Dataset: Uca pugilator: herd position proportion

U. pugilator (those with the daily upper and lower extremes of searching space as measured above) were returned to the field within 24 hours of the first interactions during low tide, and were released into pre-existing herds of conspecifics that were foraging on the exposed mudflats at North Inlet Estuary (33°19’36.83”N, 79°12’23.76”W) in Georgetown, South Carolina, USA.

All individuals on a given day were released back onto the mudflat at the same moment by placing them all under a single cover and then raising this cover up remotely. After disturbing the herds during initial setup, we remained motionless until fiddler crabs within the herd resumed their feeding behavior prior to lifting the cover to release the marked crabs. The number of released crabs in one session ranged from four to six fiddler crabs. Following release, we assessed the location of each marked crab within the herd (edge vs. center) every three minutes by observing the crabs from a close proximity (though from a sufficient distance so as not to disturb the herd) using binoculars. An individual was tracked using its sex and carapace color as indicators for specific crab identification. The location assessment of the marked crab was characterized by the individual’s position (edge vs. center) within the herd. These observations took place every three minutes for one hour or until all marked U. pugilator were lost from sight (38.71 min ± 9.39 min, mean ± SD).