Introduction: Sea urchins of the genus Echinometra are ecosystem engineers that burrow into lower intertidal and subtidal rocks, creating shelter for themselves and a variety of marine animals. Objective: To test the hypothesis that motile macroinvertebrates and fishes shelter proportionately more frequently in burrows with Echinometra mathaei, whose spines potentially offer additional protection, than in burrows without E. mathaei. Methods: We studied the motile macroinvertebrates and fishes sheltering in the burrows of the Indo-Pacific Rock-boring Urchin E. mathaei (Type C) at Mana Island, Fiji. Results: Burrows with E. mathaei averaged shorter in length than burrows without E. mathaei. We observed 42 motile macroinvertebrates of at least eight species and 49 fishes of at least eight species in burrows with E. mathaei (n = 1 127), and four motile macroinvertebrates of three species and one fish of one species in burrows lacking E. mathaei (n = 243). Motile macroinvertebrates occurred with statistically equal frequencies in burrows with E. mathaei (3.6 %) and in burrows without E. mathaei (2.5 %). Fishes occurred significantly more frequently in burrows with E. mathaei (4.3 %) than in burrows without E. mathaei (0.4 %). Conclusion: Fishes, but not motile macroinvertebrates, gain more protection from predators by sheltering in burrows with sea urchins, whose spines offer additional protection, than in burrows without sea urchins.

Hybridization is predicted to occur most frequently in closely related species when one species is rare (scarcity of mates hypothesis) and when the rare species of a heterospecific pair is more likely to be female (sexual selection hypothesis). We studied hybridization in mixed breeding colonies of the Western Grebe ( Aechmophorus occidentalis) and Clark's Grebe (A. clarkii) at Clear Lake, California, during 2011-2019. Of 203 mated pairs with at least one Clark's Grebe (the rarer species, attending 15% of nests), 77.3% were conspecific pairs, 20.7% were heterospecific pairs, and 2.0% comprised a Clark's Grebe paired with a presumed hybrid. The proportion of heterospecific pairs was no greater in smaller colonies or later during the breeding season, contradicting the scarcity of mates hypothesis. Of 42 heterospecific pairs, the Clark's Grebe was just as likely to be male (45.2%) as female (54.8%), contradicting the sexual selection hypothesis. Hybridization between these species more likely results from an error in sexual imprinting due to interspecific brood parasitism or from extra-pair copulations.

Many fish species are known to associate with echinoids. We studied the frequency of fishes associating with the diadematid Black Longspine Urchin Diadema setosum and Banded Sea Urchin Echinothrix calamaris in the Phi Phi Islands of southwestern Thailand during July 17–20, 2022. A total of 1373 fish individuals of 20 species associated with 1157 D. setosum, and 11 fish individuals of seven species associated with 76 E. calamaris. The proportion of fish individuals per echinoid host was 8.2 times higher for longer-spined D. setosum (1.19) than for E. calamaris (0.14), and the proportion of echinoids hosting one or more fish was 2.5 times higher for D. setosum (22.9%) than for E. calamaris (9.2%), supporting the hypothesis that fishes prefer to associate with echinoid species with the longest spines, which potentially provide more protection against predators. All fishes associating with echinoids were small (<10 cm); most were adults, but for some species, all were juveniles. All fishes were facultative associates of echinoids. Only three fish species had been previously reported associating with D. setosum and none with E. calamaris; the remaining fish species represent new records of association, including 17 for D. setosum and seven for E. calamaris.

