Showing papers on "Heron published in 2006"

Contamination and Biomarkers in the Great Blue Heron, an Indicator of the State of the St. Lawrence River

Abstract: In 1996–1997, nine breeding colonies of the great blue heron on the St. Lawrence River and its estuary (Quebec, Canada) were investigated in the framework of a biomonitoring program. Fledglings from colonies in freshwater were more contaminated with mercury, PCBs and many organic contaminants than those from estuarine colonies. The level of contamination in the St. Lawrence River is generally below the levels of toxicological effects for the great blue heron. The molar ratio of retinol: retinyl palmitate in heron eggs was correlated with total PCBs (r=0.79) and Mirex (r=0.90). In plasma, all biochemical parameters were significantly different between freshwater and marine colonies. Plasma retinol concentrations at the Dickerson and Herons colonies were significantly lower compared with those at Grande Ile (p<0.05) and Steamboat (p<0.001). Based on retinoid and β-carotene concentrations in eggs, low plasma retinol was not associated with possible dietary deficiency. Plasma retinol was negatively correlated with many PCB congeners, total PCBs (r=−0.78), p,p′-DDE, trans-nonachlor and α-HCH. Similarly, the hormone T3 was correlated with many PCB congeners, total PCBs (r=−0.69) and the same organochlorine chemicals. Plasma LDH concentrations were different among freshwater colonies, Grande Ile and Herons colonies having LDH values significantly greater than those of Steamboat (respectively, p<0.05 and p<0.01). Globally, the health status of the St. Lawrence great blue heron population was judged to be acceptable, however, several biomarkers indicated positive responses to contaminants.

Seasonal metabolism of juvenile green turtles (Chelonia mydas) at Heron Island, Australia

Abstract: We investigated seasonal changes in the energetics of juvenile green turtles (Chelonia mydas (L., 1758)) (9.8–23.8 kg) from a resident population on the southern Great Barrier Reef. Doubly labeled ...

The influence of climate variability on numbers of three waterbird species in Western Port, Victoria, 1973–2002

Abstract: Seasonal and annual movements of Australian waterbirds are generally more complex than those of their Northern Hemisphere counterparts, and long-term data are needed to understand their relationships with climatic variables. This paper explores a long-term (1973-2002) set of waterbird counts from coastal Victoria and relates them to climatic data at local and continental scales. Three species (Black Swan Cygnus atratus, White-faced Heron Egretta novaehollandiae and Grey Teal Anas gracilis) were chosen for this analysis. Black Swans have large local breeding populations near the study region; White-faced Herons have smaller local breeding populations and Grey Teal breed extensively in ephemeral inland floodplains, such as those in the Murray-Darling Basin. All showed significant relationships with streamflow, regional rainfall and the Southern Oscillation Index (SOI) at appropriate scales and time-lags, with streamflow explaining the most variance. Black Swans showed a strong seasonal cycle in abundance and local climate variables had the greatest influence on the counts. Numbers were positively correlated with streamflow in southern Victoria three to six seasons before each count. Broader-scale climatic patterns were more important for the other two species. Numbers of White-faced Herons were positively correlated with streamflow or rainfall over various parts of Australia seven to nine seasons before each count. Numbers of Grey Teal showed weak seasonal cycles, and were negatively correlated with rainfall in Victoria or the Murray-Darling Basin in the seasons before or during each count, and positively with streamflow in the Murray-Darling Basin 15-18 months before each count.

Environmental factors affecting biomass and distribution of stuckenia pectinata in the heron lake system, minnesota, usa

Abstract: The Heron Lake System historically has been an important resource for waterfowl in Southern Minnesota, USA. In the early 1900s, the system was a major nesting, feeding, and staging area for breeding and migrating waterfowl mainly due to the extensive growth of sago pondweed, Stuckenia pectinata. In recent years, the abundance of S. pectinata has decreased dramatically. We conducted a study from 2002 through 2003 to identify factors limiting the success of S. pectinata. Distribution and biomass of S. pectinata differed significantly over the years of this study. Biomass was related to environmental factors, including water transparency and water temperature early in the season. Water transparency during May (time of early growth) had a negative relationship with maximum biomass at each site over all years. Water temperature had a positive relationship with increases in seasonal biomass yield of S. pectinata in the Heron Lake System.

