Birds arrive sequentially at their breeding ground where the nest site
s vary in value (measured by reproductive success). Each bird must eit
her choose a vacant site or challenge an occupier for its site. In the
latter case we assume the occupier to be the more likely winner. The
loser of the contest incurs a cost and must go to a vacant site. The r
ational strategy for such a contest is found. There is a threshold phe
nomenon; early arrivals occupy vacant sites, late arrivals fight. This
result is intuitively reasonable, but the sequence of sites chosen is
complex. A recursive method for specifying the solution is described
and applied explicitly to some illustrative cases. (C) 1997 Academic P
ress Limited.