Laguna Cuyutlán, a large tropical coastal lagoon, through field visits. We documented the nesting of 15 species of non-Laridae waterbirds: Neotropic Cormorant (Phalacrocorax brasilianus), Tricolored Egret (Egretta tricolor), Snowy Egret (Egretta thula), Little Blue Heron (Egretta caerulea), Great Egret (Ardea alba), Cattle Egret (Bubulcus ibis), Black-crowned Night-heron (Nycticorax nycticorax), Yellow-crowned Night-heron (Nyctanassa violacea), Green Heron (Butorides virescens), Roseate Spoonbill (Platalea ajaja), White Ibis (Eudocimus albus), Black-bellied Whistling-duck (Dendrocygna autumnalis), Clapper Rail (Rallus longirostris), Snowy Plover (Charadrius alexandrinus), and Black-necked Stilt (Himantopus mexicanus). These add to six species of Laridae known to nest in that area: Laughing Gulls (Larus atricilla), Royal Terns (Thalasseus maximus), Gull-billed Terns (Gelochelidon nilotica), Forster's Terns (S. forsteri), Least Terns (Sternula antillarum), and Black Skimmer (Rynchops niger), and to at least 57 species using it during the non-breeding season. With such bird assemblages, Laguna Cuyutlán is an important site for waterbirds, which should be given conservation status.     

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。     

Richards's equation and nonlinear mixed models applied to avian growth: why use them?

Postnatal growth is an important life‐history trait that varies widely across avian species, and several equations with a sigmoidal shape have been used to model it. Classical three‐parameter models have an inflection point fixed at a percentage of the upper asymptote which could be an unrealistic assumption generating biased fits. The Richards model emerged as an interesting alternative because it includes an extra parameter that determines the location of the inflection point which can move freely along the growth curve. Recently, nonlinear mixed models (NLMM) have been used in modeling avian growth because these models can deal with a lack of independence among data as typically occurs with multiple measurements on the same individual or on groups of related individuals. Here, we evaluated the usefulness of von Bertalanffy, Gompertz, logistic, U₄ and Richards's equations modeling chick growth in the imperial shag Phalacrocorax atriceps. We modelled growth in commonly used morphological traits, including body mass, bill length, head length and tarsus length, and compared the performance of models by using NLMM. Estimated adult size, age at maximum growth and maximum growth rates markedly differed across models. Overall, the most consistent performance in estimated adult size was obtained by the Richards model that showed deviations from mean adult size within 5%. Based on AICc values, the Richards equation was the best model for all traits analyzed. For tarsus length, both Richards and U₄ models provided indistinguishable fits because the relative inflection value estimated from the Richards model was very close to that assumed by the U₄ model. Our results highlight the bias incurred by three‐parameter models when the assumed inflection placement deviates from that derived from data. Thus, the application of the Richards equation using the NLMM framework represents a flexible and powerful tool for the analysis of avian growth.     

Allometric relations in three species of finches (Aves: Fringillidae)

Static nestling, adult and ontogenetic allometry were analysed in three species of finches. Static nestling allometry was very similar across age in early ontogeny and among species and could be approximated by a single matrix of phenotypic variances and covariances. The first eigenvector of this matrix showed negative allometry of bill and tarsus to mass, but positive for wing length to mass. Adult static allometry was also very similar among species, but differed from nestling pattern. In adults the bill had a positive allometry in relation to tarsus and wing, but negative to mass, while tarsus and wing were unrelated to mass. The ontogenetic allometry in each species was very similar to nestling static allometry. Viewed in relation to final size, bill characters grew more slowly than body characters, but for a longer time, which created the difference between adult and nestling allometric patterns. There were differences among species both with regard to elevation and slope of allometric coefficients, suggesting that the differences among species came about by changes in the three fundamental ontogenetic parameters namely growth rate, onset of growth and offset of growth.     

三参数增长模型拟合:以季风常绿阔叶林中两个优势乔木种群为例

Logistic、Mitscherlich、Gompertz方程是一类三参数饱和增长曲线模型,广泛地应用于许多学科领域．本文基于logistic方程饱和值K估计的三点法、四点法,推导出Mitscherlich、Gompertz方程K值的三点法、四点法估计公式,并以南亚热带季风常绿阔叶林中两种优势乔木厚壳桂、黄果厚壳桂种群为例,先用三点法或四点法估计出K值,再通过线性回归与非线性回归相结合的方法,可获得三个增长模型中三个参数的最优无偏估计．实例研究表明,两个优势种群增长数据均符合三个增长模型,但更符合增长曲线呈S形的logistic、Gompertz方程,且以logistic方程最适合于观察;黄果厚壳桂种群增长快于厚壳桂种群．     

STUDIES OF THE PURPLE HERON,PART 2: BEHAVIOUR PATTERNS

Tomlinson, D. N. S. 1974. Studies of the Purple Heron, Part 2: Behaviour patterns. Ostrich 45: 209–223.

