Among-year and within-population variation in foraging distribution of European shags Phalacrocorax aristotelis over two decades: Implications for marine spatial planning

Bogdanova, Maria I.; Wanless, Sarah; Harris, Michael; Lindström, Jan; Butler, Adam; Newell, Mark A.; Sato, Katsufumi; Watanuki, Yutaka; Parsons, Matt; Daunt, Francis

doi:10.1016/j.biocon.2013.12.025

Cited by 52 publications

(68 citation statements)

References 33 publications

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“…Two types of accelerometer and one type of GPS logger were used: M190L-D2GT (15 mm diameter, 53 mm length, 16 g in the (Table 1), supporting previous findings in this population (Bogdanova et al, 2014), we considered that our wind data were representative of the wind conditions experienced by all study individuals whilst on foraging trips. To make the wind data comparable across years, the data set from 2010 was sub-sampled at 5 min intervals.…”

Section: Materials and Methods Fieldwork And Instrumentssupporting

confidence: 56%

European shags optimize their flight behavior according to wind conditions

Kogure

Sato

Watanuki

et al. 2016

Journal of Experimental Biology

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Aerodynamics results in two characteristic speeds of flying birds: the minimum power speed and the maximum range speed. The minimum power speed requires the lowest rate of energy expenditure per unit time to stay airborne and the maximum range speed maximizes air distance traveled per unit of energy consumed. Therefore, if birds aim to minimize the cost of transport under a range of wind conditions, they are predicted to fly at the maximum range speed. Furthermore, take-off is predicted to be strongly affected by wind speed and direction. To investigate the effect of wind conditions on take-off and cruising flight behavior, we equipped 14 European shags Phalacrocorax aristotelis with a back-mounted GPS logger to measure position and hence ground speed, and a neck-mounted accelerometer to record wing beat frequency and strength. Local wind conditions were recorded during the deployment period. Shags always took off into the wind regardless of their intended destination and take-off duration was correlated negatively with wind speed. We combined ground speed and direction during the cruising phase with wind speed and direction to estimate air speed and direction. Whilst ground speed was highly variable, air speed was comparatively stable, although it increased significantly during strong head winds, because of stronger wing beats. The increased air speeds in head winds suggest that birds fly at the maximum range speed, not at the minimum power speed. Our study demonstrates that European shags actively adjust their flight behavior to utilize wind power to minimize the costs of take-off and cruising flight.

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Section: Materials and Methods Fieldwork And Instrumentssupporting

confidence: 56%

European shags optimize their flight behavior according to wind conditions

Kogure

Sato

Watanuki

et al. 2016

Journal of Experimental Biology

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“…Theory suggests that diet diversifies when predominant prey become scarce and/or lessen in profitability (Stephens & Krebs 1986), and empirical evidence in other seabird studies supports this (Croxall et al 1999, Cosolo et al 2011. Shags exploit a wide range of prey (Barrett 1991, Velando & Freire 1999, Lilliendahl & Solmundsson 2006, Cosolo et al 2011, Michelot et al 2017) and can adjust their foraging behaviour in response to a change in availability of different prey types within their foraging range (Wanless et al 1998, Daunt et al 2007, Bogdanova et al 2014, Michelot et al 2017. Changes in the availability of sandeels, non-sandeels or both may have contributed to the diet shift in our study population since many fish species have experienced changes in abundance and distribution in the N orth Sea linked to ocean warming (Perry et al 2005, Hiddink & ter Hofstede 2008, Heath et al 2012.…”

Section: Diet Trendsmentioning

confidence: 96%

“…Following Frederiksen et al (2004), we calculated the mean of February and March SST for an inshore area surrounding the Isle of May (bounded by ca. 56°0' to 56°4' N, and 2°7' to 2°3' W), overlapping with the summer foraging range of this population (Bogdanova et al 2014).…”

Section: Annual Sandeel Proxiesmentioning

confidence: 99%

“…Shags and other inshore species may be particularly susceptible to this effect because of their highly restricted foraging range in the breeding season (mean ± SD max. range bird −1 in the Isle of May breeding population: 17.7 ± 8.4 km; Bogdanova et al 2014). However, breeding population size, which declined markedly over the study period, was removed from all models in the detrending analysis, suggesting that other factors were more important in explaining the dietary trends.…”

Section: Population Densitymentioning

confidence: 99%

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From days to decades: short- and long-term variation in environmental conditions affect offspring diet composition of a marine top predator

Howells¹,

Burthe²,

Green³

et al. 2017

Mar. Ecol. Prog. Ser.

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Long-term changes in climate are affecting the abundance, distribution and phenology of species across all trophic levels. Short-term climate variability is also having a profound impact on species and trophic interactions. Crucially, species will experience long-and short-term variation simultaneously, and both are predicted to change, yet studies tend to focus on only one of these temporal scales. Apex predators are sensitive to long-term climate-driven changes in prey populations and short-term effects of weather on prey availability, both of which could result in changes of diet. We investigated temporal trends and effects of long-and short-term environmental variability on chick diet composition in a North Sea population of European shags Phalacrocorax aristotelis between 1985 and 2014. The proportion of their principal prey, lesser sandeel Ammodytes marinus, declined from 0.99 (1985) to 0.51 (2014), and estimated sandeel size declined from 104.5 to 92.0 mm. Concurrently, diet diversification increased from 1.32 (1985) to 11.05 (2014) prey types yr −1 , including members of the families Pholidae, Callionymidae and Gadidae. The relative proportion of adult to juvenile sandeel was greater following low sea surface temperatures (SSTs) in the previous year. In contrast, the proportion of Pholidae and prey richness were higher following high SST in the previous year. Within a season, the proportion of sandeel in the diet was lower on days with higher wind speeds. Crucially, our results showed that diet diversification was linked to trends in SST. Thus, predicted changes in climate means and variability may have important implications for diet composition of European shags in the future, with potential consequences for population dynamics.

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“…Because the data set includes several turtles that were re-tracked in successive nesting seasons, following [85], we quantified the inter-annual variation in core residence areas as (2a overlap /(a1 + a2), where a1 and a2 are the areas of the two respective 50% kernel contours and a overlap is the area of overlap.…”

Section: Delineation Of In-water Residence Areasmentioning

confidence: 99%

Bahamas connection: residence areas selected by breeding female loggerheads tagged in Dry Tortugas National Park, USA

Hart

Sartain

Fujisaki

2015

Animal Biotelemetry

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Background: Delineation of home ranges, residence and foraging areas, and migration corridors is important for understanding the habitat needs for a given species. Recently, many population segments of Northwest Atlantic loggerhead sea turtles (Caretta caretta) were designated as endangered or threatened; the smallest subpopulation is in the Dry Tortugas. Foraging and residence areas for this subpopulation have not been defined outside the Gulf of Mexico. Here, for Dry Tortugas loggerheads that traveled to the Bahamas, we use a combination of switching state-space modeling (SSM) and home-range estimators to determine migration period, spatially delineate and describe residence areas, and examine inter-annual home-range repeatability.

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Among-year and within-population variation in foraging distribution of European shags Phalacrocorax aristotelis over two decades: Implications for marine spatial planning

Cited by 52 publications

References 33 publications

European shags optimize their flight behavior according to wind conditions

European shags optimize their flight behavior according to wind conditions

From days to decades: short- and long-term variation in environmental conditions affect offspring diet composition of a marine top predator

Bahamas connection: residence areas selected by breeding female loggerheads tagged in Dry Tortugas National Park, USA

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