In this note we report the first documented instance of object play in the Royal Tern (Thalasseus maximus).On 28 October 2020, Walker-Roseman was observing and photographing a mixed flock of gulls and terns resting at the water's edge at Ocean Beach Park, just northwest of Lompoc, Santa Barbara County, California (34° 41ʹ 29˝ N, 120° 36ʹ 14˝ W), when one of the Royal Terns suddenly picked up a small stone with its bill and grasped it for several seconds (Figure 1).The stone was brown, smooth, and somewhat flattened, and approximately a third the length of the tern's bill from the gape to the tip.After dropping the stone, the tern stared at it for a few seconds until a passing jogger flushed all the birds away.The tern did not interact with any other birds during the incident.An attempt to find the stone failed because it was quickly buried in the wet sand.Given the frontal view of the tern in the photos we are uncertain whether it was in formative or definitive basic plumage.Several lines of evidence suggest that the tern's manipulation of the stone had no apparent survival function.Geophagy, the consumption of clay or grit, occurs in many taxa of birds but has not been reported among terns (Downs et al. 2019), and the tern did not attempt to swallow the stone.Terns are not known to move stones to find food or use stones as tools to kill prey (Shealer 2002).Royal Terns have not been reported to pick up stones during courtship or nest building, and this observation occurred during the nonbreeding season (Buckley et al. 2021).Object play can be confused with neophilia, which is the exploration, inspection, or manipulation of a novel object (Emery and Clayton 2015), but small stones are ubiquitous on beaches frequented by terns and hardly novel.Thus the tern's manipulation of the stone appears to be a classic case of object play.Because object play is observed more frequently among juveniles than adults, it is often hypothesized to serve as practice for vital adult skills such as foraging, investigating novel objects, and tool use (Hall 1998).However, object play has been reported in adults of the Caspian Tern (King 1981, Cuthbert and Wires 2020) and Sandwich Tern (Hollom 1955, Shealer et al. 2020), plus many other animals (Hall 1998).Previous observations of object play in terns involved algae, dead vegetation, small sticks, molluscs, and fish (

