Thomomys bulbivorus is the largest member of the genus, at nearly 325 mm total length and 550 g. Like all members of the genus, T. bulbivorus has small ears and eyes, short legs, powerfully built shoulders, slim hips, fur-lined cheek pouches, and a nearly naked tail. The dorsum is a dark brown, and the ears and nose are tipped blackish. The venter is grey, with exception of a white patch on the throat. Winter pelage is long and soft, whereas summer pelage is short and coarse. Incisors are highly procumbent and protrude, with the lips closing behind them.
Carraway (1987) ; Parker (1990) ; Blair (1957)
Range mass: 550 (high) g.
Average length: 325 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes alike
Thomomys bulbivorus is fossorial, found exclusively in the rich soil of the Willamette Valley in central Oregon. Carraway (1987) ; Blair (1957)
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: savanna or grassland ; forest
Other Habitat Features: agricultural
Thomomys bulbivorus is found only in the Willamette Valley of Oregon (located in the northwestern United States). Blair (1957) ; Carraway (1987)
Biogeographic Regions: nearctic (Native )
The generic name Thomomys arises from the Greek roots, meaning 'a heap' and 'mouse.' The specific name bulbivorus comes from the Latin meaning 'bulb-eater.' Carraway (1987)
Most sounds made by this species are produced by the teeth, usually a 'chatter' or 'grinding' sound. However, when males and females are placed together, a 'crooning' sound can also be heard.
Communication Channels: acoustic ; chemical
Perception Channels: tactile ; acoustic ; chemical
While this species is only found in the Willamette Valley of Oregon, it is relatively common there, and thus has no special conservation status. Carraway (1987)
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
In agricultural areas these animals are considered pests because they eat crops, cut the roots of yound trees, and can cause local flooding by tunneling through dikes. Nowak and Paradiso (1983)
Negative Impacts: crop pest
Pocket gopher are in many ways valuable to humans. By tunneling, they keep the earth porous and friable. Furthermore, they keep the soil rich by burying vegetation. Also, their burrows serve to conserve both water and soil when the snow melts (the resultant runoff enters the gopher burrows). Nowak and Paradiso (1983)
Ecosystem Impact: soil aeration
The diet of T. bulbivorus consists of roots, bulbs, leaves, cultivated crops, and other vegetation. While they may procure plants that grow above ground when they come out at night, they more often burrow under the plants, bite off the roots, and pull the stems down into the burrow. This vegetation is then cut into smaller pieces and pushed into the fur-lined cheek pouches with the front claws, eventually to be carried to a storage or eating place. Nowak and Paradiso (1983)
Plant Foods: leaves; roots and tubers; wood, bark, or stems; flowers
Foraging Behavior: stores or caches food
Primary Diet: herbivore (Folivore )
The breeding season of T. bulbivorus extends from the beginning of April to early June. Studies suggest a range in litter size from four to nine. At birth, young weigh approximately 6g and are about 50mm long. The young lack hair, teeth, and pockets, although growth is rapid. By two weeks young begin to develop hair. At three weeks they crawl and begin to eat solid food, and by four weeks have formed cheek pouches. At five and six weeks respectively, they open their eyes and are weaned. Sexual maturity is attained by the breeding season following birth. Carraway (1987)
Breeding interval: These pocket gophers breed once yearly.
Breeding season: Breeding occurs from April to early June.
Range number of offspring: 4 to 9.
Average weaning age: 6 weeks.
Average time to independence: 6 weeks.
Average age at sexual or reproductive maturity (female): 10 months.
