Search results
Results from the WOW.Com Content Network
Variety is defined in the code as follows: "Variety (varietas) the category in the botanical nomenclatural hierarchy between species and form (forma)". The code acknowledges the other usage as follows: "term used in some national and international legislation for a clearly distinguishable taxon below the rank of species; generally, in ...
A taxonomist decides whether to recognize a subspecies. A common criterion for recognizing two distinct populations as subspecies rather than full species is the ability of them to interbreed even if some male offspring may be sterile. [4] In the wild, subspecies do not interbreed due to geographic isolation or sexual selection. The differences ...
The behavior spreads among the birds by imitation. [10] In captivity some will spontaneously dance to music with a variety of unique moves. [11] These birds are very long-lived, and can live upwards of 70 years in captivity, [12] [13] although they only live to about 20–40 years in the wild.
Today, it is treated as a single species with four subspecies. Along with the nominate subspecies A. g. guarauna, A. g. dolosus, A. g. elucus (both J. L. Peters, 1925), and A. g. pictus (F. A. A. Meyer, 1794) are recognized. The difference between the subspecies are related to slight differences in size and plumage. [6]
The differences between subspecies are small, making subspecific boundaries hard to define, and the exact distribution of S. a. heineken is unclear, since birds from northwest Africa may be of this form. [13] About 2% of male blackcaps on Madeira and the Azores are melanistic, with black plumage on the whole head and upper breast. [14]
There are subtle differences in colouration among subspecies, described below. Juvenile golden eagles are similar to adults but tend to be darker, appearing black on the back especially in East Asia. They have a less faded colour. Young birds are white for about two-thirds of their tail length, ending with a broad, black band. [36]
Birds have evolved a variety of mating behaviours, with the peacock tail being perhaps the most famous example of sexual selection and the Fisherian runaway. Commonly occurring sexual dimorphisms such as size and colour differences are energetically costly attributes that signal competitive breeding situations. [ 255 ]
For species found in the 50 states, Puerto Rico, and the U.S. Virgin Islands, the taxonomic treatment (designation and sequence of orders, families and species) and nomenclature (common and scientific names) used in the list are those of the AOS, the recognized scientific authority on the taxonomy and nomenclature of North and Middle American birds.