Podiceps Nigricollis Research Articles

Waterbird community changes in the Wilderness Lakes, South Africa (Part 3 of 3): Diving piscivores and scavengers

Estuarine waterbodies typically support diverse and abundant waterbird communities. However, global environmental degradation as a result of anthropogenic activities is leading to species level changes in biodiversity, with top predators such as piscivorous waterbirds being particularly vulnerable to ecosystem changes. The study aimed to document long-term spatial and temporal patterns of abundance of piscivorous and scavenging waterbirds in the Wilderness Lakes Complex (WLC) in the Garden Route National Park, South Africa, and where possible identify potential causes for observed trends. The abundance of waterbirds on these wetlands was determined biannually from 1992 to 2019, with counts conducted from a boat following a standardised route. Historical waterbird abundance data from the 1980s were also used to describe long-term abundance changes. Eight of the species exhibited seasonal variability in abundance with most, excluding Common Tern Sterna hirundo, being more abundant in winter. Substantial changes occurred in the abundance of several species over the four-decade study period, notably increases in Cape Cormorant Phalacrocorax capensis and Great Crested Grebe Podiceps cristatus, and decreases in Common Tern and Black-necked Grebe Podiceps nigricollis. Long-term abundance trends indicate a combination of declining, increasing, and stable populations. Although some species have undergone contrasting abundance changes on different waterbodies in the WLC the dominant pattern was a similar direction of change on most or all waterbodies and in different seasons. Local reasons for changes probably include loss of sandbanks, changing prey availability, and the absence of recreational disturbance on some waterbodies.Conservation implications: Drivers of changes in the abundances of piscivores are likely to be multifaceted, functioning on multiple spatial and temporal scales, and affecting different species in different ways. Recommended local corrective actions include managing emergent macrophyte encroachment on sandbanks, reducing recreational disturbance, managing processes affecting indigenous fish stocks, and protecting nesting sites.

Comparative analysis of the gut bacteria of the relict gull (Larus Relictus) and black-necked grebe (Podiceps Nigricollis) in Erdos Relic Gull National Nature Reserve in Inner Mongolia, China.

The gut microbiota promotes host health by maintaining homeostasis and enhancing digestive efficiency. The gut microflora in wild birds affects host physiological characteristics, nutritional status, and stress response. The relict gull (Larus Relictus, a Chinese national first-class protected species) and the black-necked grebe (Podiceps Nigricollis, a secondary protected species) bred in the Ordos Relic Gull National Nature Reserve share similar feeding habits and living environments but are distantly related genetically. To explore the composition and differences in the gut microbiota of these two key protected avian species in Erdos Relic Gull National Nature Reserve and provide a basis for their protection, 16S rRNA gene high-throughput sequencing was performed and the gut microbial diversity and composition of the relict gull (L. Relictus) and black-necked grebe (P. Nigricollis) was characterized. In total, 445 OTUs (operational taxonomic units) were identified and classified into 15 phyla, 22 classes, 64 orders, 126 families, and 249 genera. Alpha diversity analysis indicates that the gut microbial richness of the relict gull is significantly lower than that of the black-necked grebe. Gut microbe composition differs significantly between the two species. The most abundant bacterial phyla in these samples were Proteobacteria, Firmicutes, Fusobacteria, and Bacteroidetes. The prominent phylum in the relict gull was Proteobacteria, whereas the prominent phylum in the black-necked grebe was Firmicutes. The average relative abundance of the 17 genera identified was greater than 1%. The dominant genus in the relict gull was Escherichia-Shigella, whereas Halomonas was dominant in the black-necked grebe. Microbial functional analyses indicate that environmental factors exert a greater impact on relict gulls than on black-necked grebes. Compared with the relict gull, the black-necked grebe was able to use food more efficiently to accumulate its nutrient requirements, and the gut of the relict gull harbored more pathogenic bacteria, which may be one reason for the decline in the relict gull population, rendering it an endangered species. This analysis of the gut microbial composition of these two wild avian species in the same breeding grounds is of great significance, offers important guidance for the protection of these two birds, especially relict gulls, and provides a basis for understanding the propagation of related diseases.