Abstract. Clear Lake is a large (176.7-km2) natural lake in northern California, USA. An estimated 1000 pairs of Western Grebes (Aechmophorus occidentalis) and Clark's Grebes (A. clarkii) nested on the lake prior to massive applications of the pesticide dichlorodiphenyldichloroethane (DDD) to kill the Clear Lake gnat (Chaoborus astictopus) during 1949–1957. Biomagnification of DDD was implicated as the cause of several mass mortality events of grebes and short-term reproductive failure in the 1950s, although other factors such as mercury (Hg) poisoning may have contributed. Successful nesting resumed in 1960 and increased gradually, with up to 165 nests in 1967 but fewer through 1976. Subsequent surveys revealed up to 390 nests annually during 1992–1995 and up to 2675 nests annually during 1996–2010. We conducted 7–29 nest surveys annually during 2010–2019 and found a mean of 3123 nests per year. The annual number of nests varied dramatically (range 898 to 5936) and was unrelated to water level. The grebes nested at 28 sites in Clear Lake and 9 sites in associated wetlands, with proportionately more nests on Clear Lake and fewer nests in adjacent wetlands during years with low water level. Western Grebes attended 84.9% of the nests and Clark's Grebes attended 15.1%. During years with low water, there were proportionately more open water nests, which were anchored to submergent vegetation farther from shore and in deeper water than marsh nests, which were more densely placed in emergent vegetation closer to shore in shallower water. Brood surveys along the perimeter of the lake at the end of each breeding season revealed considerable variation in the number of young (1–599, x̄ = 153.9), young per nest (0.00025–0.118, x̄ = 0.04), and productivity ratio of young to adults (0.0006–0.252, x̄ = 0.07). Reproductive success was unrelated to water level. Wind-generated waves were a major cause of nest failure, destroying up to 35% of a year's nests. Predation on eggs was also a major cause of nest failure. American Crow (Corvus brachyrhynchos) was the dominant predator during the day (84% of predation events), and northern raccoon (Procyon lotor) was the dominant predator at night (98% of predation events). Nocturnal predation by mammals occurred most frequently when water level was high because nests were placed closer to shore and were more accessible. The grebes' breeding population has recovered since DDD biomagnification during the 1950s and may be larger due to 2 introduced fish species competing for plankton with benthic larvae of the Clear Lake gnat, which previously transferred large quantities of biomass from aquatic to terrestrial ecosystems during emergence. However, the grebes' reproductive success remains lower at Clear Lake than at several other breeding localities. The bioaccumulation and biomagnification of toxic chemicals and the periodic reductions of prey fish from hypoxic areas of the lake during periods of intense cyanobacterial and algal blooms may reduce reproductive success. Resumen. Clear Lake es un lago natural grande (176.7 km2) en el norte de California, EEUU. Se estima que 1000 parejas del achichilique occidental (Aechmophorus occidentalis) y achichilique pico naranja (A. clarkii) anidaron en el lago antes de las aplicaciones masivas del pesticida diclorodifenildicloroetano (DDD) para matar al díptero de Clear Lake (Chaoborus astictopus) durante 1949–1957. La biomagnificación de DDD estuvo implicada como la causa de varios eventos de mortalidad masiva de achichiliques y fallas reproductivas a corto plazo en la década de 1950, aunque otros factores pueden haber contribuido, como el envenenamiento por mercurio (Hg). La anidación exitosa se reanudó en 1960 y aumentó gradualmente, con hasta 165 nidos en 1967 pero menos hasta 1976. Los censos posteriores revelaron hasta 390 nidos anualmente durante 1992–1995 y hasta 2675 nidos anualmente durante 1996–2010. Realizamos de 7 a 29 censos de nidos anualmente durante 2010–2019 y encontramos una media de 3123 nidos por año. El número anual de nidos varió drásticamente (rango 898–5936) y no estuvo relacionado con el nivel del agua. Los achichiliques anidaron en 28 sitios en Clear Lake y 9 sitios en humedales asociados, con proporcionalmente más nidos en Clear Lake y menos nidos en humedales adyacentes durante años con bajo nivel de agua. Los achichiliques occidentales asistieron al 84.9% de los nidos y los achichiliques de Clark asistieron al 15.1%. Durante los años con poca agua, hubo proporcionalmente más nidos en aguas abiertas, que estaban anclados a la vegetación sumergida más lejos de la costa en aguas más profundas, que nidos de marismas, que estaban más densamente colocados en la vegetación emergente más cerca de la costa en aguas menos profundas. Los censos de cría a lo largo del perímetro del lago al final de cada temporada de reproducción revelaron una variación considerable en el número de crías (1–599, x̄ = 153.9), crías por nido (0.00025–0.118, x̄ = 0.04), y una tasa de productividad de jóvenes a adultos (0.0006–0.252, x̄ = 0.07). El éxito reproductivo no estuvo relacionado con el nivel del agua. Las olas generadas por el viento fueron una de las principales causas de la falla de los nidos, destruyendo hasta el 35% de los nidos de un año. La depredación de los huevos también fue una de las principales causas del fracaso de los nidos. El cuervo americano (Corvus brachyrhynchos) fue el depredador dominante durante el día (84% de los eventos de depredación) y el mapache del norte (Procyon lotor) fue el depredador dominante durante la noche (98% de los eventos de depredación). La depredación nocturna por mamíferos ocurrió con mayor frecuencia cuando el nivel del agua era alto porque los nidos se colocaron más cerca de la costa y eran más accesibles. La población reproductora de achichiliques se ha recuperado desde la biomagnificación por DDD durante la década de 1950 y puede ser mayor debido a que dos especies de peces introducidas compiten por el plancton con las larvas bentónicas del díptero de Clear Lake, que anteriormente transfirió grandes cantidades de biomasa de los ecosistemas acuáticos a los terrestres durante la emergencia. Sin embargo, el éxito reproductivo de los achichiliques sigue siendo menor que en varias otras localidades de reproducción. La bioacumulación y biomagnificación de sustancias químicas tóxicas y las reducciones periódicas de peces presa de las áreas hipóxicas del lago durante períodos de intensa proliferación de cianobacterias y algas pueden reducir el éxito reproductivo.

Introduction: Echinoids (sea urchins) provide shelter for a variety of facultative or obligatory ectosymbionts. Objective: To evaluate the hypothesis that decapods and fishes prefer to associate with echinoid individuals and species that have longer spines. Methods: We visually studied the frequency of decapod crustaceans and fishes associated with echinoids in shallow water (< 4 m) and deeper water (5-20 m) at Los Cabos, Baja California Sur, Mexico, during 1-6 January 2019. Results: We inspected 1 058 echinoids of six species. Five decapod species associated with three species of echinoids. When compared with other echinoid species, in shallow water, decapods associated 5.1 times more often with the longest-spined echinoid Diadema mexicanum (7.0 times more decapods per individual D. mexicanum); in deeper water, association frequency was similar for all echinoid species. Fourteen fish species associated with four echinoid species. In shallow water, fishes associated 2.6 times more with D. mexicanum (4.5 times more fishes per individual). There was no preferred echinoid species in deeper water. Longer-spined D. mexicanum had more decapods and fishes. Associations were more frequent in shallow water. Multiple individuals and species of decapods and fish often associated together with a single D. mexicanum. The decapod that presumably is Tuleariocaris holthuisi showed a possible obligatory association with one of the equinoids (D. mexicanum); the other decapods and all fish species are facultative associates. Conclusion: Our results support the hypothesis that decapods and fishes associate most frequently with echinoid with the longest spines, presumably to reduce the risk of predation.