The distribution and status of waterbirds around the coast and coastal wetlands of the Northern Territory

Abstract: Prior to 1990 there had been little survey work done to assess the distribution and status (primarily their abundance, density and seasonality) of any of the Northern Territory coastal fauna. With the possible exception of some Magpie Goose aerial surveys and some work done in Kakadu National Park, there had also been very little done on assessing this for Top End wetland fauna. Locating and documenting this information for our Top End fauna, prior to instigating necessary management actions, is a vital step in ensuring the future conservation of these animals and their habitats. Commencing in 1990 with the Parks and Wildlife Service of the Northern Territory, I began a series of extensive aerial and ground surveys to locate and document the distribution and status of selected faunal assemblages (mostly aquatic birds, marine turtles and cetaceans) along the Northern Territory coastline, on offshore islands and in Top End coastal wetlands. This is the fourth in a series of reports being written from information collected during these surveys. Individual reports are based on the different species groups surveyed. (For the purposes of these reports the aquatic birds were considered separately as shorebirds, seabirds and waterbirds, even though shorebirds are also waterbirds). The three previous reports in the series considered waterbird and seabird breeding colonies, and shorebirds. This current report summarises the distribution and status of 66 selected migratory and resident waterbird species (i.e. not including shorebirds). It covers all species of waterbirds not previously included in the earlier report dealing only with colonial breeding waterbirds. This current report also details the non-breeding distribution and status of the (13) colonial breeding species which were only discussed in terms of their breeding colony status in the earlier report. As with each of the previous reports, this current report has been produced as an overview of waterbird distribution and status, with the main aim of assisting future management and research priorities. More detailed papers on species and areas will be written at a later date following further analysis of the data. Over the 16 year period I made nearly 70 000 separate records, totalling a cumulative 5.6 million individuals in the survey area. Of these, nearly 30 000 records, totalling a cumulative 2.6 million individuals, were of the waterbird species detailed in this report. (For the purpose of these reports a record is a single count that differs by species, location and/or time). These records and other information gathered during my aerial and ground surveys have clearly shown that the Top End floodplains and coastal wetlands of the Northern Territory support internationally important numbers of many species of waterbirds in highly favourable habitats. Waterbirds were recorded on all parts of the Northern Territory coast, on many of the islands and throughout the vast areas of tidal and freshwater wetland. Within the survey area of the Top End, 31 separate wetland areas were documented as regionally significant for these taxa. Many of these are of national significance and at least 22 are of international importance (they would for example qualify for Ramsar listing) based solely on numbers of waterbirds. This is very much a minimum number of areas, as many of these areas could be further divided and still qualify; such are the numbers of birds present. Further, the addition of shorebird numbers to many other wetland areas would see them also elevate to Ramsar status on numbers of waterbirds and shorebirds combined. There are also many additional wetland areas that would qualify for Ramsar (or East Asian-Australasian Shorebird Network) status with shorebird numbers alone. These have been discussed in the previous report in this series (Chatto, 2003). Waterbirds were recorded in greatest numbers in several areas. Of particular importance were the wetlands around the Keep River/Legune Station area in the far south west, and the wetlands between the Moyle and Finniss Rivers, and between the Adelaide River and Murgenella Creek in the north west of the Top End. Further important areas across the northern part of the Top End included the wetlands of the Liverpool/Tomkinson Rivers and the Glyde/Goyder Rivers (Arafura Swamps) and the southern part of Arnhem Bay. Along the east coast of the Top End most waterbirds were recorded in wetlands associated with the northern parts of Blue Mud Bay, the Roper River area and the Port McArthur area in the south east. Most of the species discussed in this report were found throughout the survey area, and many were found in greater numbers than previously suspected. Of the resident species, Magpie Goose, all four species of egrets and Australian White Ibis were recorded as the most abundant waterbirds. Other extremely abundant resident waterbird species included Pied Heron, Nankeen Night Heron and Masked Lapwing. Of the species that have most of their population leave the area to breed (either regularly or irregularly), many were recorded in large abundances when they were present in the survey area. These included both whistling-duck species, Grey Teal, Glossy and Straw-necked Ibis, Brolga, Black-winged Stilt and Whiskered Tern, and the migratory Gull-billed, Common and White-winged Black Tern. Species that do not normally appear in large groups, but for which the survey area was nationally important because of their high total numbers, included Green Pygmy-goose, Great-billed Heron, Black-necked Stork, Osprey, Brahminy Kite, White-bellied Sea Eagle Chestnut Rail and Comb-crested Jacana. Many of the waterbirds discussed in this report breed in the survey area. Around 13 species breed in large mixed species breeding colonies. The breeding of these colony species is covered to a certain extent in this report, but have been discussed in much greater detail in a previous report in this series (Chatto 2000b). Magpie Goose breeding was recorded and is discussed but has been reported on in more detail by other authors. The breeding of most of the remaining resident waterbirds was not well studied in these surveys. With the exception of the large and obvious stick nests belonging to Blacknecked Stork and the large coastal raptors, little emphasis was given to searching for single breeding pairs in these surveys. Waterbirds, like most of the other fauna of the Top End of the Northern Territory, are in a unique position. Not only is there an immense amount of habitat which supports large populations of many species, but most of the area is very remote and has not been subject to many of the pressures associated with large human populations. Although this is likely to remain the case for the short term at least, it is equally likely that the pressures of human expansion within Australia, especially in coastal areas, will see some of this area targeted for development, such as broad-acre irrigation schemes, at some stage in the not too distant future. It is for this eventuality that we must be prepared. We must ensure the security of the more significant of these areas before problems arise. Locating key coastal fauna sites and documenting them in this series of reports is the first step in that process.