Viability and hatchability of brine shrimp Artemia franciscana cysts after passing through the digestive system of eared grebes Podiceps nigricollis

Viability and hatchability of brine shrimp Artemia franciscana cysts after passing through the digestive system of eared grebes Podiceps nigricollis

Mangcuo Lake in Hengduan Mountains: An Important Alpine Breeding and Stopover Site along Central Asian Flyway

The stopovers provide food and habitat for migratory birds and therefore play an important role in facilitating the birds' completion of their migration. The Hengduan Mountains, which have a complex topography, are located in a large corridor of the Central Asian migratory flyway, so the lakes along the Hengduan Mountains are important for waterbird migration. The existing research on lakes in the Hengduan Mountain area is mostly concentrated in the central and southern parts of the mountains, which proves that many lakes are wintering grounds for migrating birds. We wonder whether the ecological functions of lakes will change more with further elevation. With this question, we conducted four surveys for the seasonal bird survey in Mangcuo Lake, which is located in the northwest of the Hengduan Mountains, in Markam County of Qamdo City, between October 2019 and July 2020. We recorded a total of 6109 birds from 20 species of waterbirds, including 20 species of migratory waterbirds, accounting for 100% of all bird species. The diversity and richness of waterbirds in Mangtso Lake is shown as spring > autumn ≥, summer > winter, with no waterbirds in winter. The black-necked grebe (Podiceps nigricollis), great crested grebe (Podiceps cristatus), bar-headed goose (Anser indicus), and ruddy shelduck (Tadorna ferruginea) were the dominant species in the waterbird community. The highest number of waterbird species and total individuals were found in the transition zone between the marsh wetlands and lakes, and the number of waterbird species differed significantly among habitats (X2 = 14.405, p = 0.000), with habitat complexity being an important factor influencing waterfowl abundance and distribution. The IUCN Red-listed species recorded include the black-necked crane (Grus nigricollis), painted stork (Mycteria leucocephala), and common pochard (Aythya ferina). By comparing with other lakes in Hengduan Mountain, we found that the ecological functions of the plateau lakes in the Hengduan Mountains, to support the life histories of migrating waterbirds, are gradually transforming as the altitude rises, and can be divided into approximately three levels, with the first level of Qionghai, Chenghai, Erhai, and Jianhu at altitudes of 1500-2200 m being the most important ecological function in terms of providing wintering grounds for migrating birds. The second layer, at an altitude of 2400-3300 m, includes Lashihai, Lugu Lake, and Napahai, which are not only wintering wetlands for migratory birds but also important stopover sites. The third layer of Mangcuo Lake, which is above 4000 m above sea level, provides a breeding ground for some migratory waterbirds in summer and a migratory resting place for migratory waterbirds in spring and autumn. We advocate for the importance of Mangcuo Lake in the alpine region along the central Asian flyway, as well as emerging nature conservation action that was previously neglected.

Emerging Highly Pathogenic Avian Influenza (H5N8) Virus in Podiceps nigricollis in Northwest China in 2021

Three highly pathogenic avian influenza (H5N8) viruses were detected in the migratory bird Podiceps nigricollis in Northwest China in June 2021. Phylogenetic analysis indicated that these H5N8 isolates belonged to clade 2.3.4.4b, which were highly homologous to strains isolated in China and South Korea. In this study, H5N8 virus infection in Podiceps nigricollis was detected using Oxford Nanopore Technologies sequencing technology and caused pathological changes in multiple organs.

Factors Affecting Colony Size and Breeding Parameters of Eared Grebe (Podiceps nigricollis) in Carp Ponds

Understanding important factors for breeding Eared Grebes (Podiceps nigricollis) is essential for its conservation. We aimed to study the impact of some factors on nests and breeding success in this species in fishponds (S Poland). Number of Eared Grebe nests were counted on particular carp ponds. Pond size, vegetation cover, number of nests in colonies of associated gull or tern species, and age of stocked common carp (Cyprinus carpio) were determined for all ponds with nests. We also investigated the relationship between nest size, material used to construct them and clutch size. Number of Eared Grebe nests positively correlated with number of breeding pairs of associated colonial species (terns or gulls). Selection of the breeding site by the Eared Grebe can be explained by appropriate nest protection by large colonies of associated species (Whiskered Tern Chlidonias hybrida and Black-headed Gull Chroicocephalus ridibundus). Nest size was not related to clutch size. A negative relationship between breeding success and number of nests of Eared Grebe was found. Food is a not limiting factor for the Eared Grebe on fishponds with extensive production, and presumably other factors such as weather conditions may explain the low breeding success of this species.

