Sea and colonial-nesting birds of islands in the southern part of Amurskii Liman

The quantity of the nesting couples of sea birds on the islands of the southern part of Amurskii Liman was determined: common heron Ardea cinerea, slaty-backed gull Larus schistisagus, black-tailed gull L. crassirostris, and sooty guillemot Cepphus carbo.     

Vegetation development on the barrier islands of the Ola lagoon (the Sea of Okhotsk) in conditions of the rapidly increasing number of seabirds

Colonies of slaty-backed gull (Larus schistisagus) are studied on the barrier islands of the Ola lagoon (the Sea of Okhotsk), whose coastline has undergone significant changes for the last 40 years. The abundance of birds has grown by a factor of 2.5 for 5 years and reached 7000 pairs in 2014. Five vegetation communities with the prevalence of herbaceous plants are described and schemed.     

The effect of organochlorines and heavy metals on sex steroid-binding proteins in vitro in the plasma of nesting green turtles, Chelonia mydas

In this study on green turtles, Chelonia mydas, from Peninsular Malaysia, the effect of selected environmental toxicants was examined in vitro. Emphasis was placed on purported hormone-mimicking chemicals such as dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethylene, dieldrin, lead, zinc and copper. Five concentrations were used: high (1 mg/L), medium (10⁻¹ mg/L), low (10⁻² mg/L), very low (10⁻⁶ mg/L) and control (diluted carrier solvent but no toxicants). The results suggest that environmental pesticides and heavy metals may significantly alter the binding of steroids [i.e. testosterone (T) and oestradiol] to the plasma proteins in vitro. Competition studies showed that only Cu competed for binding sites with testosterone in the plasma collected from nesting C. mydas. Dieldrin and all heavy metals competed with oestradiol for binding sites. Furthermore, testosterone binding affinity was affected at various DDT concentrations and was hypothesised that DDT in vivo may act to inhibit steroid-protein interactions in nesting C. mydas. Although the precise molecular mechanism is yet to be described, DDT could have an effect upon the protein conformation thus affecting T binding (e.g. the T binding site on the steroid hormone binding protein molecule).     

Using flight initiation distance to evaluate responses of colonial‐nesting Great Egrets to the approach of an unmanned aerial vehicle

Remote‐controlled, unmanned aerial vehicles (UAVs) can be used to collect information in difficult‐to‐access places while potentially minimizing human disturbance. These devices have been widely used in a variety of ecological and behavioral studies in recent years, but additional study is needed to assess the magnitude of disturbance they cause to birds. We examined the responses of Great Egrets (Ardea alba) to a UAV in a breeding colony in Louisiana in 2016 where isolated patches of common reed (Phragmites australis) were used as nest sites by multiple breeding pairs. We examined the flush responses and flight initiation distances (FIDs) of nesting adults to the direct vertical approach of a UAV. Incubating adults were more likely to flush from nests and flushed at greater distances when approached by a UAV than adults with nestlings, suggesting that adult assessment of risk was based on the greater reproductive value of nestlings. We observed fewer flush responses and calculated lower set‐back distances using a UAV to approach nesting Great Egrets (~50 m) than set‐back distances calculated using traditional methods of approach (e.g., walking or boating; 87–251 m). We found that FIDs were shorter when more adults were present in nesting patches, suggesting that the perception of predation risk may be based in part on the reactions of other birds. Our results suggest that UAVs may be a useful alternative for monitoring colonial‐nesting waterbirds. However, our analyses were based exclusively on behavioral observations. Additional studies of the physiological responses of birds to the approach of UAVs are needed to better understand the stress responses of birds to these devices.     

Cape Delil-de-la-Kroiera (Sakhalin Island)—A new nesting point of marine birds

Two kekurs on Cape Delil-de-la-Kroiera (east coast of Sakhalin Island, to the north of Cape Ratmanova) were surveyed on July 16, 2003. Nesting of six species of sea birds was observed: slaty-backed gull (Larus schistisagus), black-legged kittiwake (Rissa tridactyla), common murre (Uria aalge), spectacled guillemot (Cepphus carbo), horned puffin (Fratercula corniculata), and tufted puffin (Lunda cirrhata).Original Russian Text Copyright © 2005 by Biologiya Morya, Blokhin, Tiunov.     

