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Douglas ground squirrel (Otospermophilus douglasii) is a rodent that has brown fur with small white spots on its head, back and flanks, with a dark patch behind and between its silvery shoulders, a lighter belly and a long, fluffy tail. It lives in colonies and makes extensive tunnels to sleep, shelter from danger, and foster its newborns. It is an important prey species for snakes, birds of prey and mammalian predators. It eats seeds, and during the growing season a variety of other parts of plants. It is regarded an agricultural pest, may cause damage to infrastructure due to its burrowing, and is considered a potential risk for human health since it harbors several infectuous diseases. It can primarily be found in grasslands and open woodlands, from the coastline to the mountains, in the states of Washington, Oregon, and northern California of the USA. In 2023, the International Union for Conservation of Nature had not yet determined the conservation assessment for Otospermophilus douglasii. Douglas ground squirrel was initially described as a species, but later considered to be a subspecies of Otospermophilus beecheyi, the California ground squirrel. However, comparison of homologous DNA suggests Douglas ground squirrel should be considered as a separate species.[1]
Description
Dougas ground squirrel can be distinguished from ground squirrel species in other genera by its light brown to cream-colored belly, the long, fluffy tail, and the white ringed eyes. The stripe along the back is darker in the Douglas ground squirrel compared to the California ground squirrel, but also by the blackish-brown triangle between the neck and halfway down the back, the light brown shoulders, and the dense, silver coloured hairs. Between shoulder and elbow, and along the tail, Dougas ground squirrel has white-tipped hairs whereas the California ground squirrel has a buffy wash on these hairs. The differences between these species are most profound in adults. The specking with white spots on the grayish brown fur on the back distinguishes Dougas ground squirrel from the rock squirrel, whose back is a mixture of grayish brown with cinnamon buff and light to dark blackish-brown. Rarely, the entire back of rock squirrel is black, which has never been observed in Dougas ground squirrels.[1]
Development
The hairless newborns have a wrinkled, red skin, have their eyes closed, have little control over their movements and weigh approximately 12 g. During the second week hair start to appear on the head and back, the skin has started to build up pigment and weight as doubled. During the fourth week, eyes begin to open, limbs are moving tand heads raised, and young weigh about 35 g. At 7 weeks old, pigmented hair has appeared throughout the body, eyes can be fully opened, movements are controlled, and te young reach about 65 g. During the eighth week, young on average are 73 g and have began taking solid food.
In central Oregon juveniles venture outside of the burrows during June, and several weeks later in northern California. Juveniles appear later on the surface at higher elevations. The animalis begin to put on body fat at the end of summer and reach their heighest weight by the end of September, preceding the start of inactivity in November (Maser et al. 1981). Although there is little activity during winter, both adults and juveniles emerge during warm or dry spells during winter (Edge 1931). Edge (1931) trapped adult females earlier in the spring than he trapped adult males. However, additional study is required to understand whether robust sex differences in activity exist in O. douglasii. In contrast, for most ground squirrels, including O. beecheyi, adult males are active above ground earlier in the spring than adult females in areas with seasonal activity patterns (Smith et al. 2016). One removal study suggested that the young of the year typically dispersed from the natal social group by the end of the summer; a small number of adults also dispersed from populations of higher densities to populations of lower densities (Stroud 1982). Discounting predation and disease, Edge (1934) estimated the maximum life span to be 5–6 years. [1]
Differences with related species
The three species of the genus Otospermophilus differ from other ground squirrel genera by the light brown to creamy belly, a long, fluffy tail, and a light ring around each of the eyes. Compared to the California ground squirrel, Douglas ground squirrel has a darker stripe along the length of its back, lighter brown shoulders, mostly with dense, silvery hairs on the sides of its neck, and a blackish-brown to charcoal-colored triangular patch that extends from the neck to about halfway down the spine. Douglas ground squirrel has white tipped hairs to the sides of the upper forelegs and the tail, while these hairs in the California ground squirrel have a buffy wash. These differences are most apparent in adult individuals and much less conspicuous in juveniles. Douglas ground squirrels can be distinguished from the rock squirrel because of the speckling of white spots over the grayish brown coat on its back. The rock squirrel on the other hand often also has a grayish brown back but combined with mix of cinnamon buff and light brown to bone to dark blackish-brown, and sometimes rock squirrels have an entirely back black.[1]
Taxonomy