Morphology of Streptocara crassicauda and S. recta, with a Review of the Genus Streptocara (Nematoda: Acuariidae) and an Identification Key to Its Species

The cosmopolitan genus Streptocara Railliet, Henry and Sisoff, 1912 (Nematoda: Acuariidae) comprises parasites of the upper alimentary tract of aquatic and, rarely, terrestrial birds. Two species of the genus Streptocara are redescribed from Bulgaria by means of light and scanning electron microscopy: Streptocara crassicauda (Creplin, 1829), based on specimens from Larus genei, Larus minutus (Laridae) and Aythya ferina (Anatidae), and Streptocara recta (von Linstow, 1879) from Podiceps nigricollis (Podicipedidae). This is the first record of S. recta from Bulgaria. The host and distribution records of the species of the genus Streptocara are reviewed. Six species are recognised as valid. Streptocara crassicauda (Creplin, 1829), S. californica (Gedoelst, 1919), S. formosensis Sugimoto, 1930 and S. incognita Gibson, 1968, seem to be parasites well-adapted to birds of the family Anatidae (Anseriformes) and occasionally found in other birds, whereas S. recta (von Linstow, 1879) and S. longispiculata Gibson, 1968, are specialists of Podicipediformes and Gaviiformes, respectively. Streptocara indica Fotedar and Chishti, 1974, is recognised as a junior synonym of S. crassicauda, and Schistogendra oligopapillata Zhang and An, 2002, is considered as a junior synonym of Streptocara formosensis Sugimoto, 1930. An identification key to the species of the genus Streptocara is proposed.

Physiological strategies of moult-migrating Black-necked Grebes (Podiceps nigricollis) in a polluted staging site according to blood chemistry

After breeding, Black-necked Grebes (Podiceps nigricollis) perform a moult-migration to autumn hypersaline staging sites, where they moult the flight feathers and forage on superabundant brine shrimp (Artemia spp.) before leaving for wintering areas. During the stay in moulting sites, the grebes experience changes in organs and muscle size (atrophy, hypertrophy), and almost double their body mass, which has been suggested to act as an insurance against a collapse in prey availability in late autumn. During two years we collected blood samples from hundreds of individuals at one of the most important European moulting sites (the Odiel marshes, SW Spain), which is a highly polluted area due to mining drainage and chemical industry. We assessed the potential effect of moulting stage, day of the year and body condition on 16 blood biochemical parameters. Because of the changes in prey availability and body composition of grebes, we expected some physiological adjustments during moult. Elevated levels of cholesterol suggested that birds in active moult increased foraging effort to face the costs of moulting. There was increased amount of lactate dehydrogenase, corresponding to periods of breast muscle atrophy. Birds in active moult augmented protein ingestion, likely to account for the requirements of feather growth. We also show that the probability of fasting due to low prey availability increased late in the moulting season, as demonstrated by an increase in plasma β-hydroxy-butyrate.

Avian ecological status in the Gadaïne eco-complex (Batna, NE Algeria)

Wetlands represent ecosystems of great importance through their ecological and socio-economic functions and biological diversity, even if they are most threatened by anthropization. This study aimed to contribute to the creation of an inventory of bird species in the Gadaïne eco-complex (Batna, Algeria) from 2019 to 2021. Counts were carried out from 8:00 to 19:00 using a telescope (20 × 60) and a pair of binoculars (10 × 50) and by employing absolute and relative methods. Birds were categorized by phenology, habitat, biogeography, and diet. A total of 80 species in 58 genera and 19 families were observed. Migratory birds were dominant (38%) phenologically, and the birds of Palearctic origin dominated (26.25%) biogeographically. Invertivorous and carnivorous species were most common (35%). Ecologically, the majority of species were waterbirds (73.75%), which are protected in Algeria. This study highlights the need for the preservation of ecosystem components and enhancement of biological resources of protected, rare, and key species. We observed 43797 individuals of Marmaronetta angustirostris during our study and reported the nesting of Podiceps nigricollis, Porphyrio porphyrio, and Tadorna ferruginea. For this reason, it is recommended to propose the area as a Ramsar site.

