Mountain pygmy owl

Last updated

Mountain pygmy owl
Mountain Pygmy Owl Glaucidium gnoma Arizona.jpg
CITES Appendix II (CITES) [2]
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Strigiformes
Family: Strigidae
Genus: Glaucidium
Species:
G. gnoma
Binomial name
Glaucidium gnoma
Wagler, 1832
Glaucidium gnoma map.svg

The mountain pygmy owl or northern pygmy owl (Glaucidium gnoma) is a small species of owl from the family Strigidae. They reside throughout southern Arizona, New Mexico and Mexico.

Contents

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 concern, the increase in deforestation could impact the future population.

Taxonomy

The taxonomy of the pygmy owl genus, ( Glaucidium ), remains disputed amongst taxonomic authorities. The International Ornithologists' Union, considers the mountain pygmy owl (Glaucidium gnoma) to be a separate species from the Northern pygmy owl (Glaucidium californicum). [3] Whereas, the American Ornithological Society has amalgamated the mountain, Guatemalan ( Glaucidium cobanense), Baja ( Glaucidium hoskinsi ) and northern pygmy owl, as the same species (conspecific) and classifies them all under Glaucidium gnoma and further categorizes them into respective subspecies. [4] This northern pygmy owl complex ranges from North America to Central America. [4] However, individuals inhabiting these regions demonstrate unique vocal patterns, indicating distinct species and population distribution. [4] Although more research is required, genetic sequencing based on cytochrome b and nuclear markers suggests that Glaucidium gnoma and Glaucidium californicum are not conspecific. [4] [5]

Description

The adult mountain pygmy owl is approximately 15–17 cm (5.9–6.7 in) in length. [5] Males weigh from 48 to 54 g (1.7–1.9 oz); however, reverse sexual dimorphism indicates that adult females are larger in mass reaching 60 to 73 g (2.1–2.6 oz). [5] The wing length of a male is 86–89 mm (3.4–3.5 in) and that of 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). [5] [6]

Adult plumage colour is similar to that of most pygmy owls. The chest and throat are white, while the face is a deeper brown. [7] 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. [7] 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. [7] Visible on the underside of the tail are 3 to 4 alternating bars. [7] 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. [7]

The plumage of nestlings (chicks) consists of whitish natal down feathers. [5] Within a few weeks, their second layer of down feathers starts to appear. The fledgling (juvenile) plumage resembles that of the adult pygmy owl. [5] 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. [5]

Visual identification

The individuals within the northern pygmy owl complex, although similar, each have their own characteristics used for identification. The mountain pygmy owl is small, with a short tail and slightly pointed wing-tips, [8] in comparison to the northern pygmy owl, which is larger in stature with rounded wing-tips and a longer tail. [8] The Guatemalan pygmy owl is distinguished by its vibrant red-brown plumage and white centre tail bars surrounded by a dark trim. [8] The Baja pygmy owl is also small in size, similar to the mountain pygmy owl: however, it has rounded wing-tips like that of the northern pygmy owl. In addition, its throat is white in colour. [8]

Habitat and distribution

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. [5] Although, forests primarily composed of Ponderosa pines are preferential, as the reduced forest understory facilitates their hunting behaviours. [8]

The species is distributed from southern Arizona and New Mexico to Oaxaca in southern Mexico. [5]

Behaviour

Individuals within the northern pygmy owl complex demonstrate similar behaviours; they are known to be aggressive, and relatively unsocial when compared to other owl species. [7] [8] They prefer to live alone, when not engaging in breeding pairs. [8]

Vocalization

There is limited information regarding specific seasonal calls or songs, pertaining to the mountain pygmy owl. However, it is suggested that vocal behaviour observed in the Eurasian pygmy owl, ( Glaucidium passerinum ), can be applied to the other pygmy owl species. [8] Pygmy owls from British Columbia to California have a slow single hoot, compared to pygmy owls in southern British Columbia which have a slow double hoot. Individuals in the interior United States to Arizona have a fast single hoot, and a fast double hoot can be heard from southern Arizona to southern Mexico. [7] Calls consist of two categories, primary and secondary. Territorial calls are considered primary and consist of an echoed single and or double "hooting/tooting", which can be heard close to sunrise and after sunset throughout the year. These calls can be heard more frequently in spring and fall. [8] In addition, during nesting season, the male will call ahead with a soft hoot, when approaching the nesting cavity with food. The female has a similar but broken call, which she uses in communication with the male and when in danger. [8] A form of duetting can be heard, where the male will hoot first and the female will answer in a lower tone. The secondary call is a song of increasing pitch that consists of 11 hoots. [8] This call can be heard from both males and females, throughout the year. Furthermore, it is more frequent during autumn, when they are protecting their territory and encouraging their young to leave the nest. [8]

