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Page 09: Rediscovering Zion
No full textPage 9 of 12 of the LHI Zion Cemetery Poster Project (FLDOS). Download to view in high resolution.https://digitalcommons.usf.edu/zion_posters/1009/thumbnail.jp
Population Status of the Kermadec Petrel \u3ci\u3e(Pterodroma neglecta juana)\u3c/i\u3e at San Ambrosio Island, Chile
No full textWe visited San Ambrosio Island off northern Chile (26°21′S, 079°47′W) on 10–12 December 2019. We found a large population of Kermadec Petrel Pterodroma neglecta juana that appeared to be healthy. In the area that we could survey, we estimated at least 22686 breeding pairs, which is an underestimate of the entire population as we could not access some steep areas. Introduced mammals, which have since been eradicated, caused a loss of island vegetation that might be a drawback for this population, as shading from the sun appears to be important for nest-site selection. Egg-laying started by early December. We assessed 223 birds with respect to coloration: most birds were intermediate phase (65%) and the rest were either very dark (23%) or very pale (12%). We found skeletal remains of goats and rabbits on the island but no living mammals, although a single goat may still be alive. In the context of an estimated world population of ~100 000 pairs of Kermadec Petrel, the San Ambrosio Island population contributes significantly
Avifauna Associated with an Otter-trawl Fishery in a Tropical Estuary
No full textOtter trawls are commonly used in fisheries for benthic fishes, and they provide a source of food to many marine birds. This study aimed to quantify the response of birds, by species, attracted to forage at fishing vessels in Ribeira Bay, Angra dos Reis, Rio de Janeiro, Brazil. Sampling was conducted every two months in 2006 at five stations, for a total of 30 trawls; fish were collected for 20 minutes per trawl. Bird counts were recorded just before the trawling started, when it began, 10 minutes after trawling began, and 10 minutes after it stopped. After trawling, 10 fresh dead fish were released into the water, and we recorded the number of successful and unsuccessful attacks. Our 224 observations included eight bird species; three species—Magnificent Frigatebird Fregata magnificens, Neotropic Cormorant Phalacrocorax brasilianus, and Great Egret Ardea alba—accounted for 68.3%, 10.7%, and 5.8% of the records, respectively. Scoring highest in a Frequency of Occurrence Index were the Magnificant Frigatebird, South American Tern Sterna hirundinacea, and Brown Booby Sula leucogaster, with 75%, 30%, and 25%, respectively. When trawling started, 21% of the eventually recorded birds approached the boat, but after 10 minutes, they dispersed. After trawling stopped, 77% of the eventually recorded birds approached. Most attacks on discarded fish were performed by frigatebirds (79%), which were also the most efficient in getting fish (83%). Our results emphasize the important association of frigatebirds with trawling, in accord with its kleptoparasitic mode of foraging
Non-breeding Movements and Foraging Ecology of the Black Guillemot \u3ci\u3eCepphus grylle\u3c/i\u3e in Atlantic Canada
No full textUnderstanding the movements of seabirds, which are important ecological indicators, can provide new insights into physical and biological aspects of the marine environment. This information can also be used in planning marine conservation and oil spill response strategies. Though Black Guillemots Cepphus grylle are widely distributed in the coastal waters of eastern and arctic Canada, little is known about their movements during the non-breeding season. We used a combination of global location sensors and stable-isotope analyses on Black Guillemots breeding on Country Island, Nova Scotia, Canada and on Kent Island, New Brunswick, Canada to examine their non-breeding movements and trophic ecology in 2017–2018. Overall, the two populations dispersed an average of 157 km from their breeding colonies (max. 494 km) throughout the region, reaching areas that included the Scotian Shelf, Gulf of St. Lawrence, Bay of Fundy, and Gulf of Maine; both populations overlapped in the Bay of Fundy during the winter. Trophic levels (δ15N) and foraging locations (δ13C) differed between the colonies. Birds from Country Island foraged at higher trophic levels and in less benthic waters than Kent Island birds overall, and birds from both colonies foraged at higher trophic levels in autumn than in winter. This indicates that foraging strategies differ between Black Guillemot populations and that diet varies between seasons, even when foraging habitats do not. Our findings, combined with other seabird, fish, and marine mammal tracking studies, can inform marine management decisions in Atlantic Canada
Fishy Tales: Behaviour of Schooling Fish Escaping from Terns
No full textThe aim of this study is to develop a better understanding of seabird foraging behaviour and the anti-predator behaviour of their prey. Studies of seabirds’ foraging and prey-capture behaviour, as it relates to the evasive and escape behaviour of schooling fish, are sparse. Our study was carried out at One Tree Reef on the southern end of the Great Barrier Reef, Australia. A school of hardyheads Pranesus capricornensis sheltered in the shallows over the sand flats in front of the research station for 14 non-consecutive days. In that time, Lesser Crested Terns Thalasseus bengalensis were observed for 10 hours from above the surface in 37 foraging bouts and for 40 minutes from underwater in at least one foraging bout. In each foraging bout, a single tern dived into the school. We found that terns on average dived at a rate of 0.67 ± 0.35 dives/minute from 4–5 m above the surface. The depth range of dives was 43–58 cm. Therefore, fish within 58 cm of the surface were potentially accessible. The total length of the hardyheads was 10–12 cm, which is within the size range useable by terns. Fish used flash expansion to escape diving terns and formed a vacuole around birds as they slowly ascended to the surface. This escape manoeuvre was effective about 80% of the time. The fish that were caught did not respond to the escape movements of the fish above them and, therefore, were isolated. Fish also used the C-startle response to escape terns underwater and in mid-air. The anti-predator manoeuvres of hardyheads are similar to those observed among Clupea spp. (herrings and sardines) and Ammodytes spp. (sand eels) escaping sub-surface predators. Hardyheads and sardines react in the same way to gannets Morus spp. and terns that plunge dive directly to their prey, partially confirming the prediction that results for plunge-diving gannets are generalisable to other gannets and boobies (Sula spp.), terns and gulls (Larus spp.), tropicbirds (Phaethon spp.), pelicans (Pelecanus spp.), and kingfishers (Alcedinidae)