Island accessibility and distance from beach influence nesting success of Sooty Falcons Falco concolor in Oman

Colonial island‐breeding birds can be particularly vulnerable to anthropogenic disturbance, which can adversely affect their nesting success. We studied Sooty Falcons Falco concolor breeding on 10 ground‐predator‐free islands in the Sea of Oman during 2007–2014 and evaluated spatio‐temporal trends in the number of breeding pairs occurring on the islands and the factors influencing nesting success. The number of breeding pairs on the islands declined during the study, due mostly to the decline on accessible islands; the rate of decline on islands accessible to humans was double that on inaccessible ones. The number of nests with one or more eggs declined during the study period, and the percentage of nests with eggs that produced one or more chicks showed an increasing trend over time. Sooty Falcon nests located farther away from beaches experienced a significantly higher probability of nesting success than those located closer to beaches. Our results suggest that the number of breeding Sooty Falcons on the islands of northern Oman is declining and that human disturbance may be a contributing factor; this probably mirrors the situation in other parts of the breeding range of this species.     

Effects of Tamarix removal on the community dynamics of riparian birds in a semiarid grassland

Invasion of riparian habitats by non‐native plants is a global problem that requires an understanding of community‐level responses by native plants and animals. In the Great Plains, resource managers have initiated efforts to control the eastward incursion of Tamarix as a non‐native bottomland plant (Tamarix ramosissima) along the Cimarron River in southwestern Kansas, United States. To understand how native avifauna interact with non‐native plants, we studied the effects of Tamarix removal on riparian bird communities. We compared avian site occupancy of three foraging guilds, abundance of four nesting guilds, and assessed community dynamics with dynamic, multiseason occupancy models across three replicated treatments. Community parameters were estimated for Tamarix‐dominated sites (untreated), Tamarix‐removal sites (treated), and reference sites with native cottonwood sites (Populus deltoides). Estimates of initial occupancy (ψ₂₀₀₆) for the ground‐to‐shrub foraging guild tended to be highest at Tamarix‐dominated sites, while initial occupancy of the upper‐canopy foraging and mid‐canopy foraging guilds were highest in the treated and reference sites, respectively. Estimates of relative abundance for four nesting guilds indicated that the reference habitat supported the highest relative abundance of birds overall, although the untreated habitat had higher abundance of shrub‐nesters than treated or reference habitats. Riparian sites where invasive Tamarix is dominant in the Great Plains can provide nesting habitat for some native bird species, with avian abundance and diversity that are comparable to remnant riparian sites with native vegetation. Moreover, presence of some native vegetation in Tamarix‐dominated and Tamarix‐removal sites may increase abundance of riparian birds such as cavity‐nesters. Overall, our study demonstrates that Tamarix may substitute for native flora in providing nesting habitat for riparian birds at the eastern edge of its North American range.     

Development and regulation of heart rate in embryos and hatchlings of gulls (Larus schistisagus and Larus crassirostris) in relation to growth

We compared the developmental patterns of mean heart rate in Larus crassirostris and L. schistisagus embryos and chicks with other avian species of different hatchling developmental modes. We proposed that, since mean heart rate is inversely related to fresh egg mass in all birds, larger species reached a higher fraction of their hatchling mean heart rate by the end of the early phase of incubation and that heart rate contributions to supplying the increasing metabolic demands during mid and late incubation phases were less important than in smaller avian species. Mean heart rate was essentially independent of age throughout the mid-incubation phase (33% of normalised incubation until pipping), but increased with time during early (L. schistisagus only investigated) and late-incubation phases in both species. The O₂ pulse of L. schistisagus embryos and chicks increased linearly with yolk-free body mass (log-log) after the early-phase of incubation until shortly before pipping, but was independent of body mass in the periods before and after. We conclude that a high heart rate in this first period is probably more important for increasing the circulation of nutrients to the embryo at a stage when extra-embryonic circulation to the yolk sac is limited by the size of the growing area vaculosa. Furthermore, large increases in mean heart rate during the late-incubation phase are probably important for increasing the cardiac output to hatching levels with onset of endothermy. However, mean heart rate is stable over the mid-incubation while O₂ pulse increases, suggesting that increases in stroke volume and other circulatory adjustments may be entirely responsible for the largest increases in O₂ transport during incubation of large avian species. Accepted: 18 May 2000     