Annotated Atlas and Implications for the Conservation of Heron and Egret Nesting Colonies in the San Francisco Bay Area

Abstract: Nesting distribution, abundance, and reproductive success of colonially nesting herons and egrets in the central coastal region of California surrounding the San Francisco Estuary were analyzed from 1991 to 2005. Nesting activity among nine major wetland subregions was compared with regard to nesting distribution, nest survivorship, productivity of successful nests, habitat characteristics, and intraseasonal timing. An average of 73 active colony sites y-1 supported approximately 62 Great Blue Heron (Ardea herodias) colonies, 25 Great Egret (Ardea alba) colonies, 13 Black-crowned Night-Heron (Nycticorax nycticorax) colonies and twelve Snowy Egret (Egretta thula) colonies each year. Regional nest abundances were stable or increasing in all species. Annual changes in nest abundance were consistent with shifts in colony site preference as wetland suitability and disturbance patterns fluctuate across years and over space. Decreases in colony size were significantly related to higher rates of nest mor...

Selective Foraging of Grey Heron (Ardea cinerea) in Relation to Density and Composition of the Littoral Fish Community in a Submontane Dam Reservoir

Abstract: Grey Herons foraged in a high number only in one of three preferred foraging areas in the Dobczyce Reservoir, S. Poland: (1) the backwater area at the main tributary inlet (MTI), (2) the shore of the near-dam pool (NDP), and (3) shallow lateral bay (SLB). Median value of the fraction of herons foraging in MTI was 64% of all counted in the reservoir in 2001-2002 despite the smallest fish density there (2 times smaller than in NDP, and by one order of magnitude than in SLB). Roach (Rutilus rutilus) was the most abundant both in the heron diet (13 species) and in littoral fish communities (8 species). Total length of prey ranged within 4.2-26.5 cm. The individual size range of littoral fish was similar (4.6-31.5 cm). However, the size distributions in three foraging areas and in heron diet were different. Fish longer than the median total length of heron prey, i.e. ≥8 cm in total length constituted 51.9% of heron diet, 34.7% of the fish community in MTI, 8.5% in the psammolittoral of NDP, and only 5...

