Once retrieved, the results stunned the researchers, showing the incredible achievements of these small birds (their average weight is only 40 grams):
a) most pallid swifts left the breeding colony at the Gibraltar National Museum in August and returned the following March/April. They spent this time in Africa and remained airborne throughout, even sleeping on the wing.
b) pallid swifts spent a long period (August to November) in the Sahel Region (15o-20o N), south of the Sahara Desert, before heading further south into the rain forest (0o-10o N) where they remained until the following March/April. In the rain forest, pallid swifts reached as far as Cameroun, the Republic of Congo and the Central African Republic in the east, and between Senegal and Ghana in the west. From the rain forest they returned directly back to Gibraltar in a matter of days. These results are breaking the traditional mould of birds travelling between breeding homes to specific winter quarters. They show, instead, that the idea of a single winter home does not apply, in the case of these swifts at least.
c) the remarkable crossing of the Sahara Desert was monitored on a 4-hour basis in a single swift, which managed to cross in just over one day of continuous day- and night-flying. This bird started the desert crossing at 1700 hours on the 14th August and completed the crossing by 2300 hours on the 15th August.
d) one bird showed that it went to the same areas of Africa at the same time of year in both years. This reveals an incredible ability to find the same areas of airspace over Africa from one year to the next.