The birch tube-maker Acrobasis betulella in a fragmented habitat: the importance of patch isolation and edges

We examined the response of the birch tube-maker Acrobasis betulella Hulst (Lepidoptera: Pyralidae) to habitat patch isolation and edges. Density of A.␣betulella larva was higher on distant islands than on islands close to the shore. Following experimental removal of all larvae from the islands, adults were able to recolonize even the most distant islands, and larval density was again positively correlated with the degree of isolation. Larval density was not correlated with island size or the amount of birch present on the islands. Larvae on more distant islands did not have lower mortality than those in less isolated sites. Larvae were found more often on edges than in the interior of birch stands and developed faster on edges. This positive edge effect, coupled with the ability of the adults to disperse to even our most distant islands, suggests that A. betulella would be favored in an environment fragmented at the same scale as our island system. Received: 15 April 1996 / Accepted: 30 September 1996     

Health assessment of Black-crowned Night-herons (Nycticorax nycticorax) of the New York Harbor estuary

Blood samples from 145 Black-crowned Night-heron (Nycticorax nycticorax, BCNH) chicks (mean age 3 weeks) were taken from four island colonies (Goose (2004), Canarsie Pol (2005), Hoffman (2004 and 2005) and North Brother (2004 and 2005)) in New York Harbor in 2004 and 2005 to establish baseline health reference ranges for this species and to compare health indices of birds reared on different islands. Packed cell volume (PCV) and total solids (TS) did not differ among islands in either year. Herons raised on Hoffman Island in 2004 had lower white blood cell count (WBC), and higher activities of creatine phosphokinase (CPK), lactate dehydrogenase (LDH), aspartate amino transferase (AST), higher concentrations of potassium (K) and phosphorous (PHOS) and lower liver derived proteins (TP, prealbumin, albumin, alpha 1 globulins, alpha 2 globulins, beta globulins and gamma globulins) compared to herons from Goose and North Brother Islands. These changes suggest compromised health in chicks reared on Hoffman Island in 2004. On Hoffman in 2005, these biochemical analytes did not differ from concentrations and enzyme activities measured from birds on other islands. Although no single etiology can explain these extensive changes, it is likely that exposure to contaminants at foraging sites used by birds nesting on Hoffman and/or changes in prey availability and abundance causing birds to forage in different locations between years, led to differences measured in blood-based health indices. Avian health assessments coupled with foraging ecology serve as an excellent method for evaluating ecosystem health of the New York Harbor estuary system.     

Competitive abilities of oystercatchers ( Haematopus ostralegus ) occupying territories of different quality

In territorial species, habitat heterogeneity results in some individuals occupying poor quality sites while others occupy high quality sites. Floaters (mature nonbreeders) may accept a low quality territory, because it is the best they can get and defend (‘inferior phenotype hypothesis’), or because it is a strategic alternative for a high quality territory in the long run (‘queue hypothesis’). Oystercatcher Haematopus ostralegus territories differ consistently in the amount of offspring produced each year and this is related to the distance between the nesting and feeding territories. The inferior phenotype hypothesis was previously rejected on the basis of the absence of morphometric differences (assumed to indicate competitive abilities) among breeders. We investigated social dominance, in the field and in captivity, in relation to the quality of the breeding territory. In the field, birds with high-quality territories won more often compared to those occupying low-quality territories. However, this difference was not apparent in a small dataset of captive birds. These results are discussed in the framework of the long-term fitness prospects of settling in a high or low quality territory.     

