The mountain pygmy owl (Glaucidium gnoma ) is a small species of owl from the family Strigidae. They reside throughout southern Arizona, New Mexico and Mexico.
There is current taxonomic debate regarding its classification as an independent species or subspecies from that of the northern pygmy owl. Similar plumage colour and different vocal patterns are the primary characteristics fuelling this confusion.
The mountain pygmy owl hunts for small mammals and insects during the day from its high perches in pine-forested mountains, at elevations of 1,500 to 3,500 m. Breeding occurs once the female has chosen the appropriate cavity to form her nest. The female mountain pygmy owl will lay eggs between May and June. Owlets will leave their nests 23-30 days, after hatching. Although the International Union for Conservation of Nature (IUCN), has ranked this species as least-concerned, the increase in deforestation could impact the future population.
The adult mountain pygmy owl is approximately 15–17 cm (5.9–6.7 in) in length. Males weigh between 48–54 g (1.7–1.9 oz); however, reverse sexual dimorphism indicates that adult females are larger in mass reaching between 60–73 g (2.1–2.6 oz). The wing length of a male is 86–89 mm (3.4–3.5 in) and a female is 87–98 mm (3.4–3.8 in) while the tail of both sexes can reach 61–66 mm (2.1–2.6 in).
Adult plumage colour is similar to that of most pygmy owls. The chest and throat are white, while the face is a deeper brown. The colour of the facial disk is a pale brownish-red (rufous), containing flecks of cream. In addition, their eyebrows are thin in shape and white in colour. The head, neck, wings and tail have a pale rufous base colour, with a cream spotted pattern. The exterior of the tail has 5 to 6 alternating bands of white and rufous. Whereas, visible on the underside of the tail are 3 to 4 alternating bars. The chest and underside are white with vertical, broken streaks of red-brown. The iris colour is yellow, similar to the colour of the feet and bill.
The plumage of nestlings (chicks) consists of whiteish natal down feathers. Within a few weeks, their second layer of down feathers start to appear. The fledgling (juvenile) plumage resembles that of the adult pygmy owl. However, the crown (top of head) is grey, with minimal spotting on the forehead. Moreover, the eyebrows are white, thicker and more prominent than that of the adult.
The mountain pygmy owl resides in tropical and subtropical forests of Oak, Pine and Evergreens; located in mountainous terrain at elevations from 1,500 to 3,500 m. Although, forests primarily composed of Ponderosa pines are preferential, as the reduced forest understory facilitates their hunting behaviours.
The species is distributed from southern Arizona and New Mexico to Oaxaca, part of the southern tip of Mexico.
This species is mainly residential, as they do not migrate. The further northern pygmy species have a limited winter migration, descending from mountain regions to closer lowlands.
when not engaging in breeding pairs.
This species is mainly residential, as they do not migrate. The further northern pygmy species have a limited winter migration, descending from mountain regions to closer lowlands.
The diet of the mountain pygmy owl consists of the following: insects, orthopterans (crickets, grasshopper), beetles, small mammals (rodents) and reptiles. Their diet consists of a large portion of songbirds including the American robins and larger species.
Pygmy owls have a rather unique feeding habit, as they can consecutively consume prey head first. However, when consuming snakes, they do so tail first. They have a very high metabolism and require a constant food supply. The pygmy owl's lack of a crop and inefficient gastric digestion, inhibits its ability to digest bones, thus causing the formation and regurgitation of pellets.
The pygmy owl is a diurnal hunter but is also known to hunt around dawn and dusk. Interestingly, when in flight, the wings of the pygmy owl make noise, unlike other owl species which are silent fliers. While perching on a high branch it will search for prey, once found, the pygmy owl will dive to the ground to catch it. It is significant to note that, if the attempt fails the owl will immediately search for new hunting grown's. The reason for this behaviour is that the pygmy owl is commonly mobbed by songbirds. This is a form of defence, where multiple songbirds will swarm a predator forcing them to leave the area.
Little has been observed regarding the social behaviour and reproduction of the mountain pygmy owl, data available is from the Eurasian pygmy owl, but can be generalized and applied to the Northern pygmy complex. Sexual maturity can commence at 5 months of age, followed by breeding at the age of 1 year. Pygmy owls form monogamous pairs, usually span one breeding season. Though, a pairing could return to the same nesting location for up to four years. The male displays courtship behaviour by a series of consistent hoots while jumping from branch to branch within a claimed territory. Initially, both sexes demonstrate hesitation and aggression towards each other. Duet singing decreases when the male demonstrates nesting behaviour. Nests are formed in either hollowed tree cavities or woodpecker holes. Once the male locates a possible nest, he will fly into it and inform the female via his call so that she may inspect it. The female will choose the ideal cavity and begin to clean it; copulation will occur soon after.
Mountain pygmy owls lay eggs between May 19 to June 14. Clutches range between 2 to 4 white eggs, which are laid at the base of the nest. The female will commence the approximate 28 day incubation period, once all the eggs have been laid. This would explain why chicks hatch within a short period of each other. It is thought that the mountain pygmy owl demonstrates similar feeding behaviour to that of the Eurasian pygmy owl. Once the eggs have hatched, the male mountain pygmy owl will provide more food to the female. An estimated 14 days after hatching, nestlings have attained approximately 60% of their mature weight. It has been observed in several pygmy owl species that, within a month of hatching, 23-30 days, juveniles are able to fly and will leave their nests. The parental pair will remain in the vicinity of the nest, and provided protection for upwards of 20-30 additional days.
According to the International Union for Conservation of Nature (IUCN) the mountain pygmy owl is categorized as a least-concern species. However, the species is suspected to be declining in population due to habitat loss, from deforestation and fragmentation.