Albatross Population Monitoring Using Satellite Imagery, a Case Study: Short-tailed Albatross \u3ci\u3ePhoebastria albatrus\u3c/i\u3e at the Senkaku Islands
No full textAccurate monitoring of vulnerable albatross populations is essential to their conservation. Herein, we explore the prospect of monitoring one particular remote albatross population with a view to promoting accurate worldwide monitoring of vulnerable albatross populations. We used very high-resolution (VHR) satellite images to count nesting Short-tailed Albatrosses Phoebastria albatrus on two islands of the Senkaku group, western North Pacific Ocean, where conventional monitoring has not occurred for 19 years due to a geopolitical territory dispute. Despite count uncertainties across rocky terrain, many birds were clearly discernible using the highest resolution image available of Minami-kojima. The result was a count of 132 (109–162) nesting pairs in the 2020/21 breeding season (the timing of the count indicates the presence of nesting birds); this compares to a count of 52 when the population was last surveyed in 2002. On Kita-kojima, no birds were counted in images available for the 2019/20 and 2020/21 breeding seasons; one bird (a chick) was counted in 2002. If accurate, these counts are inconsistent with existing projections of increasing abundance of this species at the Senkakus (190 breeding pairs by 2018/19). Based on our findings, we suggest that reliable satellite image-based counts, independent of ground verification, is an achievable goal for albatrosses. Images must be of the highest possible resolution, with angle and timing optimized appropriately for the breeding site. There is a need for standardization of specific procedures and methodologies, a task that is well-suited to The Working Group of the Agreement on the Conservation of Albatrosses and Petrels
Spatial Effects in Relation to Reproductive Performance of Common Murres \u3ci\u3eUria aalge\u3c/i\u3e at a Re-established Colony
No full textA main goal of seabird colony restoration is for the colony to become self-sustaining. To do so, elevated rates must be attained in (1) reproductive success and (2) recruitment by immigrants and birds produced at the colony. Thus, an understanding of the factors affecting reproductive success and recruitment at restoration sites is vital. We examined how spatial features at the colony level affected reproductive success of Common Murres Uria aalge (hereafter, murres) over a six-year period at Devil’s Slide Rock, California, a colony re-established using social attraction techniques. Clusters of sites with similar egg-laying dates, as well as high hatching and breeding success, occurred in the densest portion of the colony, which was also the last area occupied by murres at the time of extirpation and the first area to be re-colonized. Clusters of sites with low success occurred in outlying, low-density portions of the colony. Breeding success, influenced largely by high fledging success, averaged \u3e 60% most years. Reproductive success was greatest at breeding sites with earlier egg-laying dates, those in closest proximity to the breeding sites of other murres and the Brandt’s Cormorant Urile penicillatus, and those outside Brown Pelican Pelecanus occidentalis disturbance zones. Based on our findings, for future murre restoration projects in the California Current System, we suggest (1) placing social attraction equipment in the area(s) last utilized by murres prior to extirpation, (2) attempting to establish two dense breeding groups, (3) targeting sites already utilized regularly by nesting Brandt’s Cormorants, and (4) avoiding sites or habitats prone to disturbance by larger and aggressive species such as Brown Pelicans, Bald Eagles Haliaeetus leucocephalus, or Common Ravens Corvus corax
Albatross and Petrel Interactions with an Artisanal Squid Fishery in Southern Peru during El Niño, 2015-2017
No full textWe report on the occurrence of albatrosses (Diomedeidae) and petrels (Procellariidae) associated with an artisanal small-scale fishery (SSF) for Humboldt Squid Dosidicus gigas in waters of southern Peru during El Niño 2015–2016 and coastal El Niño 2017. We deployed as observers on a number of fishing trips to assess seabird interactions. White-chinned Petrels Procellaria aequinoctialis and Waved Albatross Phoebastria irroata were the most abundant species observed, followed by Salvin’s Thalassarche salvini and Chatham T. eremita albatross, and Cape Petrels Daption capense. The majority of procellariid species (\u3e 60% of total birds) visited while vessels were positioned over the continental slope. Salvin’s and Chatham albatross, and White-chinned Petrels, were mostly absent during summer (only 5% and 15% of birds present, respectively), but Waved Albatross and Cape Petrels were present year-round. Thus, the prevalence of each of these species was disproportionate relative to expectation based on non-fishery surveys. All assessed species foraged on offal discards associated with the fishery (~17%), with a higher frequency of consumption among Salvin’s (27%) and Chatham (21%) albatross; in contrast, Waved Albatross largely fed on pelagic fish at the surface. Bycatch rate was found to be low; one Chatham Albatross was hooked and released in a hand-held squid jig (0.042 By Catch Per Unit Effort [BPUE] per fishing trip, n = 16). Probably due to El Niño conditions, Waved Albatross were more abundant than expected (43.9% of albatross, and 2.8% of total seabirds observed) and were 1 300–1 400 km farther south than their usual southern limits. We report the first sighting of Southern Royal Albatross Diomedea epomophora in Peru. Bycatch in longline fisheries are a conservation concern, but the magnitude and constant growth of SSFs, especially for Humboldt Squid, needs to be further investigated