Diet and hunting

The diet of the mountain pygmy owl consists of the following: insects, orthopterans (crickets, grasshoppers), beetles, small mammals (rodents) and reptiles. [5] Their diet consists of a large portion of songbirds including the American robins and larger species. [9] [7]

Pygmy owls have a rather unique feeding habit, as they can consecutively consume prey head first. [8] However, when consuming snakes, they do so tail first. They have a very high metabolism and require a constant food supply. [8] 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. [8]

The pygmy owl is a diurnal hunter but is also known to hunt around dawn and dusk. [8] Interestingly, when in flight, the wings of the pygmy owl make noise, unlike other owl species which are silent fliers. [8] While perching on a high branch it will search for prey, and 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 grounds. [8] The reason for this behaviour is that the pygmy owl is commonly mobbed by songbirds. [5] [8] This is a form of defence, where multiple songbirds will swarm a predator forcing them to leave the area.

Movement

This species is mainly residential, as they do not migrate. [10] The further northern pygmy owl species have a limited winter migration, descending from mountain regions to closer lowlands. [8]

Reproduction

Little has been observed regarding the social behaviour and reproduction of the mountain pygmy owl. Data is available from the Eurasian pygmy owl, which may be generalized and applied to the Northern pygmy complex. [8] Sexual maturity can commence at 5 months of age, followed by breeding at the age of 1 year. [8] Pygmy owls form monogamous pairs, usually spanning one breeding season. Though, a pairing could return to the same nesting location for up to four years. [8] 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. [8] Duet singing decreases when the male demonstrates nesting behaviour. [8] Nests are formed in either hollowed tree cavities or woodpecker holes. [5] 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. [8]

Mountain pygmy owls lay eggs between May 19 to June 14. [8] Clutches range from 2 to 4 white eggs, which are laid at the base of the nest. [5] The female will commence the approximately 28-day incubation period, once all the eggs have been laid. This would explain why chicks hatch within a short period of each other. [8] 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. [8] An estimated 14 days after hatching, the nestlings have attained approximately 60% of their mature weight. [8] 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. [8] The parental pair will remain in the vicinity of the nest, and provide protection for upwards of 20-30 additional days. [8]

Grooming

The practice of preening (grooming) is demonstrated across all owl species. They clean their feathers and remove foreign debris by carefully passing the feather through their partially open bill. [8] Waterproofing of feathers is obtained by using their beak to spread the oil from their uropygial gland. This gland is located on the outer-side of the body, at the start of the tail. [8] Facial feathers are maintained by the owl using its talons. Within breeding pairs, allopreening (i.e., both owls clean each other) has also been observed in members of the northern pygmy owl complex. [8]

Conservation

According to the International Union for Conservation of Nature (IUCN) the mountain pygmy owl is categorized as a least-concern species. [11] However, the species is suspected to be declining in population due to habitat loss, from deforestation and fragmentation. [5] [11]

Related Research Articles

<span class="mw-page-title-main">Barn owl</span> Common cosmopolitan owl species

The barn owl is the most widely distributed species of owl in the world and one of the most widespread of all species of birds, being found almost everywhere except for polar and desert regions, Asia north of the Himalayas, some islands of Indonesia, and some Pacific Islands. It is also known as the common barn owl, to distinguish it from the other species in its family, Tytonidae, which forms one of the two main lineages of living owls, the other being the typical owls (Strigidae).

<span class="mw-page-title-main">Eurasian pygmy owl</span> Species of owl

The Eurasian pygmy owl is the smallest owl in Europe. It is a dark reddish to greyish-brown, with spotted sides and half of a white ring around the back of the neck. This species is found in the boreal forests of Northern and Central Europe to Siberia.

<span class="mw-page-title-main">Northern saw-whet owl</span> Species of owl

The northern saw-whet owl is a species of small owl in the family Strigidae. The species is native to North America. Saw-whet owls of the genus Aegolius are some of the smallest owl species in North America. They can be found in dense thickets, often at eye level, although they can also be found some 20 ft (6.1 m) up. Saw-whets are often in danger of being preyed upon by larger birds of prey. The northern saw-whet owl is a migratory bird without any strict pattern.