Average age at sexual or reproductive maturity (male): 10 months.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Thomomys bulbivorus és una espècie de rosegador de la família dels geòmids. És endèmic d'Oregon (Estats Units). Es tracta d'una espècie excavadora que s'alimenta principalment de plantes subterrànies El seu hàbitat natural són les comunitats serials primerenques, tot i que també se'l troba a zones cultivades de característiques similars. Es creu que no hi ha cap amenaça significativa per a la supervivència d'aquesta espècie.[1]
Thomomys bulbivorus és una espècie de rosegador de la família dels geòmids. És endèmic d'Oregon (Estats Units). Es tracta d'una espècie excavadora que s'alimenta principalment de plantes subterrànies El seu hàbitat natural són les comunitats serials primerenques, tot i que també se'l troba a zones cultivades de característiques similars. Es creu que no hi ha cap amenaça significativa per a la supervivència d'aquesta espècie.
Die Camas-Taschenratte (Thomomys bulbivorus) ist eine im westlichen Nordamerika lebende Nagetierart aus der Familie der Taschenratten (Geomyidae). Der Artname leitet sich von den lateinischen Worten bulbus und voro mit den Bedeutungen „Zwiebel“ und „fressen“ ab und bezieht sich auf eine Nahrung der Tiere.[1] Der deutsche Trivialname bezieht sich auf die Prärielilien (Camassia), deren Zwiebeln gelegentlich zur Ernährung der Tiere beitragen.
Camas-Taschenratten sind die größten Tiere ihrer Gattung. Ihr Aussehen variiert stark, nicht nur in Bezug auf Alter, Geschlecht und Jahreszeit. Die Rückenfellfarbe kann von einem sehr dunklen Rußbraun bis zu einem hellen Rotbraun reichen. Die Unterseite ist bis auf einen unregelmäßig geformten weißen Fleck am Hals bleifarben. Das Fell variiert je nach Jahreszeit, wobei es im Winter lang und pelzig und im Sommer kurz und grob ist. Sie haben kleine, schwache Augen, kleine Ohren, kurze Beine, kräftig gebaute Schultern, schlanke Hüften sowie einen fast nackten Schwanz, der 40 bis 95 Millimeter lang sein kann. Sie haben pelzige Backentaschen und erreichen eine Gesamtlänge von 228,6 bis 330,2 Millimetern und ein Gewicht von durchschnittlich 633 Gramm.[2] Die Krallen an den Vorderfüßen sind länger als die an den Hinterfüßen. Ihre vorderen Krallen sind die kleinsten in der Gattung und relativ schwach ausgebildet. Stattdessen verwenden sie beim Graben in der Erde ihre großen meißelartigen Schneidezähne. Sowohl der obere als auch der untere Schneidezahn haben aufgrund des Abriebs des gelben Oberflächenschmelzes eine weiße Spitze und sind ziemlich schmal. Die Schneidezähne ragen hervor, wobei sich die Lippen hinter ihnen schließen. Eine Rille am Mittelrand jedes Schneidezahns fehlt, die hingegen bei anderen Mitgliedern der Gattung vorhanden ist. Die Zahnformel lautet I1/1-C0/0-P1/1-M3/3 mit insgesamt 20 Zähnen.[1]
Ähnliche Tiere aus der Gattung der Gebirgs-Taschenratten (Thomomys) sind sämtlich kleiner und unterscheiden sich durch kräftigere Krallen sowie eine Rille in den Schneidezähnen.
