Good vibrations: Remote-tactile foraging success of wading birds is positively affected by the water content of substrates they forage in

Some taxa of wading birds can locate buried prey by detecting vibratory
cues in their foraging substrates while probe-foraging, using a sensory
modality called “remote-touch”. As more saturated substrates transmit
vibrations better, we predict that these birds can detect prey in wetter
substrates more easily. We used sensory assays to test whether substrate
water content affects the remote-touch foraging success rate of Hadeda
Ibises, Bostrychia hagedash. The birds were more successful at locating
prey using vibratory cues than when relying on random direct contact with
the beak alone. Their remote-touch foraging success rate was positively
affected by increasing water contents of the soil, but water content had
no effect on their direct contact foraging success (indicating this is not
an artefact of ease of probing). This may partially explain the link
between the range expansion of this species in southern Africa and
increased soil irrigation, as it is easier for the birds to detect prey in
wetter substrates. Thus, it is likely that the distribution of other
remote-touch foraging birds is affected by substrate water content, and as
many of these species are endangered and rely on sensitive wetland
habitats, it is vital to understand their sensory requirements for
foraging.