<span class="mw-page-title-main">Violet-green swallow</span> Species of bird

The violet-green swallow is a small North American passerine bird in the swallow family. These aerial insectivores are distributed along the west coast from Alaska to Mexico, extending as far east as Montana and Texas. With an appearance very similar to the tree swallow, these individuals can be identified by the white rump side-patches that appear to separate their green back and purple tail. Violet-green swallows are secondary cavity nesters, found in a number of habitats including deciduous and coniferous forest. In addition to nesting in tree holes within these habitats, they are also widely observed nesting in the cracks of large cliffs.

<span class="mw-page-title-main">Pearl-spotted owlet</span> Species of owl

The pearl-spotted owlet is a small bird of prey found in sub-Saharan Africa. They belong to the Strigidae family, otherwise known as the typical owls or the true owls, which contains most species of owl. As part of the genus Glaucidium, or pygmy owls, they are commonly referred to as 'owlets' due to their diminutive size. Pearl-spotted owlets are brownish and heavily spotted white, with two distinct black false 'eyes' at the back of their head. They are often confused with an African barred owlet.

<span class="mw-page-title-main">Flammulated owl</span> Species of owl

The flammulated owl is a small migratory North American owl in the family Strigidae. It is the only species placed in the genus Psiloscops.

<span class="mw-page-title-main">Square-tailed kite</span> Species of bird

The square-tailed kite is a medium-sized bird of prey in the family Accipitridae, which also includes many other diurnal raptors such as kites, eagles and harriers.

<span class="mw-page-title-main">Powerful owl</span> Species of owl

The powerful owl, a species of owl native to south-eastern and eastern Australia, is the largest owl on the continent. It is found in coastal areas and in the Great Dividing Range, rarely more than 200 km (120 mi) inland. The IUCN Red List of Threatened Species also refers to this species as the powerful boobook.

<span class="mw-page-title-main">Northern pygmy owl</span> Species of owl

The northern pygmy owl is a small owl native to western North America.

<span class="mw-page-title-main">Cape eagle-owl</span> Species of owl

The Cape eagle-owl is a species of owl in the family Strigidae. It is one of several large species of the eagle-owl genus Bubo.

<span class="mw-page-title-main">Barred eagle-owl</span> Species of owl

The barred eagle-owl, also called the Malay eagle-owl, is a species of eagle owl in the family Strigidae. It is a member of the large genus Ketupa which is distributed on most of the world's continents. This relatively little-known species is found from the southern Malay Peninsula down a string of several of the larger southeast Asian islands to as far as Borneo. It forms a superspecies with the physically similar but larger spot-bellied eagle-owl, although the two species appear to be allopatric in distribution.

<span class="mw-page-title-main">Asian barred owlet</span> Species of owl

The Asian Barred Owlet also known as the Cuckoo owlet is a species of pygmy owl native to the forests and shrublands of mainland Southeast Asia to the foothills of the Himalayas of northern Pakistan. It is a smaller owl, measuring 22–25 cm (8.7–9.8 in) making it one of the larger pygmy owls. They are primarily insectivorous but will eat lizards, small rodents and birds as well.

<span class="mw-page-title-main">Cloud-forest pygmy owl</span> Species of owl

The cloud-forest pygmy owl is a short, muscular, small-sized species of owl found throughout the Andes of western Colombia and north-western Ecuador, being confined to cloud forests between 900–2000 m a.s.l. Below this altitudinal range the Central American pygmy owl occurs; above it, the Andean pygmy owl occurs.

<span class="mw-page-title-main">Colima pygmy owl</span> Species of owl

The Colima pygmy owl is a species of owl in the family Strigidae. It is endemic to the western part of Mexico.

<span class="mw-page-title-main">Pacific pygmy owl</span> Species of owl

The Pacific pygmy owl or Peruvian pygmy owl is a small "typical owl" in subfamily Surniinae. It is found in Chile, Ecuador, and Peru.

<span class="mw-page-title-main">Tamaulipas pygmy owl</span> Species of owl

The Tamaulipas pygmy owl is a species of owl in the family Strigidae. It is endemic to Mexico. This is one of the smallest owls in the world, with a mean length of 13.5 cm (5.3 in). However, at 53 g (1.9 oz), it is slightly heavier than the long-whiskered owlet and the elf owl. Its natural habitat is subtropical or tropical moist montane forests.