Die Camas-Taschenratte lebt endemisch im Willamette Valley im Nordwesten von Oregon. Die Verbreitung erstreckt sich im Wesentlichen von Portland bis Eugene. Die Art bewohnt Lebensräume mit reichem, fruchtbarem Boden und meidet Nadelholzbestände. Ihre Lebensräume liegen in der Regel zwischen 120 und 125 Metern über dem Meeresspiegel. Sie verschmäht Feuchtgebiete, hingegen besiedelt sie landwirtschaftlich genutzte Flächen. Obwohl die Art nur in einem verhältnismäßig begrenzten Gebiet vorkommt, wird sie von der Weltnaturschutzorganisation IUCN als „Least Concern = nicht gefährdet“ klassifiziert.[3] In Oregon wird sie jedoch als „species of concern (Art mit Bedenken)“ geführt.[4]
Camas-Taschenratten halten sich überwiegend unter der Erdoberfläche auf und leben außerhalb der Paarungszeit einzeln. Die Tiere sind tag- und nachtaktiv und halten keinen Winterschlaf. Sie legen sehr aufwendige, tunnelartige Gangsysteme mit verschiedenen Kammern an. Auf niedrigen Graslandschaften befinden sich die Gänge oft weniger als 0,30 Meter unter der Oberfläche, während sie in anderen Erdformationen auch in maximalen Tiefen von 1,5 bis 1,8 Metern unter der Erdoberfläche gefunden wurden. Die Tunnel werden in erster Linie mit den großen Schneidezähnen gegraben, das lockere Aushubmaterial wird mit dem Kopf oder den Beinen in Form von Erdhügeln an die Oberfläche befördert.
Tunnel- und Kammeranordnung eines ausgegrabenen Baues
Die umfangreichen Tunnelsysteme erreichen oftmals eine Gesamtlänge von 180 Metern, überschreiten jedoch selten 240 Meter.[1] Je nach Alter und Größe der Individuen reichen die Durchmesser der Tunnel von 51 bis zu 127 Millimetern.
Die Camas-Taschenratte ernährt sich von einem breiten Spektrum unter- und oberirdischer Pflanzenteile wie Wurzeln, Knollen, Zwiebeln, Blättern und Früchten. Sie wurden auch beim Verzehr von Zwiebeln von Prärielilien (Camassia) beobachtet, die im Willamette Valley wachsen. Gerne ernähren sie sich auch von den Wurzeln und der Rinde von Kernobst- und Nussbäumen, die dadurch zuweilen stark geschädigt werden. Sie werden deshalb in Oregon als Schädling geführt.[5] Mit ihren Backentaschen transportieren sie vielfältige Nahrung zu ihren unterirdischen Bauen und legen in Kammern große Nahrungsdepots an.
Die Brutzeit der Camas-Taschenratten dauert von Anfang März bis Anfang Juli. Nach der Paarung verlassen die Weibchen ihre Höhlen, um einen sicheren Ort zu finden, an dem sie sich und ihre Jungen vor der Geburt vor möglichen Bedrohungen schützen können. Die Tragzeit beträgt 18 bis 19 Tage. Ein Wurf besteht in der Regel aus vier bis neun Jungen, im Durchschnitt 4,2. Nach sechs Wochen sind sie nahezu ausgewachsen und es beginnt die Entwöhnungsphase. Nachdem sie aus dem Bau des Muttertiers verjagt wurden, suchen sie nach eigenen Höhlen und leben dann einzeln. Sie erreichen ein Jahr nach der Geburt die Geschlechtsreife.[1]
Zu der großen Anzahl an Fressfeinden zählt in erster Linie der Silberdachs (Taxidea taxus).[2] Dieser gräbt die Opfer zuweilen mit seinen langen, gebogenen Krallen aus den unterirdischen Erdhöhlen aus. Auch Kojoten (Canis latrans), Wiesel und Schlangen versuchen die Tiere zu erbeuten. Bei Begegnungen mit diesen Raubtieren und anderen Bedrohungen, reagieren sie im Allgemeinen mit offenem Maul, nehmen eine bedrohliche Haltung an, erzeugen keuchende Geräusche und heben die Vorderseite ihres Körpers leicht an, wobei ihre Zähne und Krallen nach vorne gestreckt werden. Sofern diese Drohgebärden keine Wirkung hinterlassen, versuchen sie durch Flucht ihren Feinden zu entkommen. Zu weiteren Fressfeinden zählen auch verschiedene Eulenarten (Strigiformes).
