The fact that the leading-edge vortex also enhances the flight of insects, bats (ScienceNOW, 10 May 2007), and probably birds indicates that it is an important universal mechanism for generating high lift forces, says Anders Hedenström, a theoretical ecologist at Lund University in Sweden.
The fact that the birds put on weight during their foraging trips and returned after a similar period to other, control birds, indicates that the TDRs had little impact on their performance.
The clear directional compensation found even in experimentally displaced birds indicates that first-year birds can also possess the ability to correct for displacement in some circumstances, possibly involving either some primitive form of true navigation, or 'sign posts', but the cues used for this are highly speculative.
The delayed growth in our birds indicates that our experimental protocol clearly affected the overall development of the young, and it is conceivable that this impact also extended to the development of the birds' brains.
According to their findings, which were just published in the journal, Science, young captive-bred whooping cranes perform better when migrating in the presence of older, more experienced birds, indicating that "instinct" is not enough for efficient and accurate migration.
Investigations of thermoreception and thermoregulation in birds indicate that thermosensors exist not only in the skin on the body but also in the skin around the face, the thoracic brood patch (the area used for egg incubation), and the beak.
Lawrence M. Witmer, a paleontologist at Ohio University who conducts other Archaeopteryx research, said that he was not surprised to learn that the species was "not fully avian," but that it had many features seen in later birds, indicating that it had not been displaced as "a very basal member" of the avian family tree.
The mate choice tests with adult birds indicate that nutritional conditions during the period of song learning, brain and gonad development, and moult into adult plumage have persisting effects on male attractiveness.
No significant difference was found between summer and winter birds indicating that they were carrying the additional fat at no additional energetic cost (Figure 1b, ANCOVA: season, F1,64 = 2.81, r2 = 0.025, p = 0.100; U, F1,64 = 47.7, r2 = 0.42, p<0.001).
Experiments with captive birds indicate that the availability of calcium [15]; see also [16], phenylalanine and tyrosine [17] could be limiting for the production of melanins see also [18].
When comparing the total number of birds infested with infected ticks compared to the total number of collected birds, the figures were 59/6174 = 1% in ground-foraging birds and 18/7085 = 0.25% in other birds indicating that the former group of birds has a higher risk of exposure to ticks as a result of their feeding habits [Fisher's exact test, p<0.001].
