Data and code for: A delayed response in the area-concentrated search can improve foraging success

Area-concentrated search (ACS) is a simple movement rule implying that an
animal searches for resources using a 'state-dependent correlated
random walk'. Accordingly, a forager increases its searching
intensity by reducing the directionality of movement ('intensive
search mode' or ISM) when it detects a resource item, but if it
searches unsuccessfully for a while, it returns to a more straight-line
movement to search for new resource locations elsewhere ('extensive
search mode' or ESM). We propose a modified ACS, called
delayed-response ACS (dACS), which would be more efficient in resource
collection than standard ACS. Instead of immediately switching from ESM to
ISM when encountering a resource, as is done in standard ACS, an
individual foraging in the dACS mode delays this switch by 'x'
steps so it continues moving in a straight line for a while before
switching to ISM. Our results show that an individual with a suitable
delay parameter 'x' for the dACS achieves substantially higher
foraging success than an individual with standard ACS (x=0). Optimal
foraging success occurs when 'x' is approximately similar to the
patch radius 'r'. This is because, with dACS, an individual can
penetrate deeper into a cluster and stay longer within it, ultimately
increasing the number of resources collected. Modifying the
half-saturation constant 'h' also affects the success of
foraging, but the effects depend on resource density and cluster size.
Generally, 'h' modulates the optimal 'x' value only
slightly. dACS can be interpreted as a survey movement within a resource
cluster before switching from ESM to ISM. The dACS rule does not rely on
complex spatial memory but only on memorizing whether resources were found
or not. It may thus occur in a wide range of taxa, from organisms without
a central nervous system to animals with complex brain systems.