The smallest species is believed to be the Black-thighed Falconet, small males of which can weigh only 28 g (1 oz), measure 14 cm (5.5 inches) and have a wingspan of 26 cm (10.3 inches).
Birds (except Falconiformes) usually have karyotypes of approximately 80 chromosomes (2n = 80), with only a few being distinguishable macrochromosomes and an average of 60 being microchromosomes.
The existing avifauna can be grouped into podicipediformes, pelecaniformes, phoenicopteriformes, falconiformes, anseriformes, galliformes, gruiformes, charadriiformes, columbiformes, cuculiformes, strigiformes, caprimulgiformes, apodiformes, coraciiformes, piciformes, passeriformes. 39 species are included in the Red Book of Armenia.