Nesting habitat characteristics of Marbled Murrelets occurring in near‐shore waters of the Olympic Peninsula,Washington

Marbled Murrelets (Brachyramphus marmoratus) are listed as threatened in the portion of their range extending from British Columbia to California due to loss of nesting habitat. Recovery of Marbled Murrelet populations requires a better understanding of the characteristics of their nesting habitat in this part of their range. Our objective, therefore, was to describe their nesting habitat in Washington State and Vancouver Island, British Columbia. We captured Marbled Murrelets from 2004 to 2008, fitted them with radio transmitters, and followed them to nests (N = 20). We used Cohen's unbiased d effect size to assess differences between forest plots surrounding nest sites and nearby control sites (N = 18). Nest sites had less canopy cover of the dominant conifers and fewer, but larger, trees than control sites. Nest sites also had greater percentages of trees with platforms >10 cm diameter and >15 cm diameter, and more platforms of these sizes than control sites. The mean diameter at breast height of nest trees was 136.5 cm (range = 84–248 cm) and all but one nest was in dominant or co‐dominant tree species. At the landscape scale, we used vegetation maps derived from remotely sensed data and found greater canopy cover, higher density of mature trees, more platforms >10 cm/ha, and more old‐growth habitat at nest sites than at random sites. Our findings suggest that, at the site scale, nesting Marbled Murrelets selected the most suitable features of forest structure across expansive potentially suitable habitat. Our landscape‐scale analysis showed that habitat features in nesting stands differed from those features in available stands in the murrelet's range in Washington. We also found that stands with nests were less fragmented than available forest across murrelet range. All nest sites of radio‐tagged birds in Washington were in protected areas in mostly undisturbed forest habitat. Conservation of these areas of inland nesting habitat will be critical to the recovery of Marbled Murrelet populations.     

Compounding effects of habitat fragmentation and predation on bird nests

Habitat fragmentation and invasive species are two of the greatest threats to species diversity worldwide. This is particularly relevant for oceanic islands with vulnerable endemics. Here, we examine how habitat fragmentation influences nest predation by Rattus spp. on cup‐nesting birds in Samoan forests. We determined models for predicting predation rates by Rattus on artificial nests at two scales: (i) the position of the bird's nest within the landscape (e.g. proximity to mixed crop plantations, distance to forest edge); and (ii) the microhabitat in the immediate vicinity of the nest (e.g. nest height, ground cover, slope). Nest cameras showed only one mammal predator, the black rat (Rattus rattus), predating artificial nests. The optimal model predicting nest predation rates by black rats included a landscape variable, proximity to plantations and a local nest site variable, the percentage of low (<15 cm) ground cover surrounding the nest tree. Predation rates were 22 ± 13% higher for nests in forest edges near mixed crop plantations than in edges without plantations. In contrast, predation rates did not vary significantly between edge habitat where the matrix did not contain plantations, and interior forest sites (>1 km from the edge). As ground cover reduced, nest predation rates increased. Waxtags containing either coconut or peanut butter were used as a second method for assessing nest predation. The rates at which these were chewed followed patterns similar to the predation of the artificial nests. Rural development in Samoa will increase the proportion of forest edge near plantations. Our results suggest that this will increase the proportion of forest birds that experience nest predation from black rats. Further research is required to determine if rat control is needed to maintain even interior forest sites populations of predator‐sensitive bird species on South Pacific islands.     

Temporal patterns of occurrence and transmission of the blood parasite Haemoproteus payevskyi in the great reed warbler Acrocephalus arundinaceus

We studied the prevalence and intensity of the haemosporidian blood parasite Haemoproteus payevskyi in great reed warblers at Lake Kvismaren (6 years) and Lake Segersj? (3 years) in Sweden. Based on microscopic inspection of slides from 282 adult birds, 20.6% showed infection of H. payevskyi in circulating red blood cells in at least 1 year. For parasite prevalence, there was no difference between years, sex, and age classes. However, parasite intensity was higher in females than in males, and this was most pronounced in 1-year-old birds. Individuals scored to carry parasites in year _n were more likely to show parasite infection year _n + 1 than birds scored to be parasite-free in year _n . None of 99 juvenile birds examined at the breeding site in late summer, 4–9 weeks after hatching, showed infection of H. payevskyi. Parasite intensity in infected adult birds decreased in the course of the breeding season and no new or relapse infections were observed during this period. Thus, our data imply that in the great reed warbler, a long-distance migrant to tropical Africa, transmission of H. payevskyi occurs on wintering sites or at stopover sites during migration.     