Ecological aspects of the nesting life of the black-necked grebe (<i>Podiceps nigricollis</i> C.L. Brehm) in the forest-steppe zone of the Trans-Urals

The black-necked grebe (Podiceps nigricollis C.L. Brehm) is a nesting, migratory bird species, the number of which in the Southern Urals reaches 12 thousand individuals. From an ecological point of view, the named bird species belongs to aquatic birds and prefers aquatic and semiaquatic habitats. Being a waterfowl, the black-necked grebe has a complex of diving adaptations and is characterized as a specialized waterfowl. The literature analysis has proved that the knowledge of the ecological aspects of the nesting life of the black-necked grebe is insufficient. The nesting period of the annual life cycle was studied on the Kurlady and Smolino lakes located in the forest-steppe zone of the Trans-Urals. The average date of birds arrival at the nesting area according to 19882013 data is 19 April. The choice of breeding site leads to the fact that black-necked grebes form colonies in stagnant water bodies or with a slow flow of water. The water is fresh or brackish, with a certain pattern of overgrowth of vegetation and depth in the area where the nests are located. The presence of nests of black-headed gulls (Larus ridibundus L.) plays a special role in choosing a place to build a nest. Black-necked grebes and black-headed gulls form polyspecific colonial settlements. The laying of the first egg is carried out by the black-necked grebe in an unfinished nest, floating on the water and having a flat shape. At the stage of the appearance of the first egg in the nest, the elimination of eggs occurs, which can reach 44,1% (the biological center of the colony, 1989). On the periphery of the colonial settlement, the percentage of dead clutches is significantly higher, which can be caused by unfavorable biotic and abiotic relationships. Nests of black-necked grebes are completed from the moment the first egg is laid until the laying is completed. At a statistically significant level, the diameter of the nest and tray, the height of the nest, and the depth of the tray increase. The nest with completed masonry has a truncated-conical shape with a cup-shaped tray. According to long-term observations, the average value of the completed clutch is 3,8 eggs per nest. The reproduction in the composition of a polyspecific colony is accompanied by the establishment of biocoenotic relationships. The manifestation of topical, phoric and factory relationships, which can lead to individual and group elimination, has been established.

Abundance, Distribution and Migration Patterns of North American Eared Grebes (Podiceps nigricollis)

Most North American Eared Grebes (Podiceps nigricollis) undertake a post-breeding migration to two hypersaline lakes in the USA: Mono Lake in California and Great Salt Lake in Utah. Single air photo surveys were conducted in mid-October at Mono Lake from 1996-2012 and multiple fall surveys were conducted from 2013-2018, the latter to determine variation in abundance patterns within and across years. In four of the six years with multiple fall surveys, peak abundance occurred in mid-October as expected. However, in 2014 and 2015, Eared Grebe numbers declined dramatically soon after arrival, coinciding with low levels of their primary food, brine shrimp (Artemia monica). Abundance remained low from 2016-2018, and this could have been due to a shift to Great Salt Lake or to a massive mortality event. In 2017 and 2018, Eared Grebes breeding in south-central British Columbia, Canada were marked with Very High Frequency (VHF) radio transmitters and light-level geolocator (GLS) tags. Contrary to 1996, when the majority of VHF-tagged birds were molting/staging on Mono Lake, our 2017-2018 telemetry data indicated that most individuals were on Great Salt Lake. Our study provides insight into the variable abundance patterns at Mono Lake and novel information on Eared Grebe migration patterns.

A PRÉCIS AND CHECKLIST OF HELMINTH PARASITES FOR 14 SPECIES OF WATERFOWL FROM THE CHIHUAHUA DESERT IN THE UNITED STATES AND MEXICO.