Douglas ground squirrel, found on the banks of the Columbia River was first scientifically described by John Richardson in his book Fauna Boreali-Americana of the zoology of the northern parts of British America, published in 1829, and called it Arctomys (Spermophilus) douglasii. The famous French paleontologist, geologist and naturalist George Cuvier suggested in 1831 to place the ground squirrels in a genus separate from the groundhog, creating the new combination Spermophilus douglasii. In 1874 Joel Asaph Allen regarded Douglas ground squirrel as a variety of the rock squirrel and made the new combination Spermophilus grammurus var. douglasi, incorrectly spelling the species name. Walter Pierce Bryant also made a mistake in copying Richardson's species name, so creating Spermophilus grammurus douglassi. In 1901, Daniel Giraud Elliot placed Douglas ground squirrel in a new subgenus and so compounded the name Spermophilus (Otospermophilus) grammurus douglasi, again an erroneous spelling. In 1903, Elliot moved Douglas ground squirrel along with the rock squirrel to a genus that currently encompasses only European and Asian ground squirrel and made the combination Citellus variegatus douglasi, continuing his earlier incorrect spelling. Joseph Grinnell considered Douglas ground squirrel a subspecies of the California ground squirrel, forming the new combination Citellus beecheyi douglasi in 1913 and copying the incorrect spelling of Richardson's the epithet douglasii. In 1918 Grinnell raised Douglas ground squirrel to be a separate species making the combination Citellus douglasii. L.K. Couch, in an article on its distribution, made an error in this name, creating the combination Citellus douglasi. Gerrit Smith Miller Jr. raised the subgenus Otospermophilus to a separate genus, maintaining the Douglas ground squirrel as a subspecies of the rock squirrel, combining the new name Otospermophilus grammurus douglasii in 1924. In 1931, E.R. Edge was the first to use the current name combination Otospermophilus douglasii.
Douglas ground squirrel is classified in the Rodent order, suborder Sciuromorpha, Squirrel family, Ground squirrel tribe. Several scientific authors considered it one of eight subspecies of the California ground squirrel. Recent comparison of homologous DNA prompts the recognition of California ground squirrel, rock squirrel and Douglas ground squirrel as separate species, as well as including a form from southern Baja California, formerly known as Otospermophilus atricapillus to subspecies of the California ground squirrel. A biogeographic barrier separates the populations of Douglas ground squirrel and the California ground squirrel, the former being restricted to the west and north, and the latter east and south of the Sacramento River. The precise division between these species in southeastern Yolo and Solano counties, and along the northwestern margin of the Sacramento–San Joaquin River Delta, needs further research. Experiments in a laboratory showed these two species can easily hybridize.[1]
Naming
De genus sname is a compilation of the Greek words ὠτός (otos) meaning "ear", σπέρματος (spérmatos) "seed" and φίλος (phílos) "loved". This name was chosen because this group of ground squirrels has relatively large ears. The species was named in honor of Scottish botanist David Douglas, who explored the Pacific coast and was offered the skin of the type specimen.[1]
Behaviour
Douglas ground squirrel digs underground burrows it often shares with other individuals. These burrows have several functions, including food storage, giving birth and nursing the young, providing shelter from bad weather and to escape from predators. During spring and summer, these squirrels spend more time at the surface, eating and collecting food. The young, born early in the year, also become more active over the season. From November through to January, with fewer day light hours, less favourable weather, and less fresh food, the animals spend more time in their burrows. Large groups of these squirrels have several tunnel systems that are used by both males and females members. In these large groups, the number of adult females can be twice as high as the number of males. Adult resident males are probably aggressive to males from the outside and so largely keep territories in the same hands over the seasons. Adult males may often act as sentries, chirping loudly to warn the group of potential predators, illustrating one benefit of living in social groups. Sentries distinguish between birds of prey and harmless avian species. Several types of contact between group members are distinguished. An individual greeting another squirrel and then retreating is called "approach and withdrawal". Mutual grooming, or individuals sniffing and touching noses, cheeks, body, and region under the tail base is called "greeting and social investigation". Playfull chasing, boxing, wrestling and mounting each other, mostly by juveniles, is called "play". When one individual retreats from advances of another squirrel, apparently to avoid aggression, is called displacement. Attaining warning postures, pushing other individuals, sometimes escalating into biting and kicking, to make the opponent retreat is called "aggression". This may include females chasing off other adults, and aggression between males. A male repeatedly tapping a female on forelimb or shoulder is a courtship behavior intended to elicit mating. This is called "push-paw".[1]
Babiana petiolata is a perennial plant species of 8–14 cm (3.1–5.5 in) high assigned to the Iridaceae-family. It is endemic to the Western Cape province of South Africa.
