Underwater visibility constrains the foraging behaviour of a diving pelagic seabird

Abstract

Understanding the sensory ecology of species is vital if we are to predict how they will function in a changing environment. Visual cues are fundamentally important for many predators when detecting and capturing prey. However, many marine areas have become more turbid through processes influenced by climate change, potentially affecting the ability of marine predators to detect prey. We performed the first study that directly relates a pelagic seabird species's foraging behaviour to oceanic turbidity. We collected biologging data from 79 foraging trips and 5472 dives of a visually dependent, pursuit-diving seabird, the Manx shearwater ( Puffinus puffinus ). Foraging behaviour was modelled against environmental variables affecting underwater visibility, including water turbidity, cloud cover and solar angle. Shearwaters were more likely to initiate area-restricted search and foraging dives in clearer waters. Underwater visibility also strongly predicted dive rate and depth, suggesting that fine-scale prey capture was constrained by the detectability of prey underwater. Our novel use of dynamic descriptors of underwater visibility suggests that visual cues are vital for underwater foraging. Our data indicate that climate change could negatively impact seabird populations by making prey more difficult to detect, compounded by the widely reported effects of reduced prey populations.

Automatic recording of rare behaviors of wild animals using video bio-loggers with on-board light-weight outlier detector

“…Performing shallow dipping to confirm the location of fish schools before diving can reduce energy consumption and increase the probability of successful foraging. Given that underwater visibility influences the foraging behavior and success of seabirds ( 32 ), the number of dips might vary based on weather conditions and water turbidity. Streaked shearwaters might employ surface dives, plunge dives, and deep dipping in relation to the accessibility of prey.…”

Decoding Ten Years of Little Penguin Foraging: Bio-Logging Reveals Foraging Patterns with Implications for Climate Change Mitigation and Marine Spatial Planning

“…High turbidity in coastal waters can also result from human-induced activities, freshwater inflow, or wind-driven resuspension of sediments (Arendt et al 2011;Ortega et al 2020), which is known to enhance productivity (Kowalczyk et al 2015). Marine predators, as little penguins, can use various sensory cues to detect and hunt their prey in turbid or dark waters (Davis et al 1999;Darby et al 2022). The effect of water visibility/turbidity on prey detection and foraging in aquatic systems supports contrasting theories depending on foraging strategies and type of prey hunted.…”

“…Temperature above the 19-21 °C range can reduce foraging success (Carroll et al 2016). Water turbidity might make prey more difficult to detect if these marine predators rely on visual cues for detecting and capturing their prey (Kowalczyk et al 2015), as in shallow diving seabirds such as shearwaters (Darby et al 2022). Overall, how these environmental conditions drive the spatio-temporal variability in foraging intensity across breeding seasons and stages is not known.…”

A new biologging approach reveals unique flightless molt strategies of Atlantic puffins

“…Molt may have prevented them from escaping the storm when they were flightless, during which they clearly struggled to find food. Similar to other diving seabirds, puffins' feeding strategy and functional dive depth may vary depending on environmental conditions (Darby et al, 2022 ), which would help to explain their highly varied diet (Baillie & Jones, 2004 ), especially during the winter, when adverse weather conditions are most likely to impact their foraging behavior (Falk et al, 1992 ; Harris, Leopold, et al, 2015 ).…”