The integument of marine mammals provides an ideal substrate for colonization by photosynthetic epizoans. A review of the literature and new data from the harbor seal (Phoca vitulina richardsi) revealed at least eight genera of photosynthetic cyanobacteria and algae colonizing the pelage of six species of pinnipeds. The relationship may be considered a facultative association, beneficial to the photosynthetic epizoans and relatively neutral (but perhaps slightly costly) to their mammalian hosts. We studied the incidence of algal growth on the pelage of harbor seals in central California during 1985-1987 and 2017. The green alga Ulva sp. occurred on adult females throughout the year and rarely occurred on adult males. Algal growth appeared to be most frequent during the breeding season (February to May) and least frequent during the molt and post-molt seasons (June to October). Algal growth occurred more frequently on harbor seals in estuaries than along the coast. Much remains to be learned about the colonization of pinnipeds by photosynthetic epizoans and why some seals are more susceptible to colonization by algae than others.

Summary Cyclonic storms (often called hurricanes, typhoons, or cyclones) often cause population declines in vulnerable bird species, and the intensity of these storms appears to be increasing due to climate change. Prior studies have reported short-term impacts of hurricanes on avifauna, but few have examined long-term impacts. Over two decades (1993–2018), we periodically surveyed a subspecies of West Indian Woodpecker Melanerpes superciliaris nyeanus on San Salvador, a small island in The Bahamas, to determine its distribution on the island, habitat use, and effects of hurricanes on abundance and population size. We conducted passive and playback surveys, supplemented with mist-netting. Woodpeckers were found only in the northern part of San Salvador, despite extensive surveys throughout other accessible areas of the island. Birds occupied areas with taller coppice adjacent to sabal palm Sabal palmetto groves, which were used for nesting. After hurricanes with >160 kph winds passed over San Salvador, woodpecker densities declined to 35–40% of pre-hurricane densities, but generally recovered back to pre-hurricane densities within 2–3 years. Based on an estimated density of woodpeckers within a ~1,400 ha occupied area, we calculated a population size of approximately 240 individuals (CI = 68-408). However, the population declined to far lower numbers immediately following hurricanes. Under IUCN Red List criteria, M. s. nyeanus classifies as ‘Critically Endangered’, and could be especially sensitive to future hurricanes if they occur at a high enough frequency or intensity to prevent the population from rebounding. Given the small size, isolation, and vulnerability of this population, we recommend preservation of the core habitat, continued monitoring, and further research. Our study shows that small, threatened bird populations can be resilient to the effects of hurricanes, but increased intensity of hurricanes, in combination with other threats, may limit this resilience in the future.

Sea anemones rarely prey upon nudibranch molluscs, which employ several effective defensive strategies. We documented a nudibranch, Peltodoris nobilis, partially engulfed by a sea anemone, Anthopleura artemisia, in situ in Northern California on 13 September 2020. It is unknown whether the sea anemone successfully consumed and digested the nudibranch. Previous natural and experimental observations reveal that most nudibranchs either escape from sea anemones or the sea anemones consume and then regurgitate the nudibranchs.

Seven species of flying foxes of the genus Pteropus have been described from the Caroline Islands and Mariana Islands of Micronesia. Among the five extant species, P. ualanus of Kosrae is the least studied. We review the history of research on P. ualanus and summarize data from recent surveys. Early historical accounts suggest that P. ualanus was abundant until a severe population bottleneck, attributed to an infectious disease, allegedly reduced the population to two individuals during 1926–1927. During 1982 and 1983, we found three colonies and a minimum of 600–700 bats in the mountains. Subsequently two new colonies became established in coastal localities by 1994 and 2002 and currently represent the largest colonies. During 2013 and 2014, Hayes visited four confirmed and two possible colonies (three in the mountains, three along the coast) ranging in size from two to 1038 individuals and counted a minimum of 1765 individuals. Long-term changes occurred in the size of colonies. Because not all individuals were counted and at least one other colony likely exists, the population probably exceeds 2000 and may exceed 3000 individuals. The population may not have reached its carrying capacity and may still be increasing. Potential existential threats include infectious disease, typhoons, overhunting, and habitat loss.

