Foraging niche partitioning in sympatric seabird populations

Abstract

Sympatric species must sufficiently differentiate aspects of their ecological niche to alleviate complete interspecific competition and stably coexist within the same area. Seabirds provide a unique opportunity to understand patterns of niche segregation among coexisting species because they form large multi-species colonies of breeding aggregations with seemingly overlapping diets and foraging areas. Recent biologging tools have revealed that colonial seabirds can differentiate components of their foraging strategies. Specifically, small, diving birds with high wing-loading may have small foraging radii compared with larger or non-diving birds. In the Gulf of St-Lawrence in Canada, we investigated whether and how niche differentiation occurs in four incubating seabird species breeding sympatrically using GPS-tracking and direct field observations of prey items carried by adults to chicks: the Atlantic puffin (Fratercula arctica), razorbill (Alca torda), common murre (Uria aalge), and black-legged kittiwake (Rissa tridactyla). Although there was overlap at foraging hotspots, all species differentiated in either diet (prey species, size and number) or foraging range. Whereas puffins and razorbills consumed multiple smaller prey items that were readily available closer to the colony, murres selected larger more diverse prey that were accessible due to their deeper diving capability. Kittiwakes compensated for their surface foraging by having a large foraging range, including foraging largely at a specific distant hotspot. These foraging habitat specialisations may alleviate high interspecific competition allowing for their coexistence, providing insight on multispecies colonial living.

Foraging trips and isotopic niche of chick-rearing South Georgian diving petrels from the Kerguelen Islands

“…For each bird, we calculated the time spent foraging in each visited 0.5 x 0.5° cell. To identify foraging/resting state (hereafter foraging, see Fromant et For SGDP, the speed threshold was 9.1 km•h -1 , with a drift speed of 5 km•h -1 (Petalas et al 2021), and average flight speed of 50 km•h -1 . Average flight speed was estimated from the analysis of 15 flying bouts (with regular fixes) using raw data.…”

Predicting Seabird Foraging Habitat for Conservation Planning in Atlantic Canada: Integrating Telemetry and Survey Data Across Thousands of Colonies

“…Within our study area, we documented considerable intraspecific variability in foraging ranges and distance from coastlines. Foraging effort and ranges may also be influenced by interspecific competition within colonies (Delord et al, 2020;Petalas et al, 2021) as well as density-dependent intraspecific competition and interference driven by colony size (Lewis et al, 2001;Grecian et al, 2012;Gaston et al, 2013;Jovani et al, 2016) and local prey abundance and/or prey condition (Burke and Montevecchi, 2009;Elliott et al, 2009). We were unable to formally test this with our data given the small number of tracked colonies for each species (in contrast to Wakefield et al, 2017).…”

Modularity in temporal co-occurrence networks at a stopover site reveals strong co-migration fidelity in African-European migratory landbirds over time

“…Several studies have shown that trophically similar species switch to using different foraging substrates, as well as different attack manoeuvres to avoid competition and allowing coexistence (Kent & Sherry, 2020; Pigot et al, 2020). This is the case of species living in highly competitive environments as, for instance, large colonies of seabirds, where slight differences in foraging niches represent an evolutionary adaptation to reduce niche overlap (Petalas et al, 2021). Our findings show no association between co-migration fidelity and foraging strategies, neither in females, nor in males, possibly suggesting the onset of sex-independent foraging mechanisms promoting coexistence at stopover area.…”

“…Almost all species investigated in our study have a strictly carnivorous diet and feed mainly on insects, with the exception of the European turtle dove, Streptopelia turtur and the Eurasian golden oriole Oriolus oriolus , which are classified mainly as granivores’ ground feeding species, but have nevertheless variable foraging niches [53]. Several studies have shown that species with similar diets switch to alternative foraging substrates and different predatory behaviour to avoid competition [53,71]. Our findings show no association between co-migration fidelity and foraging strategies, suggesting the existence of species-independent foraging mechanisms promoting coexistence at stopover areas.…”