Die Camas-Taschenratte (Thomomys bulbivorus) ist eine im westlichen Nordamerika lebende Nagetierart aus der Familie der Taschenratten (Geomyidae). Der Artname leitet sich von den lateinischen Worten bulbus und voro mit den Bedeutungen „Zwiebel“ und „fressen“ ab und bezieht sich auf eine Nahrung der Tiere. Der deutsche Trivialname bezieht sich auf die Prärielilien (Camassia), deren Zwiebeln gelegentlich zur Ernährung der Tiere beitragen.
The camas pocket gopher (Thomomys bulbivorus), also known as the camas rat or Willamette Valley gopher, is a rodent, the largest member in the genus Thomomys, of the family Geomyidae. First described in 1829, it is endemic to the Willamette Valley of northwestern Oregon in the United States. The herbivorous gopher forages for vegetable and plant matter, which it collects in large, fur-lined, external cheek pouches. Surplus food is hoarded in an extensive system of tunnels. The dull-brown-to-lead-gray coat changes color and texture over the year. The mammal's characteristically large, protuberant incisors are well adapted for use in tunnel construction, particularly in the hard clay soils of the Willamette Valley. The gophers make chattering sounds with their teeth; males and females make purring (or crooning) sounds when they are together, and the young make twittering sounds. Born toothless, blind and hairless, the young grow rapidly before being weaned at about six weeks of age.
Although the camas pocket gopher is fiercely defensive when cornered, it may become tame in captivity. While population trends are generally stable, threats to the species' survival include urbanization, habitat conversion for agricultural use and active attempts at eradication with trapping and poisons. It is prey for raptors and carnivorous mammals, and host to several parasitic arthropods and worms. Scientists believe that the gopher's evolutionary history was disrupted when the Missoula Floods washed over the Willamette Valley at the end of the last ice age. The floods almost completely inundated its geographic range, which may have caused a genetic bottleneck as survivors repopulated the region after the waters receded.
There are six genera of North American pocket gophers: Cratogeomys, Geomys, Orthogeomys, Pappogeomys, Thomomys, and Zygogeomys.[3] The camas pocket gopher is a smooth-toothed pocket gopher of the genus Thomomys, within the pocket-gopher family Geomyidae.[4] The incisors of gophers in the genus Thomomys have characteristically smooth anterior surfaces, while those of Geomys have two deep grooves per tooth and those of Cratogeomys have a single groove.[5] The camas pocket gopher is a member of the subgenus Megascapheus, established in 1903, at that time for the camas pocket gopher alone.[4][6] Taxonomists subsequently assigned other gophers to the same subgenus.[7] The name Thomomys derives from the Greek σωρός (heap) + μῦς (mouse), probably describing the mounds of excavated soil produced by the burrowing gopher.[8] Bulbus translates as "bulb" in Latin, and the word for "devour" is voro.[8] Naturalist David Douglas reported that the gopher consumed bulbs of the camas lily,[9] and Vernon Bailey later attributed the lack of camas lilies in areas inhabited by the gopher to the bulbs being eaten.[10] However, naturalist H. M. Wight observed that the gopher ate primarily dandelion greens, and was skeptical that it was a large consumer of bulbs.[10][11]
The taxonomy of the camas pocket gopher and its genus, Thomomys, have a convoluted history.[12] According to a review article published by the American Society of Mammalogists in 1987, Johann Friedrich von Brandt was the first to refer to the camas pocket gopher as Thomomys bulbivorus in an 1855 article published by the Imperial Academy of Sciences.[6] In the 1855 article, Brandt refers to Tomomys bulbivora without the "h" and ending with an "a".[13] He writes parenthetically "(man schreibe nicht Thomomys)".[14] The authors of the 1987 review note that they did not see Brandt's actual article, but source the textbook The mammals of North America published in 1981.[6]