Gulls (Laridae) are primarily diurnal, although many species forage opportunistically at night. and several species copulate at night. We used trail cameras to study time-of-day variation in the rate of copulation by Glaucous-winged Gulls Larus glaucescens in a breeding colony (1500+ pairs) at Protection Island. Washington, USA, from 31 May to 07 June 2018. Copulations (n = 353) occurred at a significantly higher rate during the day (0.82/camera-h) than at night (0.51/camera-h), with 76.3% of copulations during the day and 23.7% at night (daylight comprised 66.1% and darkness comprised 33.9% of the study period). The copulation rate peaked shortly before and after dawn, with a second peak before sunset. Copulation rate was lowest during the middle of the day and middle of the night. Glaucous-winged Gulls sleep intermittently during both day and night and have sufficient energy to sustain sporadic copulations during the night, which appears to be a normal part of their reproductive behavior. The most likely advantage of this pattern is an increased opportunity for fertilization with a mate.

The Sanderling (Calidris alba) normally forages on a variety of live prey (Macwhirter et al. 2002).There are only a few previous reports of Sanderlings scavenging dead prey, including the carcasses of dead jellyfish and fishes on beaches (Gochfeld and Burger 1980, King 1981, Grimm 1984, Reneerkens et al. 2009).In two of these reports the Sanderlings scavenged fish carcasses after they had been ripped open by scavenging Herring Gulls (Larus argentatus; Gochfeld and Burger 1980) or Lesser Black-backed Gulls (L.fuscus; King 1981).In this note we document a Sanderling scavenging a crab preyed upon by a foraging Western Gull (L.occidentalis).On the evening of 3 April 2011, Khanzode visited Half Moon Bay, San Mateo County, California, to photograph migrating shorebirds.At 17:51, he observed a Western Gull capture and kill a Northern Kelp Crab (Pugettia producta) on Maverick's Beach at Pillar Point (37° 29′ 47″ N, 122° 29′ 44″ W).As the gull manipulated the crab, a Sanderling flew in, stood within 0.5 m behind or to the side of the gull, and watched the gull devour the crab (see this issue's back cover, top photo).The Sanderling did not attempt to snatch the crab from the gull, and the gull ignored the Sanderling.After spending several minutes consuming a few large morsels of the crab, the gull abandoned the crab's carcass and flew away just after 18:00.Immediately afterward, at 18:01, the Sanderling began picking off the smaller pieces of crab tissue that the gull had left behind in the crab's carapace (back cover, middle and bottom photos).The Sanderling continued feeding on the crab carcass for about 15 min until all of the tissue was consumed.This appears to be the first documented instance of a Sanderling scavenging on prey directly from a predator.Scavenging dead prey from a predator or another scavenger may be passive (beneficial for the perpetrator, neutral for the host) or result from kleptoparasitism, in which dead food is stolen from a host (beneficial for the perpetrator, costly for the host; Brockmann and Barnard 1979, Focardi et al. 2017). Herbert et al. (2019) pointed out that there is a continuum from passively scavenging dropped prey to aggressively coercing a victim to relinquish food.They suggested that the behavior switches from scavenging to kleptoparasitism when a victim takes evasive maneuvers to defend its food.In this case the Western Gull never took evasive measures to avoid losing its food to the Sanderling, which did not attempt to feed on the crab until after the gull departed, so this observation represents an instance of passive scavenging without any benefit or cost to the gull.Although the behavior is rarely reported in the literature, Sanderlings may scavenge prey fragments from predators or other scavengers more frequently than is currently recognized.

The Radial Lionfish, Pterois radiata Cuvier, 1829, is widely distributed across the tropical Indian Ocean and western Pacific Ocean and has been previously documented from most of the major island groups of Micronesia, but not from Kosrae. On 21 June 2014 an adult P. radiata was photographed in shallow water along the eastern edge of Blue Hole near Lelu village, Kosrae, Micronesia, providing the first documented record for Kosrae.

