Secondly, as a number of studies suggest that carotenoids could affect the modulation of sexual signals by plasma levels of the steroid hormone testosterone (T), we used the same birds to subsequently investigate whether carotenoid availability affects the increase in (nestbox-oriented) song rate induced by experimentally elevated plasma T levels.
Nonetheless, an important caveat to consider is that in order to be able to use the same birds in both the pair- and solo-training conditions, we necessarily had to train them from 2 different sites for our 2 treatments, making it essential to conduct further tests to rule out the effect of release site on the group differences in the speed and accuracy of learning we detected.
To test whether more closely related mitochondrial genomes could be separated in the same way, the exercise was repeated using the same human, bird, and snail mitochondrial genomes, together with a Norway rat (accession number AJ428514) and reef squid.
The only study so far dealing with changes in individual responses did not find evidence for a consistent short-term individual habituation to human disturbance in rural birds, using the same burrowing owl population included in this study [15].
Authorities culled 600,000 birds using the same method that had been employed in Israel.
Using the same scalpel for dissecting different birds is a possible explanation.
More fundamentally, we show that replicated maps constructed using the same SNPs reveal new insight into bird karyotype evolution; in particular a hitherto undetected degree of fine scale heterochiasmy that opens up an exciting new opportunity to study the evolution and fitness consequences of heterochiasmy.
This suggests that birds may be using the same cues from the trees as invertebrate predators and parasitoids, and that plants may not have specific adaptations for signalling just to birds.
After their performance on three-term sequence training with five examples had become stable, the birds were retested using the same "random test" described above.
All ticks were sampled from as many individual host birds as possible (average 1.3 ± 0.1 ticks per bird) and were stored using the same procedures.
