Behavioral Response of Corophium volutator to Shorebird Predation in the Upper Bay of Fundy, Canada

Abstract

Predator avoidance is an important component of predator-prey relationships and can affect prey availability for foraging animals. Each summer, the burrow-dwelling amphipod Corophium volutator is heavily preyed upon by Semipalmated Sandpipers (Calidris pusilla) on mudflats in the upper Bay of Fundy, Canada. We conducted three complementary studies to determine if adult C. volutator exhibit predator avoidance behavior in the presence of sandpipers. In a field experiment, we monitored vertical distribution of C. volutator adults in bird exclosures and adjacent control plots before sandpipers arrived and during their stopover. We also made polymer resin casts of C. volutator burrows in the field throughout the summer. Finally, we simulated shorebird pecking in a lab experiment and observed C. volutator behavior in their burrows. C. volutator adults were generally distributed deeper in the sediment later in the summer (after sandpipers arrived). In August, this response was detectably stronger in areas exposed to bird predation than in bird exclosures. During peak predator abundance, many C. volutator adults were beyond the reach of feeding sandpipers (>1.5 cm deep). However, burrow depth did not change significantly throughout the summer. Detailed behavioral observations indicated that C. volutator spent more time at the bottom of their burrow when exposed to a simulated predator compared to controls. This observed redistribution suggests that C. volutator adults move deeper into their burrows as an anti-predator response to the presence of sandpipers. This work has implications for predators that feed on burrow-dwelling invertebrates in soft-sediment ecosystems, as density may not accurately estimate prey availability.

Biological and biogeochemical methods for estimating bioirrigation: a case study in the Oosterschelde estuary

“…Furthermore, Wrede et al (2018) suggested including a temperature correction factor (Q 10 ) in the calculations to account for the expected metabolic response of macrofauna to increasing water temperatures (Brey, 2010). This temperature effect on benthic activity has indeed been noticed in similar works (Magni and Montani, 2006;Rao et al, 2014), but in our study and others the highest temperatures were not clearly associated with the highest functional process rates (Schlüter et al, 2000;Braeckman et al, 2010;Queirios et al, 2015). The reasons for this ranged from a noncoincidence of the annual food pulse and the temperature peak to the presence of confounding factors in the analysis such as faunal abundances and behavior (Forster et al, 2003).…”

“…Intertidal areas also experience stronger variations in physical stressors such as waves, temperature, light, salinity and precipitation than subtidal areas do (Herman et al, 2001) and are more subject to biological stressors such as predation by birds (Fleischer, 1983;Granadeiro et al, 2006;Ponsero et al, 2016). Burrowing more deeply or simply residing in deeper sediment layers for a longer time are valid strategies for species in the intertidal areas to combat these pressures (Koo et al, 2007;MacDonald et al, 2014).…”

Biological and biogeochemical methods for estimating bio-irrigation: a case study in the Oosterschelde estuary

“…Intertidal areas experience stronger variations in physical stressors such as waves, temperature, light, salinity and precipitation than subtidal areas (Herman et al, 2001), and to biological stressors such as predation by birds (Fleischer, 1983;Granadeiro et al, 2006;Ponsero et al, 2016). Burrowing deeper, or simply residing in deeper sediment layers for a longer time, are valid strategies for species in the intertidal to combat these pressures (Koo et al, 2007;MacDonald et al, 2014).…”

Effect of forager density on feeding rates in spring-staging Semipalmated Sandpipers (Calidrispusilla) using different foraging modes

“…Interference through prey depression was detected in redshank pecking for amphipods, but not in redshank and bar-tailed godwit (Limosa lapponica (L., 1758)) probing for annelids (Goss-Custard 1976;Selman and Goss-Custard 1988;Yates et al 2000;Minderman et al 2006). This is because amphipods, C. volutator and Orchestia spp., which are commonly preyed upon by shorebirds, in the presence of predators reposition themselves from mud surface deeper into their burrows, thus becoming temporarily less available to birds that are feeding by sight (Goss-Custard 1976;Minderman et al 2006;MacDonald et al 2014). The average response distance of C. volutator, at which they retreat deeper into the sediment in the presence of redshank, is 0.6 m (range 0.1 to 1 m) (Stillman et al 2000).…”