The dynamic trophic niche of an island bird of prey

Balza, Ulises; Lois, Nicolás A.; Polito, Michael J.; Pütz, Klemens; Salom, Amira; Rey, Andrea Raya

doi:10.1002/ece3.6856

Cited by 13 publications

(17 citation statements)

References 80 publications

(144 reference statements)

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“…Caracaras on Isla de los Estados feed on a restricted diet of mainly marine foragers (Balza et al 2020), and their mercury concentrations were similar to those detected in other raptor species in North America commonly associated with aquatic prey (Bowerman et al 1994;Hughes et al 1997;Cahill et al 1998;Bechard et al 2009). Moreover, in the Southern Hemisphere, only marine top predators, like albatrosses, show similar mercury exposure (Carravieri et al 2017;Cherel et al 2018).…”

Section: Discussionsupporting

confidence: 63%

“…This could be explained by chronic exposure of adults that are at least five years old (Strange 1996). However, several other factors could be responsible for the unexplained variation in our model, including differences in physiology or foraging ecology between age groups (Balza et al 2020).…”

Section: Discussionmentioning

confidence: 99%

“…In particular, the resident population in Franklin Bay (Isla de los Estados) build their nests in close association with Southern Rockhopper penguins (Eudyptes chrysocome, hereafter rockhopper) and are the main predator of their eggs and chicks (Liljesthröm et al 2008;Balza et al 2017). Moreover, caracaras of all ages and breeding status depend on marine resources and particularly on penguin subsidies during breeding season (Balza et al 2020). Rockhoppers breeding on Franklin Bay show feather mercury concentrations amongst the highest ever reported in penguins (5.10 ± 1.46 mg/kg, Brasso et al 2015).…”

Section: Introductionmentioning

confidence: 99%

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The highest mercury concentrations ever reported in a South American bird, the Striated Caracara (Phalcoboenus australis)

et al. 2021

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Mercury is a widely available pollutant associated with negative effects on wildlife, especially top predators. Here, we characterized the mercury concentrations in feathers of Striated Caracara Phalcoboenus australis on Isla de los Estados (Argentina). With feather mercury levels averaging 26.3 mg/kg, this population has the highest mean feather mercury ever reported for a bird population in South America. We propose that the high mercury concentrations are related to the feeding habits of the species: during feather moult, they are strongly associated with a Southern Rockhopper Penguin (Eudyptes chrysocome) colony known to be highly exposed to mercury contamination. Our results suggest that this Striated Caracara population should be monitored for acute effects and potential impacts of mercury toxicity.

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Section: Discussionsupporting

confidence: 63%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The highest mercury concentrations ever reported in a South American bird, the Striated Caracara (Phalcoboenus australis)

et al. 2021

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“…For males we selected: 1) Northern Patagonia baseline: mean δ 15 N values (11.6 ± 0.1 ‰) and mean δ 13 C values (-18.7 ± 0.5‰) of Aulacomya atra (sampled from the northern sector of Patagonia 40˚S to 44˚S; [50]). For females we selected: 2) Southern Patagonia baseline: mean δ 15 N values (12.7 ± 0.5 ‰) and mean δ 13 C values (-15.8 ± 0.5‰) of Aulacomya atra (sampled from the southern sector of Patagonia 48˚S to 52˚S, [50]) and 3) Bahía Franklin baseline: mean δ 15 N values (10.8 ± 0.5 ‰) and mean δ 13 C values (-14.7 ± 0.3‰) of Mytilus chilensis (sampled from Bahía Franklin, Isla de los Estados 54˚47' S, in front of Atlantic cost of Tierra del Fuego, [51]). We assumed all bivalves were completely herbivorous and occupied a TP of 2.…”

Section: Trophic Position Estimatesmentioning

confidence: 99%

Sex-specific spatial use of the winter foraging areas by Magellanic penguins and assessment of potential conflicts with fisheries during winter dispersal

et al. 2021

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Magellanic penguins (Spheniscus magellanicus) disperse widely during winter and are a major consumer of marine resources over the Patagonian Shelf. Magellanic penguins were equipped with geolocators at Martillo Island in late February- early March 2017 and recaptured at the beginning of the next breeding season to recover the devices and to collect blood samples for stable carbon (δ13C) and nitrogen (δ15N) isotope analysis. We evaluated their whole winter dispersal and their trophic niche by sex during the last month of the winter dispersal. Also, we evaluated their spatial overlap with bottom trawl and shrimp fisheries using data from satellite fisheries monitoring. Penguins dispersed northwards up to 42°S and showed latitudinal spatial segregation between sexes during May to August (females were located further north than males). In contrast, during the last month of the winter dispersal females were located more southerly and showed lower trophic position than males. Also, females did not dive as deep as males during winter. We found high overlap between both fisheries and penguin’s spatial use in regions with documented interaction. However, no sex-specific statistical differences with fisheries overlap were found. Our results highlight the importance of understanding the spatial domains of each sex and assessment of their potential conflicts with bottom trawl fishery and shrimp fishery during the winter period.

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“…At least six times, kestrels tried to catch birds (especially small passerines and doves), contrary to their usual diet based on abundant lizards and insects 35 . Widening of trophic niches in island organisms has traditionally been interpreted as linked to disharmony in island ecosystems [36][37][38] . However, this plasticity is tremendously beneficial in ecological catastrophes, where food becomes exceptionally scarce.…”

Section: Discussionmentioning

confidence: 99%

The fate of terrestrial biodiversity during an oceanic island volcanic eruption

Nogales

Guerrero-Campos

Boulesteix

et al. 2022

Sci Rep

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Volcanic activity provides a unique opportunity to study the ecological responses of organisms to catastrophic environmental destruction as an essential driver of biodiversity change on islands. However, despite this great scientific interest, no study of the biodiversity at an erupting volcano has yet been undertaken. On La Palma (Canary archipelago), we quantified the main species affected and their fate during the 85-day eruption (September–December 2021). Our main objective consisted of monitoring the biodiversity subjected to critical stress during this volcanic eruption. We found that all biodiversity within a 2.5 km radius was severely affected after the first two weeks. It is challenging to assess whether volcanism can drive evolutionary traits of insular organisms. Examples are the adaptation of an endemic conifer to high temperatures, selection of functional plant types—secondary woodiness—, effects of the disappearance of invertebrates and their influence in trophic nets and vertebrate trophic plasticity. However, our data suggest that such previous evolutionary changes might continue to favour their resilience during this eruption. Lastly, it is a very good opportunity to assess the extent to which these periodic volcanic catastrophes may constitute temporary windows of repeated opportunities for the evolution and speciation of oceanic island biota.

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The dynamic trophic niche of an island bird of prey

Abstract: Variability in individual diets can have strong effects on community structure (Des Roches et al., 2018) and supports population persistence (Ducatez et al., 2020). Intraspecific variation in diet can be related to several factors, such as sex dimorphism (e.g., Ebenman

Cited by 13 publications

References 80 publications

The highest mercury concentrations ever reported in a South American bird, the Striated Caracara (Phalcoboenus australis)

The highest mercury concentrations ever reported in a South American bird, the Striated Caracara (Phalcoboenus australis)

Sex-specific spatial use of the winter foraging areas by Magellanic penguins and assessment of potential conflicts with fisheries during winter dispersal

The fate of terrestrial biodiversity during an oceanic island volcanic eruption

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