Showing papers by "Miguel Ferrer published in 1993"
TL;DR: Investigation of factors influencing dispersal distances in 30 young Spanish imperial eagles radio-tagged in southwestern Spain in 1986–1990 found that birds that hatched earlier and that had lower blood urea levels had longer displacements, indicating that better-nourished young had better displacements.
Abstract: I studied factors influencing dispersal distances in 30 young Spanish imperial eagles (Aquila adalberti) radio-tagged in southwestern Spain in 1986–1990. The mean dispersal distance between the natal nest and the settling area was 138 km. Every young bird reached its maximum dispersal distance within 4 months of its departure from the natal population. No significant differences between the sexes were detected in maximum dispersal distance, but females spent more time in the more distant settling areas. Dispersal distance was not related to the date of departure from the natal population. Dispersal distance was significantly longer for birds that hatched earlier and that had lower blood urea levels, indicating that better-nourished young had longer displacements. These results are not in accordance with the competitive displacement hypothesis.
78 citations
01 Jan 1993
56 citations
30 citations
TL;DR: Blood chemistry values in Pygoscelis penguins were essentially similar to those described in other bird groups, and there has not been any apparent variation in penguins normal values that could be interpreted as an adaptation to Antarctic special environmental conditions.
22 citations
17 citations
TL;DR: In this article, two adoptions in Spanish Emperial eagle were recorded involving 5.5 % of the fledglings and the results of blood analyses show that values of the adopted fled chicks were not the highest for variables indicative of chronic malnutrition, which supports the view that adoptions result from the unusual proximity between nests.
Abstract: From 1986 to 1989 two adoptions in Spanish Emperial Eagle were recorded involving 5.5 % of the fledglings. The results of blood analyses show that values of the adopted fledglings were not the highest for variables indicative of chronic malnutrition. Both adoptions involved nests nearest to one another. These observations support the view that adoptions result from the unusual proximity between nests.
12 citations