PARTITIONING OF NESTING SPACE AMONG SEABIRDS OF THE BENGUELA UPWELLING REGION

Duffy, D. C. & La Cock, G. D. 1985. Partitioning of nesting space among seabirds of the Benguela upwelling region. Ostrich 56:186-201.

An examination of nesting habitats used by the four main species of seabirds nesting on southern African islands (Jackass Penguin Spheniscus demersus, Cape Cormorant Phalacrocorax capensis, Bank Cormorant P. neglectus and Cape Gannet Morus capensis) revealed relatively minor differences and extensive overlaps between species, primarily in subcolony size, steepness of nesting substratum, and proximity to cliffs. A weak dominance hierarchy existed; gannets could displace penguins, and penguins could displace cormorants. This hierarchy appeared to have little effect on partitioning of nesting space. Species successfully defended occupied sites in most cases of interspecific conflict, suggesting that site tenure by one species could prevent nesting by another. The creation of additional nesting space on Namibian nesting platforms did not increase guano harvests, suggesting that nesting space had not previously limited the total nesting population of Cape Cormorants, the most abundant of the breeding species, in Namibia.

While local shortages of nesting space may occur, populations of the four principal species of nesting seabirds in the Benguela upwelling region do not seem to have been limited by the availability of nesting space on islands.     

Exponential population increase in the endangered Ouvéa Parakeet (Eunymphicus uvaeensis) after community-based protection from nest poaching

The Ouvéa Parakeet (Eunymphicus uvaeensis), endemic to Ouvéa Island (Loyalty Islands, New Caledonia, south-west Pacific), is a rainforest bird that is dependent on tree cavities for nesting. It is threatened by deforestation, but also by competition for nest sites with introduced bees, harvesting for pets, and potentially predation by introduced species. Despite these threats, we show that the Ouvéa Parakeet population increased exponentially from an estimated 617 (274–996) birds in 1993 to 2,090 (1,280–3,413) birds in 2009 (95% confidence interval). We explain this population increase by community-based protection measures that eliminated nest poaching. We recommend that these measures are maintained, remnant forest is protected, and the introduction of rats is prevented.     

Plants and birds on the shore of the Sea of Okhotsk: Balance, crisis, adaptation

Mutual relationships between sea colonial birds and plants on the northern shore of the Sea of Okhotsk are considered. The birds form huge flocks on small islands thus transforming the island landscape and providing specific vegetation at nesting sites. The intensity of ornithogenic load determines different relations between the productivity of plant communities and their species richness. As a rule, flora is depleted. The plants thriving at rookeries react to the intensive action of birds by forming specific ecobiomorphs. On the islands of the northern part of the Sea of Okhotsk tussocks of pine purple grass existing on the majority of nesting colonies are of the highest significance.     

Evidence of olive ridley mitochondrial genome introgression into loggerhead turtle rookeries of Sergipe, Brazil

The coastline of Sergipe state hosts the main Brazilian nesting sites of Lepidochelys olivacea (Eschscholtz, 1829). The second most abundant species of turtles in Sergipe is Caretta caretta (Linnaeus, 1758). Both sea turtle species, respectively known as olive ridley and loggerhead, are currently listed as endangered by the International Union for the Conservation of Nature and Natural Resources. The genetic diversity of the Sergipe loggerhead population (N = 51) was assayed by analyzing 627 bp from the control region of mitochondrial DNA in nesting females. Three haplotypes were identified: CC-A4, CC-A24 and CC × LO. The last one was recorded for specimens considered hybrids because they represent L. olivacea’s mtDNA, but had the external morphology of C. caretta or of a mixture of both species. Based on the two types of hybrids, it was hypothesized that at least two hybridization events had occurred: a more ancient hybridization event, accompanied by introgression (F2 or later backcrosses), and a recent one (F1), both of which involving the same L. olivacea haplotype. The incidence of L. olivacea mitochondrial genome introgression into the C. caretta rookeries was only observed in Sergipe, which could be related to the large numbers of L. olivacea in this region and an overlap of reproduction periods and distribution areas of both species. This may also be associated to global warming since it might alter the sex ratio of sea turtles, thus facilitating interspecific mating. Awareness of gene flow between these species will significantly influence the development and implementation of adequate management strategies.     