Sacred Ibis and Gray Heron Predation of Cape Cormorant Eggs and Chicks; and a Review of Ciconiiform Birds as Seabird Predators

Abstract: The literature indicates that predation of seabirds by ciconiiform birds is limited to terns and is generally of little impact. We monitored predation of the eggs and chicks of Cape Cormorants (Phalacrocorax capensis) by Sacred Ibises (Threskiornis aethiopicus), and Gray Herons (Ardea cinerea) for 46 days over three breeding seasons at Penguin Island, Lambert’s Bay, South Africa. The ibises were observed to take at least 152 cormorant eggs and chicks and 37 heron chicks. Extrapolation of the results to the full season of availability indicates that these ciconiiform predators may take as many as 960 cormorant eggs or chicks in a season. If so, they would be the third most serious cause of mortality among the 4,800 pairs of Cape Cormorants at Penguin Island. The observed combined effect of ciconiiform predation was greater than that of the local, predatory, Khoisan Gulls (Larus (dominicanus) vetula). We document the seasonality and diel timing of predation, behavior of the predators, and the cormo...

On Heron triangles.

Abstract: There has previously been given a one-parameter family of pairs of Heron triangles with equal perimeter and area. In this note, we find two twoparameter families of such triangle pairs, one of which contains the known one-parameter family as a special case. Second, for an arbitrary integer n > 2 we show how to find a set of n Heron triangles in two parameters such that all triangles have equal perimeter and area.

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

Abstract: Laguna de Cuyutlan, 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 Cuyutlan, 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 Nightheron (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 Cuyutlan is an important site for waterbirds, which should be given conservation status.

Ardeid Nesting Colony Survey in Hainan, China

Abstract: A survey of ardeid nesting colonies in Hainan Province, China, was made between May and August 2004 and recorded 5,287 nests of four species (Little Egret Egretta garzetta, Cattle Egret Bubulcus ibis, Chinese Pond Heron Ardeola bacchus and Black-crowned Night Heron Nycticorax nycticorax), in 18 colonies in the northern area. Chinese Pond Heron was the dominant nesting species (62% of the total nests), while the Black-crowned Night Heron was the least abundant (4%). Numbers of the Chinese Pond Heron in Hainan is probably related to the presence of extensive ricefields in this area. Fewer numbers of nests of all species in the field were recorded compared with expected obtained from nest densities over a ricefield-dominated landscape in a previous study of ardeid nest abundance in central China. This suggests that nest density in central China could not be applied in Hainan and the assumption of 5 million nests in China requires further study. Based on available information for south China, numbers...

Sociality among Foraging Ardeidae: Does Plumage Coloration Influence Nearest-Neighbor Spacing?

Abstract: Increased sociality in herons, family Ardeidae, is often considered to be associated with the occurrence of white plumage. If white plumage increases sociality, we hypothesized that white-plumaged birds should forage closer to one another and dark birds should remain more solitary. We tested this hypothesis by investigating the inter-individual spacing (nearest neighbor distance) in two pairs of closely related species that differ in plumage coloration: (1) Great Blue Heron (Ardea herodias)/Great Egret (A. alba) and (2) Little Blue Heron (Egretta caerulea)/Snowy Egret (E. thula). All birds observed were in adult plumage. We recorded distances to nearest conspecific, nearest congeneric, nearest white (regardless of species) and nearest dark bird to each focal bird within a given (focal) pond. Because species occurred in varying numbers, we compared the observed mean distances with randomly generated distances based on the total number of birds in the pond. All observations were conducted under ste...

Schur Convexity of the Power-Type Generalization of Heron Mean

Abstract: The schur-convexity and the monotonicity of the power-type generalization of Heron mean with two positive numbers a,b in R~2_+ are discussed.Besides,two new inequalities are obtained.

