Foraging movements of Magellanic Penguins Spheniscus magellanicus in the Beagle Channel, Argentina, related to tide and tidal currents

Abstract

This study investigates the movements of Magellanic Penguins Spheniscus magellanicus breeding on Isla Martillo during the early chick-rearing period. Foraging paths were reconstructed using GPS loggers that registered the penguins 0 geographic position, water temperature and depth at regular intervals. The relationship between penguins 0 movements and search strategies, tide and tidal currents were assessed. Mean trip duration was on average 14.7 ± 6.9 h (33% overnight), and the maximum distance reached was 24 ± 10 km. All penguins studied foraged to the east of the colony. We identified three phases based on the sinuosity and speed of the trajectory: transit, central and return. Foraging effort was higher during the central phase, followed by the transit phase, and lower in the return phase. Foraging success, measured as the percentage of time at the bottom during each phase, was also highest during the central phase. In all birds studied, the central phase of the foraging trip took place during ebb tide, and birds travelled to the foraging areas with flow tide running in the same direction of displacement. Our study suggests that penguins take advantage of tidal currents to facilitate their movements to and from the main foraging area, thereby reducing the energy expended. Moreover, we suggest that piscivorous diving birds may enhance their catch rate during ebb tide when fish are more concentrated near the channel bed.

Adélie Penguin Foraging Location Predicted by Tidal Regime Switching

“…Changes in penguin foraging distance and location have been observed to vary with the season [56], [57], and with daily flood and ebb tides [38]. To test for intra-seasonal changes or changes related to flood or ebb tides in the penguin location distance from Humble Is.…”

“…By comparison, the foraging location of Magellenic penguins that also inhabit the fjord rich environment of southern Chile, is best predicted by daily changes in tidal amplitude and current direction [38]. The contrast in response to tidal forces between these two penguin groups can only be understood in the light of the hydrography of their respective locations.…”

“…The impact of flood and ebb tidal forces has also influences the mode of transportation of Magellanic penguins ( Spheniscus magellanicus ), which avoid swimming against strong tidal currents by diving deeper or walking in San Julian Bay, Argentina [37]. Magellanic penguins also take advantage of tidal oscillations in the Beagle Channel, Argentina, to transport them to foraging locations maximize their foraging success [38]. The wide and varied exploitation of different tidal forces by sea birds show that tides produce regular and predictable concentrations of resources in an otherwise patchy coastal environment [39].…”

Foraging behaviour of Magellanic Penguins during the early chick‐rearing period at Isla de los Estados, Argentina

“…), longer than those observed on Martillo Island (69.6 ± 32.4 and 24.3 ± 11.8 km, trajectory and maximum distance, respectively; Raya Rey et al . , Sala et al . ), and much shorter than those observed in Penguins breeding in northern colonies (Punta Norte: 128.3 ± 39.8 and 45.4 ± 12.5 km, trajectory and maximum distance, respectively; Sala et al .…”

Social foraging European shags: GPS tracking reveals birds from neighbouring colonies have shared foraging grounds

“…In order to generate a data set of shag rafting behaviour with which to compare our GPS tracking, we conducted systematic observations of rafting birds around the archi- As animals' foraging behaviour can vary significantly depending on tidal states (Gibson 2003;Raya Rey et al 2010;Zamon 2003), for each time of day, we recorded data at three different speeds of tidal flow, in both directions (minimum, intermediate and maximum flood; minimum, intermediate and maximum ebb). The patrol sites visited each day were pseudo-randomly selected based on what combinations of site, tidal state and time of day had previously been sampled.…”