Revision 1

Accepted · first revision · record

Title: Topological or metric interactions in animal groups
Plain: A bird could respond to all neighbors within a fixed distance, or to a fixed number of nearest neighbors whatever their distance. Field data favor the second for starlings, but why the number is about seven, and whether this holds across species, is open.
Precise: Infer from 3D trajectory data the interaction kernel of birds, fish and insects: metric (range $r_c$), topological ($n_c$ nearest neighbors; $n_c \sim 6\ \mathrm{to}\ 7$ in starlings, Ballerini and co-workers, 2008) or visual-field based, using maximum-entropy or force-inference methods with model selection. Determine $n_c$ across species and the mechanism (perceptual limits, group-cohesion optimization) that sets it.
Settled by: Model selection on large trajectory data sets from several species showing which kernel fits and the measured $n_c$ or $r_c$ with uncertainties.
Kind: well-posed
Answer type: identification
References: (empty)
Literature status: partially-resolved
Status note: (empty)
Posed since: 2008