Population Dynamics and Breeding Space Niche of Four Heron Species in Tanghai Wetlands

Abstract: The population dynamics and breeding behaviors of Black-crowned Night Herons (Nycticorax nycticorax), Egrets (Egtetta garzetta), Chinese Pond Herons (Ardeola bacchus) and Great Egrets (Casmerodius albus) were observed in Tanghai Wetlands, Hebei Province from August 2004 to July 2005. Further, we studied the relationship of nest space distribution and directly calculated the nest density of vertical and horizontal levels, the niche overlapping index and the niche breadth. The results showed that there were two breeding areas, named Area Ⅰ and Area Ⅱ. The maximum population occurred in the period from April to September and was approximately 5800 individuals. Area Ⅰ was occupied earlier than Area Ⅱ by approximately half a month. In the breeding period, Black-crowned Night Herons were dominant in numbers and most occupied the upper nests of the core areas. Great Egrets also took the upper nests but they have the smallest population. Most Egrets took the middle nests of the edges of the area. Chinese Pond Herons, with a smaller population than the Egret, mostly nested in the edges, but some of them also took the lower nests of the core area. On the whole, the vertical niche of Egrets is the widest, the horizontal niche of Black-crowned Night Herons is the widest and the niche breadth of Chinese Pond Herons is the largest. The nest distribution pattern is the most similar between Chinese Pond Herons and Black-crowned Night Herons, and the niche overlapping index of Chinese Pond Herons and Egrets is the largest. Black-crowned Night Herons and Great Egrets control Egrets and Chinese Pond Herons in competition. Rich food and the optimal ecological environments lead to plenty of herons in the wetlands. In addition, it is a distinguishing feature of the four species that nests are built in poplar trees over 22 m tall.

Local adaptation in the wedge-tailed shearwater (Puffinus pacificus)