Las aves pueden responder a aumentos recientes en temperatura, cambios en precipitaciones o modificaciones de hábitat a gran escala ya sea adaptándose in situ o desplazando espacialmente su distribución a nuevas áreas. Realizamos una extensiva revisión bibliográfica complementada con datos de eBird sobre aves que posiblemente han expandido su distribución austral en Argentina entre 2009 y 2020. Detectamos un total de 94 especies cuya distribución hacia el sur habría aumentado en la última década en ecorregiones de Yungas, Paranaense, Chaco-Espinal y Andinas. Representan el 9.6% de las especies citadas para el país. Nuestros resultados proporcionan un marco científico dentro del cual los encargados de la toma de decisiones pueden contextualizar la importancia de los cambios medioambientales a escala regional y continental y conocer cómo afecta la distribución de las aves.

The Boa Constrictor ( Boa constrictor ) is a large, heavy-bodied snake inhabiting a diversity of habitats throughout most of South America. It is a dietary generalist, foraging on a wide variety of prey including shrimps, fishes, lizards, birds and mammals. In this note we document a Boa Constrictor preying on a Great Kiskadee ( Pitangus sulphuratus ).

Observations of seabirds stealing food (kleptoparasitism) from marine mammals are rarely reported. During 67 h of observation at Seward, Alaska, where fishers frequently discard scraps of fish, we documented 16 incidents of gulls attempting to kleptoparasitize sea otters (Enhydra lutris) and seven incidents of gulls attempting to kleptoparasitize Steller sea lions (Eumetopias jubatus). An average of 3.5 ± 3.5 SD (range 1–13) glaucous-winged gulls (Larus glaucescens) and < 0.1 ± 0.3 SD (range 0–1) black-legged kittiwakes (Rissa tridactyla) attacked sea otters with discarded fish scraps, with a success rate of 53% per incident and 16% per individual gull. The gulls ignored sea otters with invertebrate prey. An average of 3.6 ± 1.7 SD (range 1–7) glaucous-winged gulls and 0.1 ± 0.4 SD (range 0–1) black-legged kittiwakes attacked sea lions with discarded fish scraps, with a success rate of 29% per incident and 8% per individual gull. Only glaucous-winged gulls succeeded in stealing food, usually comprising fragments of the original item floating on the surface after the victim dived, but twice food was stolen directly from sea otters. To avoid kleptoparasitism, sea otters used five evasive maneuvers (swimming away, diving, rolling, lunging toward gull, and pulling food from gull), whereas sea lions used only two (swimming away and diving). Kleptoparasitism of sea otters and sea lions by gulls is a previously overlooked behavior that merits further study of its potential benefits and costs.

We studied the association of 11 species of fishes with 5 species of echinoids at Roatán, Honduras, from 27 August to 1 September 2017. Fishes associated most frequently with the echinoid Diadema antillarum (34.3% of echinoids, six fish species, n = 146 echinoids), followed by Echinometra viridis (25.0%, three fish species, n = 12), Echinometra lucunter (7.5%, ten fish species, n = 1,834), Eucidaris tribuloides (3.4%, four fish species, n = 116), and Tripneustes ventricosus (7.1%, one fish species, n = 28). Of 196 fishes seeking shelter beside echinoids, Malacoctenus aurolineatus was the most common (41.8% of fishes, three echinoid species), followed by Stegastes adustus (38.8%, three echinoid species), Stegastes diencaeus (6.6%, three echinoid species), Sargocentron coruscum (6.1%, five echinoid species), Chaetodon capistratus (1.5%, one echinoid species), Gobioclinus filamentosus (1.5%, one echinoid species), Pomacanthus paru (1.0%, two echinoid species), Labrisomus nuchipinnis (1.0%, two echinoid species), Equetus punctatus (0.5%, one echinoid species), Microspathodon chryurus (0.5%, one echinoid species), and Thalassoma bifasciatum (0.5%, one echinoid species). None of the fishes associated exclusively with echinoids or was specialized for associating with echinoids, indicating the association was facultative. All fishes were small (< 12 cm). Fishes associated most frequently with the longest-spined echinoid, D. antillarum, supporting the hypothesis that fishes seek shelter among the spines of echinoids to benefit from increased protection from predation.