Geology topics

Valentina Colodro

Publications and source records attributed to Valentina Colodro.

8 recordsLinked to original sources

USGS2024

Breeding population size of the Pink-footed Shearwater Ardenna creatopus on Isla Mocha, Chile

Species population estimates are a fundamental component of conservation planning, but there are deficiencies in reliable data for many seabirds. The Pink-footed Shearwater Ardenna creatopus is a seabird that breeds on three islands worldwide, with the largest population on Isla Mocha, Chile. We aimed to update the breeding population estimate of Pink-footed Shearwaters on Isla Mocha, comparing results from design- and model-based estimation methods. We counted shearwater burrows in 220 randomly generated five-meter-radius plots across pre-defined strata on Isla Mocha. We estimated total number of burrows using area-based extrapolation (design-based method), and separately using a model predicting burrow density based on habitat (model-based method). We multiplied burrow abundance estimates by burrow occupancy for final population estimates. The stratum-area-weighted burrow density estimate for the 15.8 km 2 study area was 0.0106 burrows·m -2 (standard error [SE] = 0.0030). The average island-wide proportion of occupied burrows was 0.758 (standard deviation [SD] = 0.121). The design-based method estimated 168 209 burrows (95% confidence interval [CI] = 74 715-261 704, coefficient of variation [CV] = 0.28), and 127 503 breeding pairs (95% CI = 87 610-167 395). The model-based method estimated 233 436 burrows (95% CI = 151 237-332 179, CV = 0.19) and 181 859 breeding pairs (95% CI = 95 773-267 945, CV = 0.24). These population estimates are greater than previous estimates for Isla Mocha, whose means ranged from 19 440-42 095 breeding pairs. Because our study design differed from those used to generate previous estimates, our estimate should be considered a stand-alone result rather than an increase in the breeding population. Because of the low fit of the model-based result, the design-based result may be a more reliable estimate to use for species management efforts. Based on our estimate, approximately 90% of the Pink-footed Shearwater world population breeds on Isla Mocha, and with its restriction to only three breeding localities world-wide, the species remains vulnerable. The full manuscript in Spanish can be found in Appendix 1, available on the website.

Isla Mocha↗

USGS2023

Global assessment of marine plastic exposure for oceanic birds

Plastic pollution is distributed patchily around the world’s oceans. Likewise, marine organisms that are vulnerable to plastic ingestion or entanglement have uneven distributions. Understanding where wildlife encounters plastic is crucial for targeting research and mitigation. Oceanic seabirds, particularly petrels, frequently ingest plastic, are highly threatened, and cover vast distances during foraging and migration. However, the spatial overlap between petrels and plastics is poorly understood. Here we combine marine plastic density estimates with individual movement data for 7137 birds of 77 petrel species to estimate relative exposure risk. We identify high exposure risk areas in the Mediterranean and Black seas, and the northeast Pacific, northwest Pacific, South Atlantic and southwest Indian oceans. Plastic exposure risk varies greatly among species and populations, and between breeding and non-breeding seasons. Exposure risk is disproportionately high for Threatened species. Outside the Mediterranean and Black seas, exposure risk is highest in the high seas and Exclusive Economic Zones (EEZs) of the USA, Japan, and the UK. Birds generally had higher plastic exposure risk outside the EEZ of the country where they breed. We identify conservation and research priorities, and highlight that international collaboration is key to addressing the impacts of marine plastic on wide-ranging species.

Nature Communications↗

USGS2022

Pink-footed Shearwater Ardenna creatopus

The Pink-footed Shearwater’s life history is tied to the Humboldt and California upwelling currents in the Eastern Pacific Ocean. It is larger than other shearwaters in its range, other than Flesh-footed Shearwater Ardenna carneipes. It is also distinct in appearance with pinkish bill and feet, pale underparts, and brown to grayish upperparts. It is known to breed on the Juan Fernández Islands and Isla Mocha, off central Chile. Birds spend the non-breeding period in waters off Peru and northward to waters off the west coast of North America. Breeding occurs in colonies, where pairs nest in burrows and the female lays a single egg. Breeding colonies generally are located on steep slopes in both open and forested habitats. During the breeding period, the species forages mainly in waters over the relatively narrow continental shelf as well as over deep offshore waters, depending on breeding colony. During the non-breeding period, individuals concentrate near the continental shelf-break and slope, and in more pelagic waters while making migratory movements. The Pink-footed Shearwater preys on fish and squid by seizing them at the surface or by making shallow dives. Foraging is often in association with albacore, dolphins, other seabirds, and fishing vessels. Pink-footed Shearwater is listed as Vulnerable by the IUCN and Endangered by Chile and Canada. Principal conservation threats are mortality from fisheries bycatch (especially in South American fisheries), and predation and habitat degradation from introduced mammals on breeding islands.