Abstract: Models of speciation that involve adaptation to local environmental conditions rather than physical barriers have rarely been examined in vertebrate taxa. Seabirds offer a unique opportunity to test such models because they have the potential to disperse widely. This means that large-scale geographical barriers to gene flow are less likely. In addition, breeding colonies are constrained to forage locally, thus promoting the optimisation of life history and fitness-related morphological traits among colonies. Ultimately, these changes may lead to a reduction in gene flow and genetic divergence may ensue: the first step towards speciation. To explore adaptive models of speciation, the role of local foraging conditions in promoting molecular, morphological (including physiological) and behavioural divergence among breeding colonies of the wedge-tailed shearwater (Puffinus pacificus) was examined. To this end levels of variation in morphology and neutral genetic markers were measured among four spatially disjunct breeding colonies located in Australian waters (Rottnest Island, Raine Island, Heron Island and Lord Howe Island). In addition, data on foraging behaviour, chick developmental patterns and sensitivity to background environmental conditions (sea surface temperature) were obtained from two of these colonies representing climatic and oceanographic extremes for this species: the subtropical 'reef' colony (Heron Island) and Lord Howe Island, a temperate 'oceanic' colony. Results from the foraging behaviour and chick developmental component of this research suggests that wedge-tailed shearwaters are sensitive to fluctuations in sea surface temperature, and consistently use different foraging strategies during the chick rearing period in accordance with where they breed. Specifically, at Heron Island, birds use a 'dual-foraging' strategy involving alternative 'short' and 'long' trips. This strategy is consistent with adults self-provisioning from distant locations and chick provisioning from near colony locations. However, at Lord Howe Island, a dual foraging strategy was not observed, suggestive of a more productive environment. As an indirect result of divergent oceanographic regimes, chick developmental patterns between the two locations also differed; chicks at Lord Howe Island grow faster than those at Heron. However, when the differences in meal mass per night were accounted for, Heron Island chicks were consistently heavier than those at Lord Howe Island. Overall, the foraging and chick development data suggest that; (1) chick developmental patterns and foraging behaviour are coordinated in wedge-tailed shearwaters, (2) the foraging environment experienced by wedge-tailed shearwaters at Heron Island is less productive than at Lord Howe Island and (3) chicks at Heron Island appear to 'store' mass as an adaptation to consistently poor provisioning rates (driven by poor foraging conditions experienced by adults). The chick developmental pattern is likely to be driven by an obligate rather than a facultative mechanism because it is doubtful chicks can react to changing provisioning rates over the (small) period of time that the response took place. Within the general patterns of foraging, sex-specific differences were also evident. Females spent more time at sea resulting in a lower provisioning rate compared to males. The average maximum dive depth also differed according to sex, with males diving consistently deeper than females. The most parsimonious explanation for the differences is that competition has lead to niche partitioning at the foraging grounds, although direct evidence will be required to substantiate this hypothesis. Subtle differences in the extent of sex-specific foraging between Heron Island and Lord Howe Island could promote a barrier to gene flow via. reinforcement if inter-colony pairings result in lower provisioning to chicks. Again, further evidence will be required to test this idea. Morphological analyses highlighted significant variation within (sex-specific) and among breeding colonies. A canonical discriminant functions analysis was conducted using four traits: wing, tarsus, culmen and tail. Discriminant function 1 (CV1) explained 57.46 % of the variation among groups and was correlated most strongly with tarsus (a measure of skeletal size) followed by tail. CV2 explained a further 38.30 % and was strongly correlated with culmen. In general, birds from Rottnest Island are significantly larger in overall body size compared to east-coast colonies, however Raine Island birds have significantly longer culmens than elsewhere. Within colonies males are subtly larger than females, but relative to overall size, only bill morphology was significantly larger. A novel form of mate choice (disassortative) based on bill width was also observed at both Heron and Lord Howe Islands. Patterns of morphological variation and pair formation do not fit with those expected if environmental conditions alone (i.e. plasticity) are responsible. Instead, the results suggest that morphological diversity is more likely to involve selection. Finally, levels of gene flow were gauged and compared to morphological variation to determine if gene flow constrains morphological divergence among colonies. Three intron and three microsatellite loci were used. Gene flow estimates differed according to the type of marker. Introns suggest substantial inter-colony movement whereas microsatellites imply that gene flow is restricted. The different estimates reflect differences in the mutation rates of the two markers. Consequently, introns (evolving more slowly) likely reveal historical connections during the Pleistocene, with microsatellites representing more contemporary patterns. A lack of congruence between the amount of morphological and genetic differentiation suggests that genetic drift alone cannot explain all of the observed morphological diversity in wedge-tailed shearwaters. Taken together, the results from this study clearly suggest that oceanographic/environmental regimes have an important function in the development and maintenance of seabird diversity and can substantially influence the direction of micro-evolutionary change. This has important implications from a management perspective, as some colonies will need to be considered independently. Future work should focus on assessing the role of selection in causing the observed patterns by evaluating the relationship of behavioural, morphological and physiological (chick development) traits to fitness in alternative habitats.

Variation in egg-size in the Wedge-tailed Shearwater (Puffinus pacificus)

Abstract: We assessed variation in the size of eggs of Wedge-tailed Shearwaters (Puffinus pacificus) within and between two colonies in eastern Australia. Eggs at Heron Island were significantly larger than at Lord Howe Island. We also found significant between-season variation in size of eggs at Heron Island, with larger eggs being laid in 2005 than 2006. Mean female size (as indicated by tarsal length) did not differ between the two colonies, or between seasons at Heron Island. However, as with other seabird species, larger females produced larger eggs. Overall, our results imply that facultative changes in female reproductive effort associated with changes in availability of resources are not the main cause of variation in egg-size in this species. The consistently smaller size of eggs for birds at Lord Howe Island compared with those from Heron Island suggests that obligate processes (e.g. natural selection) are more likely to be responsible.

Predation of Eared Grebe by Great Blue Heron

Abstract: Great Blue Herons (Ardea herodias) typically prey upon fish and other aquatic organisms, and they occasionally take small mammals and birds. We observed a Great Blue Heron attack, kill, and attempt to consume an Eared Grebe (Podiceps nigricollis). The heron was unable to swallow the grebe, and it abandoned the carcass after approximately 30 min. An examination of the carcass showed that the grebe lacked obvious physical deformities. Our observation, coupled with a similar one nearby, indicates that Great Blue Herons attack and kill birds larger than reported previously.

