Songbird migration across the Sahara: the non-stop hypothesis rejected!

Billions of songbirds breeding in the Western Palaearctic cross the largest desert of the world, the Sahara, twice a year. While crossing Europe, the vast majority use an intermittent flight strategy, i.e.

The evolution of bird migration--a synthesis.

We approach the problem of the evolution of bird migration by asking whether migration evolves towards new breeding areas or towards survival areas in the non-breeding season. Thus, we avoid the ambiguity of the usually discussed "southern-home-theory" or "northern-home-theory". We argue that migration evolved in birds that spread to seasonal habitats through gradual dispersal to enhance survival during the non-breeding season; this in contrast to the alternative idea suggesting that migration evolved towards new breeding areas to increase reproductive success.

Stopover strategies in passerine bird migration: a simulation study.

Long-distance bird migration consists of a series of stopovers (for refuelling) and flights, with flights taking little time compared to stopovers. Therefore, it has been hypothesized that birds minimize the total time taken for migration through efficient stopover behaviour. Current optimality models for stopover include (1) the fixed expectation rule and (2) the global update rule.

Migratory directions of free-flying birds versus orientation in registration cages.

Good conditions for migration may promote offshore flights in nocturnal autumn migrants at the northern border of the Mediterranean Sea, whereas unfavourable conditions may induce flights along the coast. These predictions were tested by performing orientation cage experiments and making simultaneous observations of free-flying birds using a tracking radar. The flight directions of free-flying birds were mainly towards southwest and did not differ between overcast and clear sky conditions.

Behaviour of migrating birds exposed to X-band radar and a bright light beam.

Radar studies on bird migration assume that the transmitted electromagnetic pulses do not alter the behaviour of the birds, in spite of some worrying reports of observed disturbance. This paper shows that, in the case of the X-band radar 'Superfledermaus', no relevant changes in flight behaviour occurred, while a strong light beam provoked important changes. Large sets of routine recordings of nocturnal bird migrants obtained using an X-band tracking radar provided no indication of differing flight behaviour between birds flying at low levels towards the radar, away from it or passing it sideways.

Non-operative management of gastric perforation secondary to cardiopulmonary resuscitation.

We report the case of a 72-year-old male who suffered a cardiac arrest during an early positive treadmill stress test. After successful resuscitation the patient had evidence of a gastric perforation. Because of his hemodynamic stability, lack of peritoneal signs, and prohibitively high surgical risk, a non-operative management approach was successfully administered.