A précis of helminth parasite infections and a host-parasite checklist are presented for the following 14 species of waterfowl from the Chihuahua Desert in the United States and Mexico: Chen rossii, Chen caerulescens, Anas platyrhynchos, Anas diazi, Anas acuta, Anas strepera, Anas americana, Anas clypeata, Anas cyanoptera, Anas crecca, Bucephala albeola, Oxyura jamaicensis, Fulica americana, and Podiceps nigricollis. There was a total of 127 species of helminths recovered from the 14 species of waterfowl. Total abundance, which included data available for 12 species of waterfowl, was 134,202 (mean = 11,184, median = 1,376, and 95% confidence limit [CL] = 14,485). Mean species richness ranged from 1.5 in Ross's goose, C. rossii, to 4.3 in the bufflehead, B. albeola. Host mean abundance ranged from 7.5 in the Mexican duck, A. diazi, and green-winged teal, A. crecca, to a high of 811 for the ruddy duck, O. jamaicensis. Ninety-one percent of the helminth species were generalists. Most specialists were associated with the American coot, F. americana (7), and the eared grebe, P. nigricollis (5). Percent helminth species contribution was cestodes 45%, nematodes 25%, trematodes 22%, and acanthocephalans 8%. The most commonly occurring helminth species among the 14 host species were the trematode Notocotylus attenuatus (12), the cestode Cloacotaenia megalops (10), the acanthocephalan Corynosoma constrictum (9), and the nematode Capillaria anatis (6). Low ingestion of invertebrates may have contributed to the lower number of helminth species and abundance in wintering and spring dabbling ducks (Anatini). Wild dabbling ducks ranging in age from 6 mo to 8 yr and 8 mo were infected with helminth parasites. Helminth parasite data from resident and nesting hosts and pre-fledged young birds indicated as many as 43 helminth life cycles may be occurring in the Chihuahua Desert. Host-parasite species checklists are included.

Nesting Status and Chronology of Eared Grebes Along Great Salt Lake, Utah

ABSTRACTEared grebes (Podiceps nigricollis) are colonial‐nesting waterbirds that breed in Canada and northern United States. Great Salt Lake (GSL), Utah, is vital to the survival of this species because all eared grebes in North America stage in the fall either on the GSL or Mono Lake, California. The importance of GSL and its surrounding wetlands for breeding eared grebes is unknown. We studied eared grebe nesting status and chronology in the freshwater wetlands around GSL and found over 4,280 nests distributed among 35 colonies during 2018 and 5,794 nests among 23 colonies during 2019. We also located the 2 largest colonies of this species ever recorded (902 and 1,492 nests). Mean clutch size differed between years and was 2.4 eggs during 2018 and 2.0 during 2019; clutch sizes were lower at GSL than in colonies located in more northern latitudes, perhaps due to a local paucity of invertebrate prey during the egg‐laying period. Grebe nests around the GSL were constructed with, and anchored to, growing Stuckenia pectinate. Eared grebes near GSL started laying eggs in the first week of June during 2018 and a week later during 2019. The number of incubated nests per colony peaked on 27 June during 2018 and 9 July during 2019. Nests continued to be incubated into August in both years. These dates are later than those reported in more‐northern colonies. The later nesting in GSL colonies could be due to the birds' need to wait for Stuckenia pectinata to form mats at the water surface. This plant species needs a water depth of 38 to 45 cm to thrive, and increasing amounts of freshwater from the GSL watershed are diverted for agriculture and human development. If this trend continues, there may not be enough water to maintain the required water depth for dense stands of Stuckenia; the loss of which may prevent the grebes from nesting. © 2021 The Wildlife Society.

General characteristics of the intensity of elimination in the early ontogenesis of colonial bird species