Overstreetia olsoni n. sp. (Digenea: Zoogonidae) from the Capricorn silverside Atherinomorus capricornensis (Woodland) (Atherinidae) off Heron Island, southern Great Barrier Reef

Abstract: A new species, Overstreetia olsoni, is described from Atherinomorus capricornensis off Heron Island on the Great Barrier Reef off Queensland, Australia. It differs from its only known congener in that the enlarged spines of the circum-oral rows are smaller ( ≤ 4.5 × 3.5 vs ≤ 21.5 × 10.5μm), the sucker-ratio is smaller (1: 0.97–1.01 vs 1:1.8) and the eggs are larger (40–45 × 22–28 vs 34–37 × 17–22μm).

Diet of the black-headed heron Ardea melanocephala during the breeding season in South African grasslands

Abstract: The diet of the black-headed heron was studied using analysis of pellets and prey remnants (225 prey items identified) collected from four sites in South African Highveld Grassland, transformed into cultivated fields. Small vertebrates comprised the staple food of chicks. Rodents were the most important vertebrate prey. Otomys irroratus comprised ca. 50% of the total biomass of vertebrate prey consumed. The diet was supplemented by small lizards, snakes, frogs and fishes. Grasshoppers, beetles, crabs and other arthropods were occasionally preyed upon.

Time Budget of White-eared Night Heron in Captivity

Abstract: This paper presents some recent results on the time budget of white-eared night heron(Gorsachius magnificus) in captivity,an endangered species in the world.The observation by all-occurrences' recording method from October 2003 to April 2004 was conducted.The results are as follows: The time that white-eared night heron started to act at dark was changeable in different months.During the observation,the earliest starting time was 17∶07 pm on April 15th and the latest time was 18∶49 pm on February 3th.The major behaviors of the heron were standing,resting,moving,feeding,body caring and others(including excreting,drinking and calling).Daily time budget was: resting 82.48%,standing 8.64%,moving 5.36%,feeding 1.97%,body caring 1.30%,others 0.25%(Fig.3).Most of the time was occupied by resting and standing in a day.There were no significant differences in time budget among seasons.Standing,moving and body caring showed three peaks in a day,i.e.from 6∶30 to 9∶00 am,18∶00 to 21∶00 pm and 23∶00 pm to 1∶00 am.However,the exact time these activities occurred and lasted was different.Standing showed two peaks at night,i.e.from 19∶00 pm to 1∶00 am and 5∶00 am to 7∶00 am.Moving had three peaks which were from 17∶00 to 19∶00 pm,23∶00 to 1∶00 am and 5∶00 to 7∶00 am.Feeding mainly occurred from 19∶00 to 21∶00 pm and then decreased till dusk.Body caring occurred from 19∶00 to 21∶00 pm and 23∶00 to 1∶00 am.Resting was conversed to other activities(Fig.1).It might suggest that daily activities of white-eared night heron always occurred at dark,dusk and midnight. Analysis of variance showed that resting,standing,moving,feeding,body caring in different time of a day were different significantly(F=2.501～11.331,P0.01,df=107).

ÉXITO DE ANIDACIÓN DE LA GARZA REAL Egretta alba (Aves, Ardeidae) EN EL DEPARTAMENTO DE CÓRDOBA, COLOMBIA Nesting Success of the Great-White Heron (Egretta alba) in the Departament of Córdoba, Colombia

Abstract: Between July and November 2001, we evaluated the nesting success of the Great-white Heron (Egretta alba) during one breeding period at a shrimp pond in northeastern Colombia. We examined the relationship between nesting success and two nest variables: position within the colony (peripheral vs. central), and vertical location on sampled trees, finding a significant relationship between each pair of variables. Regression analysis showed a positive relation between nesting success and distance from the center of the mangrove. By the end of the nesting period, 52% of the nesting couples were successful, increasing the population size by 100%.