Respuesta :
Answer: They have enough food in the tropical region and are no longer searching for mates.
Explanation:
The Sanderling is a energetic, small and plump wading bird. It posses medium length legs which are black and short straight black bill. It is white underneath and pale grey above. It is native of southern UK but migrate to the coastal regions of south during spring for breeding.
According to the given situation, the members of the Sanderling population which are beyond the breeding age do not migrate as they have enough food and they have lost the tendency to copulate and search the mates.