Desciption
Babiana petiolata is a perennial of 8–14 cm (3.1–5.5 in) high including its leaves, that emerges each growing season from an underground corm. The hairless stem is entirely underground, without or with one or two sidebranches, without the collar of fibres around base that is characteristic for the vast majority of other Babiana species, reproducing vegetatively by producing small cormlets from the first node above the corm. The lance- to sword-shaped leaves are shallowly pleated, thinly covered in rough papillae to virtually smooth, often on a cylindrical false petiole of 5–40 mm (0.20–1.57 in) long. The leaves arch forward and are concave with its margins facing toward the ground and that are sometimes thickened. The two hairless bracts that subtend each flower are 15–20 mm (0.59–0.79 in) long. The outer bract is keeled above and sparsely hairy on the keel and margins, with a blunt tip, and pale brown margins. The inner bract has sparsely hairy keels, is slightly shorter than outer, divided all the way to the base, and has broad membranous margins. The four to six violet mirror-symmetrical flowers are set in an inclined spike and have a faint iris-like scent. The lower tepals have pale yellow markings, reddish near the base. The perianth tube is obliquely funnel-shaped, about 11 mm (0.43 in) long, the lower cylinder-shaped part is about 7 mm (0.28 in) long. The tepals are unequal, with the dorsal tepal held slightly apart from the others, about 30 mm × 8 mm (1.18 in × 0.31 in), the upper lateral tepals smaller, the lower three tepals merged to the upper lateral tepals for about 5 mm (0.20 in) and to one another for about 3 mm (0.12 in), the lower median tepal narrowing below to a channelled claw. The stamens are crowded near the dorsal tepal and have curved filaments are about 12 mm (0.47 in) long and topped by about 6 mm long pale violet anthers that release cream-coloured pollen. The hairless egg-shaped ovary is about 4 mm (0.16 in) long. The style arches over the stamens, and divides into three branches of about {cvt|5|mm|in}} long opposite the tips of the anthers and widen at their tips. Flowers mostly occur in July.
Distribution and ecology: Western Cape: between Lambert’s Bay and Velddrif; flat sandy ground in strandveld along the coast (Map 31).
A late winter-flowering species, Babiana petiolata has until recently been overlooked, probably because little collecting was undertaken along the west coast of Western Cape early in the season. When in fruit, plants are inconspicuous, but we have established that the species is relatively common along the narrow band of strandveld that extends from Velddrif northward to Lambert’s Bay.
Description
Babiana rubella is a perennial plant of 10–12 cm (3.9–4.7 in) high, that emerges from a deep-seated corm of up to 3 cm (1.2 in) in diameter. The base of the stem has a well-developed fibrous collar that extends above the ground. The infloresce is a suberect to inclined simple spike or having one branch, that is covered by leaf sheaths and densely long-hairy where it is exposed. The broadly lance-shaped to ovate leaves are held obliquely or almost at a right angles to the leaf sheaths, slightly pleated, densely set with long hairs of up to 4 mm (0.16 in) long on the veins and margins. The variably hairy leaf sheaths are short, broad and overlapping. The 2 bracts that are subtending the flowers are 1½-2½ cm long, densely hairy, green with the tips drying to rusty brown, the inner about as long as the outer, forked only at the tip or as far at midlength, or transparent along the upper mid-line.
Flowers (2)3-6 per spike, bilabiate, pale to deep pinkish purple, lower lateral tepals yellow with pink tips, lightly rose-scented; perianth tube 12-15 mm long, ± half as long as tepals; dorsal tepal 28-30 x ± 8-9 mm, lower tepals joined to upper laterals for ± 5 mm and to one another for ± 3 mm, upper laterals ± 24 mm long, lower tepals 23-25 mm long, crisped along lower margins. Stamens unilateral; filaments arched, ± 14 mm long; anthers ± 4.5 mm long, pale bluish; pollen white. Ovary smooth, ± 3 mm long; style arching over stamens. Capsules and seeds unknown. Flowering time : August to early September. to short, broad imbricate leaf sheaths,