Some aspects of Purple Heron Ardea purpurea behaviour have been covered although the study is not complete. Further observations are needed, especially on pair formation, nest building and copulation. Many of the displays described for the Ardeidae are clearly homologous and only slight differences exist. The throat puffing component in the Aggressive Upright Display appears unique to A. purpurea as does the clappering and sudden retraction of the neck in the Stretch Display. Birds raised in captivity provided valuable information on agonistic behaviour patterns and the behaviour of young.     

On Gompertz growth model and related difference equations

Within the context of the dynamics of populations described by first order difference equations a datailed study of the Gompertz growth model is performed. This is mainly achieved by proving several theorems for a class of difference equations generalizing the Gompertz equation. Some interesting features of the discrete Gompertz model, not exhibited by other well known growth models, are finally pointed out.     

Nestling growth in the African fish eagle in Uganda

Nestling African fish eagles Haliaeetus vocifer (Daudin, 1858) in Queen Elizabeth National Park (QEP), Uganda, attained and exceeded the adult body weights of their respective sexes by fledging time. The growth curves conformed with the sigmoid form of most animal species. The overall growth rate, K (g/day), was low, averaging 0.077 ± 0.017 g/day and the time t_10–90 required to complete growth from 10 to 90% of the asymptotic weight was c. 42 days. Brood size and hatching order did not significantly influence growth rates but the sex of the young did. The tarsus, femur and humerus reached adult sizes by fledging time but the standard wing did not.     

Provisioning and growth in chicks of Wilson's storm-petrels (Oceanites oceanicus) on King George Island, South Shetland Islands

We present data on chick growth and chick feeding in Wilson's storm-petrel (Oceanites oceanicus) in a colony on King George Island, South Shetland Islands. Chicks were repeatedly weighed and the weight differences over 24 h were corrected for metabolic loss in order to obtain an estimation of meal sizes. Chicks were fed on 93% of the nights (n=688 nights). The average meal size for a single feeding was 8.5 g. Chicks received on average 1.2 feedings per night. These results are compared with data for this species from other locations. There was a trend for increased meal sizes from northern to southern populations, parallel to an increase in the adult mass, indicating that Wilson's storm-petrels carry optimal meal sizes according to their body size and may take advantage of increased food abundance by increasing feeding frequencies. We describe chick growth and discuss the influence of egg size, hatching date and feeding frequency on chick growth. The egg size had a positive influence on tarsus growth and body mass of chicks. Later-hatched chicks started wing growth and finished mass growth at a younger age and reached lower peak masses, indicating that late chicks may adapt to the restricted breeding season in their Antarctic breeding grounds by a more rapid development, but will fledge with a lower degree of development and less resources. Accepted: 22 May 2000     

The component helminth community in six sympatric species of Ardeidae

We studied the helminth communities in 6 sympatric species of Ardeidae (Ixobrychus minutus (Linnaeus, 1766), Nycticorax nycticorax (Linnaeus, 1758), Bubulcus ibis (Linnaeus, 1758), Egretta garzetta (Linnaeus, 1766), Ardea cinerea (Linnaeus, 1758), and Ardea purpurea (Linnaeus, 1766)) from "La Albufera de Valencia," Spain. The survey revealed 13 species of helminth parasites: 5 digeneans, 2 cestodes, and 6 nematodes. The component helminth communities of the Ardeidae examined are depauperate and conform to the pattern typically found in isolationist communities, probably because of their high trophic dependence on a few prey species. Evenness was positively correlated with richness and abundance, but host body weight was not correlated with the number of helminth species or with the total number of helminths. Ardea cinerea is more heavily infected than E. garzetta by Apharyngostrigea cornu, and B. ibis is more heavily infected than both Ardea cinerea and E. garzetta by Desportesius spinulatus. Apharyngostrigea cornu was positively associated with Desmidocercella numidica and D. spinulatus in A. cinerea.     

颍上八里河自然保护区鹭卵3种重金属残留分析

2005年5月,采集了淮河地区颍上八里河集群繁殖的夜鹭(Nycticorax nycticorax)和小白鹭(Egrettagarzetta)鸟卵共18枚,用原子吸收法测定了卵壳、内容物中重金属Cd、Pb、Cr的残留量。结果表明,所有卵壳样品中均检出一定水平的Cd、Pb和Cr残留量,夜鹭卵壳中重金属残留量为Pb>Cr>Cd,小白鹭卵壳中重金属残留量为Cr>Pb>Cd,卵壳中Pb和Cr残留量的种间差异都不显著,但Cd的种间差异显著;在2种鹭卵内容物中,Cr都被检出,在夜鹭卵内容物样品中,Pb只被部分检出,Cd在2种鹭卵内容物样品中都没有被检出,3种重金属在内容物中残留量的种间差异都不显著。2种鹭卵壳中Pb和Cd残留量极其显著地高于卵内容物,但Cr的这种残留分布上的差异不显著。本研究进一步证明卵壳可用作重金属污染物的指示物,监测和评价湿地生态系统中重金属的污染状况。