Swallows' Nests*

Swallows track human moves

Most studies of the impact of humans on other species tend to be negative as more and more habitats are destroyed or degraded, so a new study provides a surprising contrast. It adds weight to the view that one of the northern hemisphere's best-loved summer visitors has vastly increased in range and numbers as a result of human activity. The barn swallow is found across North America, Europe and...

Replaceable Nests

Roosts and migrations of swallows

— Swallows of the north temperate zone display a wide variety of territorial behaviour during the breeding season, but as soon as breeding is over, they all appear to adopt a pattern of independent diurnal foraging interleaved with aggregation every night in dense roosts. Swallows generally migrate during the day, feeding on the wing. On many stretches of their annual journeys, their migrations...

Suitability of artificial nests.

Purification of erythroblastic nests.

We describe a method for preparing purified erythroblastic nests in large numbers (approximately 10(6)/run) in three steps: (1) induction of splenic erythropoiesis in mice, (2) preparative differential centrifugation for the removal of erythrocytes and single cells from spleen cell suspensions, and (3) sedimentation in an isokinetic gradient of Ficoll 400 in Joklik's modification of minimum ess...