This paper examines the rate of elimination in the early ontogeny of colonial bird species. The research objects were colonial nesting species black-necked gull (Larus ridibundus L.) and black-necked grebe (Podiceps nigricollis C.L. Brehm), which form monospecific and poly-species colonial settlements. The rate of elimination was determined taking into account the stage of completion of the clutch, as well as the position of the nest in the structure of the colonial settlement: in the biological center or at the periphery of the colony. The nesting life of colonially nesting species was studied according to the generally accepted method, taking into account the choice of a place for building a nest by birds, the morphology of the nest, the intensity of oviposition and other characteristics. In the course of many years of research 3 types of nest placement within the colony have been identified. The maximum elimination rate has been proven for fixing the nest on the floodplain of common reed. The minimum rate of elimination was found for black-headed gull nests built on the fold of common reed (Phragmites australis) and narrow-leaved cattail (Typha angustifolia). Near-nesting vegetation is located around the nests of black-necked gull and black-necked grebe. The variant of placing vegetation around the nest prevails. Less common are options in which vegetation is located on one side. Observations have not revealed a relationship between the rate of elimination and the nature of the distribution of vegetation around the nest. The authors have compared the rate of elimination of black-headed gull nests located in the biological center and at the periphery of the colony. Elimination is possible both during the laying of the first egg and after the end of the clutch. Observations have shown that the rate of elimination is higher for nests from the periphery of the colony, which may be associated with differences in the size of the nests, the rate of their construction, as well as with the behavior of birds incubating eggs. The maximum rate of elimination of nests and eggs at the periphery of the colony is also manifested in the early ontogenesis of the black-necked grebe. The intensity of elimination and the forms of its manifestation affect the structure of the colonial settlement of birds and characterize the level of individual and group adaptation of birds to the conditions in which the nesting period takes place.

Mid-Late Pleistocene Neanderthal landscapes in southern Italy: Paleoecological contributions of the avian assemblage from Grotta del Cavallo, Apulia, southern Italy

We present a detailed paleoecologic analysis of avian assemblages from the Mousterian layers of the Middle Paleolithic Grotta del Cavallo site in southern Italy. Findings improve knowledge of the landscape that was exploited by Neanderthals. During the MIS 7, 6 and 3, the cave was surrounded by extensive grasslands and shrublands, locally interspersed by open woodland and rocky outcrops, whereas the coastal plain (currently underwater) hosted wetlands. Water bird taxa show an increase in population size during the cool-temperate climatic interval attributed to MIS 3, possibly linked to more humid conditions or a shorter distance between the wetland settings and the cave, compared to the previous glacial phase (MIS 6). In addition, coverage-based rarefied richness suggests higher avian diversity during MIS 3, which may reflect greater landscape heterogeneity due to the presence of wetland habitats. The tentative discovery of Branta leucopsis, together with several bird species currently found at higher altitudes, reinforces geochemically-derived palaeoclimate inferences of cooler than the present conditions. These assemblages also include the first fossil occurrence of Larus genei worldwide, the first Italian occurrence of Emberiza calandra, the oldest Italian occurrence of Podiceps nigricollis, and the occurrence of the rarely reported Sylvia cf. communis. Taphonomic analyses indicate that bone modifications are mainly due to physical syn- and post-depositional processes, and that the assemblage mainly accumulated through short-range physical transport and the feeding activities of nocturnal raptors.

Habitat selection by nesting Eared Grebes (Podiceps nigricollis) along Great Salt Lake, Utah

Eared Grebes (Podiceps nigricollis) are colonial-nesting waterbirds that use waterbodies along Great Salt Lake (GSL), Utah, during the breeding season. We examined the habitat characteristics of nesting colonies established by Eared Grebes, including water depth, invertebrate biomass density, vegetation species, vegetation cover, waterbody area, distance to shore, distance to nearest emergent vegetation, and distance to GSL. Samples and measurements were taken during the summer of 2018 from inside Eared Grebe nesting colonies, outside colonies but within the same waterbody, and unused waterbodies that did not contain colonies. We compared colonies sites to non-colonies sites that were within the same waterbody using logistic regression to build models and found no differences between them, suggesting that space for a colony is not lacking within a colony waterbody. Colony waterbodies differed from unused waterbodies (those not containing a colony) in having deeper water and higher percent cover of submerged aquatic vegetation. Results from Eared Grebe colonies around GSL were compared to colonies found in a literature review. Water depth in colonies around GSL were shallower than colonies located elsewhere. All of the colonies in this study were established on mats of submerged aquatic vegetation as opposed to colonies in other studies that were built on emergent vegetation. Wildlife biologists around GSL can manage for nesting Eared Grebes by maintaining a water depth (35–55 cm) that is conducive for submerged aquatic vegetation growth and high invertebrate densities. Climate change models predict that the American Southwest, which is already arid, will become drier in the future. When combined with increasing diversions of water for human uses, the waterbodies where Eared Grebes currently locate their colonies may become entirely dry or too shallow in the future to sustain them.