Birds of the World↗

USGS2021

Global political responsibility for the conservation of albatrosses and large petrels

Migratory marine species cross political borders and enter the high seas, where the lack of an effective global management framework for biodiversity leaves them vulnerable to threats. Here, we combine 10,108 tracks from 5775 individual birds at 87 sites with data on breeding population sizes to estimate the relative year-round importance of national jurisdictions and high seas areas for 39 species of albatrosses and large petrels. Populations from every country made extensive use of the high seas, indicating the stake each country has in the management of biodiversity in international waters. We quantified the links among national populations of these threatened seabirds and the regional fisheries management organizations (RFMOs) which regulate fishing in the high seas. This work makes explicit the relative responsibilities that each country and RFMO has for the management of shared biodiversity, providing invaluable information for the conservation and management of migratory species in the marine realm.

Science Advances↗

USGS2019

Overlap of Pink-footed Shearwaters and central Chilean purse-seine fisheries: Implications for bycatch risk

Understanding susceptibility of seabirds to fisheries bycatch requires quantifying overlap of seabird at-sea habitat with fisheries’ distribution and effort. Pink-footed Shearwaters (Ardenna creatopus) are vulnerable seabirds that breed only in Chile. Recently, high rates of Pink-footed Shearwater bycatch (i.e. >1,500 observed mortalities 2015–2017) were documented by observers in central Chilean purse-seine fisheries. We present analysis of Pink-footed Shearwater at-sea movements and overlap with central Chilean purse-seine fleets targeting common sardine (Strangomera bentincki), Peruvian anchoveta (Engraulis ringens), and Chilean jack mackerel (Trachurus murphyi). To determine overlap during 2015–2017, we paired locations from 49 Pink-footed Shearwaters rearing nestlings at Isla Mocha, Chile, with locations and number of observed purse-seine sets in central Chile. Pink-footed Shearwaters typically visited waters ≤30 km offshore throughout central Chile. Foraging trip durations varied interannually, with longer trips in 2016, but all years revealed persistent foraging hotspots near Valdivia, the Gulf of Arauco, and Isla Mocha, Chile. Greatest overlap between Pink-footed Shearwaters and fisheries occurred with the sardine/anchoveta fleet near Valdivia (artisanal and industrial) and the Gulf of Arauco (artisanal); overlap with the jack mackerel fleet was minimal. Given Pink-footed Shearwater bycatch documented in these fisheries, this overlap may indicate risk of bycatch for these birds, although we did not directly quantify shearwater–fisheries interaction. Our results can inform further fishery monitoring efforts, as well as collaboration among scientists, managers, and fishers to identify, quantify, and reduce fisheries bycatch of Pink-footed Shearwaters within Chile and internationally.

The Condor↗

USGS2019

Eastern Pacific migration strategies of pink-footed shearwaters Ardenna creatopus: Implications for fisheries interactions and international conservation

The pink-footed shearwater Ardenna creatopus has a breeding range restricted to 3 central-Chilean islands and travels north in the eastern Pacific Ocean during the non-breeding period. Despite its Vulnerable IUCN status, the locations and relative importance of core non-breeding areas and migratory pathways of the species are not well understood. During 5 years between 2006 and 2015, we tracked the movements of 42 after-hatch-year pink-footed shearwaters in the non-breeding season using satellite tags. Tracked shearwaters exhibited 2 post-breeding-season migration strategies: 28% of individuals traveled 1600-2500 km north from their colonies to spend the entire non-breeding season off Peru, and 72% traveled 8000-11000 km north to waters off western North America (Baja California, Mexico, to southernmost Canada). Individuals that traveled to North America stopped in Peruvian waters on each leg of the migration, making this a migratory bottleneck. Core non-breeding-season areas included continental shelf and slope waters off Trujillo to Lima (Peru), central Baja California (Mexico), southern to central California (USA), and central Oregon (USA) to southern Vancouver Island (Canada). Of 12 national exclusive economic zones (EEZs) encountered north of their breeding range, birds primarily utilized the USA, Peru and Mexico, and to a lesser degree Chile, Canada, and Ecuador. Bycatch in fisheries was recently identified as a significant at-sea threat to pink-footed shearwaters, and we found evidence of pink-footed shearwater bycatch in 6 EEZs encountered by tracked birds, although quantification of bycatch magnitude is variable and not all fisheries have been studied.