The genetic structure of the loggerhead sea turtle (Caretta caretta) in the Mediterranean as revealed by nuclear and mitochondrial DNA and its conservation implications

The population genetic structure of the loggerhead sea turtle (Caretta caretta) nesting in the eastern Mediterranean was assessed by sequencing a fragment of the control region of the mitochondrial DNA (n = 190) and seven microsatellites (n = 112). The two types of markers revealed genetic structuring (mtDNA: γ_st = 0.212, P < 0.001; nDNA F _st = 0.006, P < 0.001), thus indicating that both females and males are philopatric and that gene flow between populations is restricted. Mitochondrial DNA data indicate that the female populations nesting on the islands of Crete and Cyprus have suffered a recent bottleneck or colonization event. However, no bottleneck or founder effect was revealed by nuclear markers, thus indicating male-mediated gene flow from other populations that would increase nuclear genetic variability. Crete, and to a lower extent Cyprus, are thought to play a central role in such male-mediated gene flow that may reduce the negative effect of genetic drift or inbreeding on the small populations of Lebanon and Israel. This population structure indicates that assessing population relevance only on the basis of genetic variability and size would be misleading, as some populations not fulfilling those requirements may play a relevant role in genetic exchange and hence contribute to the overall genetic variability.     

Nesting Ecology of Boreal Forest Birds Following a Massive Outbreak of Spruce Beetles

Abstract: We studied breeding dark-eyed juncos (Junco hyemalis), yellow-rumped warblers (Dendroica coronata), and spruce-nesting birds from 1997 to 1998 among forests with different levels of spruce (Picea spp.) mortality following an outbreak of spruce beetles (Dendroctonus rufipennis) in Alaska, USA. We identified species using live and beetle-killed spruce for nest sites and monitored nests to determine how the outbreak influenced avian habitat selection and reproduction. We tested predictions that 1) nesting success of ground-nesting juncos would increase with spruce mortality due to proliferation of understory vegetation available to conceal nests from predators, 2) nesting success of canopy-nesting warblers would decrease with spruce mortality due to fewer live spruce in which to conceal nests, and 3) both species would alter nest-site selection in response to disturbance. Juncos did not benefit from changes in understory vegetation; nesting success in highly disturbed stands (46%) was comparable to that in undisturbed habitats throughout their range. In stands with low spruce mortality, nesting success of juncos was low (5%) and corresponded with high densities of red squirrels (Tamiasciurus hudsonicus). Yellow-rumped warblers nested exclusively in spruce, but success did not vary with spruce mortality. As disturbance increased, nesting warblers switched from selecting forest patches with high densities of live white spruce (Picea glauca) to patches with beetle-killed spruce. Warblers also placed nests in large-diameter live or beetle-killed spruce, depending on which was more abundant in the stand, with no differences in nesting success. Five of the 12 other species of spruce-nesting birds also used beetle-killed spruce as nest sites. Because beetle-killed spruce can remain standing for >50 years, even highly disturbed stands provide an important breeding resource for boreal forest birds. We recommend that boreal forest managers preserve uncut blocks of infested forest within managed forest landscapes and practice partial harvest of beetle-killed spruce rather than commercial clear-cutting of infested stands in order to sustain breeding bird populations until natural reforestation occurs. Because breeding densities do not always reflect fitness, assessing impacts of a massive natural disturbance should include measuring impacts of changes in vegetation on both reproductive success and predator-prey dynamics.