<span class="mw-page-title-main">Cuban pygmy owl</span> Species of owl

The Cuban pygmy owl is a species of owl in the family Strigidae that is endemic to Cuba.

<span class="mw-page-title-main">White-tipped quetzal</span> Species of bird

The white-tipped quetzal is a species of bird in the family Trogonidae found in Venezuela, Colombia, and Guyana. Two subspecies have been described. Pharomachrus fulgidus fulgidus is found in the mountains of northern Venezuela and Pharomachrus fulgidus festatus ranges through the Santa Marta mountains of northeast Colombia. Quetzals are iridescent and colourful birds found in forests, woodlands and humid highlands. The white-tipped quetzal has been a limited subject of research. Pharomachrus nests have been studied to analyse the effects of rainfall on breeding, however conclusions are based on single observations. On the IUCN Red list of threatened species, the white-tipped quetzal is listed as a species of least concern.

<span class="mw-page-title-main">Baja pygmy owl</span> Species of owl

The Baja pygmy owl or cape pygmy owl, is a subspecies of northern pygmy owl restricted to the Mexican state of Baja California Sur. Although some taxonomists, including the International Ornithologists' Union, consider it to be a distinct species, other authorities, including the American Ornithological Society, do not consider it separate, and consider it to be a subspecies of the northern pygmy owl.

<span class="mw-page-title-main">Guatemalan pygmy owl</span> Species of owl

The Guatemalan pygmy owl is a small "typical owl" in subfamily Surniinae. However, some taxonomic systems consider it to be a subspecies of northern pygmy owl. It is found in Mexico, Guatemala, and Honduras.

References

  1. ↑ BirdLife International (2016). "Glaucidium gnoma". The IUCN Red List of Threatened Species . 2016. IUCN: e.T61791135A95180896. doi: 10.2305/IUCN.UK.2016-3.RLTS.T61791135A95180896.en . Retrieved 15 January 2018.
  2. ↑ "Appendices | CITES". cites.org. Retrieved 2022-01-14.
  3. ↑ "BOW (Birds of the World) – IOC World Bird List" . Retrieved 2021-11-12.
  4. 1 2 3 4 Eisermann, Knut; Howell, Steve N. G. (2011). "Vocalizations of the Guatemalan Pygmy-Owl (Glaucidium cobanense)". Journal of Raptor Research. 45 (4): 304–314. doi:10.3356/JRR-10-73.1. ISSN   0892-1016. S2CID   85043440.
  5. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 König, Klaus (2008). Owls of the world. Friedhelm Weick, Michael Wink (2nd ed.). London: Christopher Helm. pp. 43, 50, 162, 397, 398. ISBN   978-1-4081-3578-5. OCLC   769189719.
  6. ↑ Deshler, John F. (2021-04-28). "Higher reversed sexual size dimorphism among nesting pairs of Northern Pygmy-Owls (Glaucidium gnoma) in northwestern Oregon than among specimens collected at the range-wide scale". The Wilson Journal of Ornithology. 132 (3). doi:10.1676/19-132. ISSN   1559-4491. S2CID   233429944.
  7. 1 2 3 4 5 6 7 8 Howell, Steve N. G. (1995). A guide to the birds of Mexico and northern Central America. Sophie Webb. Oxford: Oxford University Press. pp. 360, 361. ISBN   0-19-854013-2. OCLC   28799888.
  8. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 Johnsgard, Paul A. (2002). North American owls : biology and natural history (2nd ed.). Washington, D.C.: Smithsonian Institution Press. pp. 33, 35, 139, 140, 142, 141, 143, 144. ISBN   1-56098-939-4. OCLC   48943959.
  9. ↑ Hayward, G. D.; Garton, E. O. (1988). "Resource partitioning among forest owls in the River of No Return Wilderness, Idaho". Oecologia. 75 (2): 253–265. Bibcode:1988Oecol..75..253H. doi:10.1007/BF00378606. ISSN   0029-8549. PMID   28310843. S2CID   23481481.
  10. ↑ König, Claus (1999). Owls : a guide to the owls of the world. Friedhelm Weick, J. H. Becking. New Haven: Yale University Press. p. 356. ISBN   0-300-07920-6. OCLC   42890802.
  11. 1 2 International), BirdLife International (BirdLife (2016-10-01). "IUCN Red List of Threatened Species: Glaucidium gnoma". IUCN Red List of Threatened Species. doi: 10.2305/iucn.uk.2016-3.rlts.t61791135a95180896.en .
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.