Endangered Species Research↗

USGS2016

Migratory routes and at-sea threats to Pink-footed Shearwaters

The Pink-footed Shearwater (Ardenna creatopus) is a seabird with a breeding range restricted to three islands in Chile and an estimated world population of approximately 56,000 breeding individuals (Muñoz 2011, Oikonos unpublished data). Due to multiple threats on breeding colonies and at-sea, Pink-footed Shearwaters are listed as Endangered by the government of Chile (Reglamento de Clasificación de Especies, 2011), Threatened by the government of Canada (Environment Canada 2008), and are listed under Appendix 1 of the Agreement on the Conservation of Albatrosses and Petrels (ACAP 2013). A principal conservation concern for the species is mortality from fisheries bycatch during the breeding and non-breeding seasons; thus, identification of areas of overlap between at-sea use by Pink-footed Shearwaters and fisheries is a high priority conservation objective (Hinojosa Sáez and Hodum 1997, Mangel et al. 2013, ACAP 2013). During the non-breeding period, Pink-footed Shearwaters range as far north as Canada, although little was known until recently about migration routes and important wintering areas where fisheries bycatch could be a risk. Additionally, Pink-footed Shearwaters face at-sea threats during the non-breeding season off the west coast of North America. Recently, areas used by wintering Pink-footed Shearwaters have been identified as areas of interest for developing alternative energy offshore in North America (e.g., floating wind generators; Trident Winds 2016). The goal of our study was to track Pink-footed Shearwater post-breeding movements with satellite tags to identify timing and routes of migration, locate important non-breeding foraging habitats, and determine population distribution among different wintering regions.

Conference Paper↗

USGS2016

First steps for mitigating bycatch of Pink-footed Shearwaters Ardenna creatopus: Identifying overlap of foraging areas and fisheries in Chile

The Pink-footed Shearwater, Ardenna creatopus, is listed as in danger of extinction by Chile and under Annex 1 of ACAP, with an estimated global population of approximately 56,000 individuals. Incidental bycatch of this species in fisheries is thought to be an important cause in population decline (i.e. annual estimated mortality of >1000 adults). This species is an endemic breeder in Chile, nesting only on the Juan Fernandez Archipelago (JFI; 30% of global population), and Isla Mocha (70% of global population). Using miniature GPS and satellite transmitters, we determined foraging areas of Pink-footed Shearwaters during the chick-rearing period in 2002 (JFI) and 2015-2016 (Isla Mocha). We overlaid shearwater tracking data with data from the Instituto de Fomento Pesquero (IFOP) on fishing effort in Chile (type of fishery, number sets per day, location of sets, and target species) to identify fisheries and fishing zones with the greatest potential for Pink-footed Shearwater bycatch. During the 2002-2006 (N = 28 birds total) and 2015 (N = 18 birds) breeding periods, foraging areas were associated with the continental shelf and shelf-break, generally less than 30 km offshore. All foraging trips occurred between 31.5 and 40.0 degrees south, and birds remained in Chile territorial waters 100% of the time. We identified two primary foraging hotspots, one offshore near Talcahuano, Chile (approximately 36-37.5° south), and one offshore north of Valdivia, Chile (approximately 39-39.5° south). Birds tracked from the Juan Fernández Archipelago foraged in the Talcahuano hotspot but did not visit the southerly hotspot near Valdivia. Birds tracked from Isla Mocha used both areas, with a greater proportion of birds using the Valdivia hotspot than the Talcahuano hotspot. Other major areas of use were around the respective breeding colonies from which the birds were tracked. Overlay of these data with fisheries data is currently in progress. Preliminary results indicate extensive overlap of Pink-footed Shearwater foraging grounds with industrial and artisanal purse-seine fisheries within Chile, representing a significant risk of bycatch. Further work could be initiated to track Pink-footed Shearwaters during other life-stages (i.e. pre-breeding and incubation), and would enhance collaborative efforts with fisheries managers and fishers concerned with mitigating bycatch.

Conference Paper↗