Abundances and breeding phenology of three sympatric grebes (little grebe Tachybaptus ruficollis, great crested grebe Podiceps cristatus and black-necked grebe Podiceps nigricollis) in Dayet El Ferd, Algeria

In this current study, we examine the abundances and breeding phenology of three sympatric grebes (little, great crested and black-necked grebes) in Dayet El Ferd. These grebes were observed during all the period (2011-2018) in this wetland, except in September when the great crested grebe leaves the region. The abundances of these three grebes show a significant difference. In 2017, the total number of 71 nests was measured. The mean clutch size was 5.23 ± 1.49 eggs per nest. The highest number of eggs per nest was ten eggs, and most nests contained three eggs (N=18).

Interspecific Predatory Waterbird Interactions at a RAMSAR Site

This note describes interactions between four bird species during a predation attempt by Yellow-footed Gull (Larus livens) on an Eared Grebe (Podiceps nigricollis).The interactions among species were documented on video in a mangrove (Rhizophora mangle and Avicennia germinans) area of the Ensenada La Paz (a RAMSAR site) during winter in the southwest Gulf of California, Mexico on 2 February 2019. This is the first report that has documented an effective killing attempt in the Baja California Peninsula and the second in northwestern Mexico of Yellow-footed Gull predation on Eared Grebe. Additionally, kleptoparasitism attempts against the Yellow-footed Gull by a Great Blue Heron (Ardea herodias) and Turkey Vulture (Cathartes aura) are described and suggest that those species may include prey stolen from gulls (family Laridae) more regularly than presently known based on this opportune observation.

Waterbird Migration through a Saline Wetland in the Western Nevada Desert, USA

A great variety of waterbirds migrate across western Nevada, where places to rest or refuel are nearly non-existent. One exception is a little-known industrial pond complex at the Albemarle U.S., Inc. facility in Silver Peak. In this paper we analyzed 3 years (2014-2016) of near-daily counts to document the timing, abundance, and stopover biology of 73 species traversing one of the driest regions in North America. Average annual bird-use-days exceeded 350,000, of which 93% were contributed by species with affinities to highly saline habitats. Individuals of most species (total estimated 110,000-183,000) passed through within a day or so, although some Ruddy Ducks (Oxyura jamaicensis), Eared Grebes (Podiceps nigricollis) and American Avocets (Recurvirostra americana) made prolonged stays. We treat the most abundant species in detail and show that data from sites that can be monitored daily can complement studies from sites where daily censuses are not feasible. The Silver Peak ponds attract sufficient shorebirds to warrant consideration as a Site of Regional Importance in the Western Hemisphere Shorebird Reserve Network.

Exposure of black-necked grebes (Podiceps nigricollis) to metal pollution during the moulting period in the Odiel Marshes, Southwest Spain

European populations of black-necked grebes (Podiceps nigricollis) congregate every year to moult at the salt ponds of the Odiel Marshes (SW Spain). However, the Odiel Marshes are part of one of the most metal-polluted coastal estuaries in the world, which may pose risks to wildlife. We assessed the exposure of grebes to metal pollution during the critical moulting period in the Odiel Marshes and its potential to cause adverse health effects. Levels of metals in red blood pellet (as a biomarker of exposure), plasma carotenoids, eye redness, and body condition (as biomarkers of effects) were studied. Metal content was also analyzed in the brine shrimp Artemia parthenogenetica, the most important food for grebes in this hypersaline ecosystem during the moulting period. Results showed that, in comparison to toxicity thresholds, grebes had relatively high blood levels of arsenic (As), mercury (Hg) and zinc (Zn). The high loads found in Artemia and the way blood levels vary during the moulting period indicate that shrimp consumption may be the main route of metal exposure for grebes. Plasma carotenoids and body condition showed a positive association with exposure to As, while the relationship of lutein-like carotenoids with Hg accumulation was negative at the beginning of the moulting period to become positive afterwards. Moreover, eye redness was negatively affected by As accumulation. Factors including food resource availability, seasonal fluctuations in physiological status, and interannual variations in the degree of environmental contamination should be considered in monitoring efforts when using moult migrant waterbirds as sentinel species.