Early confusion arose from writings by John Richardson between 1828 and 1839.[15] Although he describes six species in the genus, according to later critics he was unfamiliar with all specimens.[12] Richardson's descriptions of the animals and the figures in the text were also criticized.[12] His 1829 Fauna boreali-americana describes a type specimen of camas pocket gopher obtained from the "banks of the Columbia River, Oregon", the northern limit of the gopher's geographic range.[9][16] This was probably Portland, at the confluence of the Willamette and Columbia Rivers, the only place on the Columbia where subsequent specimens have been found.[2] The present location of this initial specimen is uncertain;[2] reportedly stored at the Hudson Bay Museum, it could not be located in 1915.[2] When Richardson made his first examination, the specimen was apparently incomplete;[12] although Joel Asaph Allen wrote in 1893 that it consisted only of the skin,[17] Richardson described the skull and facial features in detail.[18]
In Fauna boreali-americana, Richardson assigns the mammal to the now-defunct genus Diplostoma described by Rafinesque in 1817.[9] He named it Diplostoma ? bulbivorum.[12] Illustration-labeling errors in Richardson's book further confounded subsequent taxonomists; the plate was labeled Diplostoma douglasii.[12]
There is a specimen of a quadruped in the Hudson's Bay Museum, which Mr David Douglas informs me is the animal known on the banks of the Columbia by the name of the camas-rat, because the bulbous root of the Quamash or Camas plant (Scilla esculenta) forms its favourite food. The scull is wanting, and the animal, therefore, cannot be with certainty referred to a genus, but the form of its exterior cheek-pouches leads me to think that it may belong to the diplostoma of M Rafinesque-Schmaltz.
— John Richardson, Fauna boreali-americana, 1829[9]
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The confusion around the species' taxonomy and identification amplified when naturalist Spencer Fullerton Baird interpreted Richardson's reports.[17] The camas pocket gopher's large size led Baird to conclude that the animal's measurements (reported by Richardson) were an artifact of its taxidermy preparation.[19] Baird was also apparently in error about the location from which the specimen was taken,[17] attributing the name Thomomys bulbivorus to a set of previously collected specimens later known as the California Gopher.[17] This confusion was echoed by subsequent authors.[17] The article on gophers in the 1879 edition of the American Cyclopædia has an illustration captioned "California Gopher (Thomomys bulbivorus)".[20] The ninth edition of the Encyclopædia Britannica (published during the late 19th century) mistakenly reports Thomomys bulbivorus as abundant along the central California coast.[21]
Although Baird and Elliott Coues were involved in early assessments of the genus, according to Allen neither ever saw a specimen of the camas pocket gopher (T. bulbivorus).[17] Allen obtained and examined two large adults (male and female) collected in Beaverton, Oregon, in May 1890[17] which were considerably larger and darker than previously examined specimens.[22] Skull features and white markings around the mouth and anus also differed.[22] His findings and the specimen-collection location helped identify the camas pocket gopher as a species separate from California gophers.[22] The California specimens were classified by Eydoux and Gervais as Oryctomys bottae, now known as Thomomys bottae (Botta's pocket gopher).[22] They were found near Monterey, California, over 1,000 kilometers (620 mi) south of the now-recognized range of the Camas pocket gopher.[22]
The distribution of Elliot's "great pocket gopher" (as it was known) extended along the California coast "north of San Francisco."[23] James Audubon and John Bachman reassessed the taxonomy on the camas pocket gopher in the late 1800s. They referred it as the "camas rat". They reclassified the gopher as Pseudostoma borealis.[24] They rejected Diplostoma as a genus, and assigned Diplostoma bulbivorum as synonymous with P. borealis. They attributed any differences described by Richardson to artifact, from a specimen that was "twisted and disfigured" in preparation.[25] Based on observations of taxidermy specimens in Europe, they suggested that Townsend's pocket gopher (Geomys (Thomomys) townsendii) belonged to the same species.[26] In 1875, the camas pocket gopher was reported as a sub-species of the northern pocket gopher (Thomomys talpoides),.[27] During the 1920s H. M. Wight referred to it colloquially as the "Willamette Valley gopher".[28]
In 2008, a team of biologists from the University of California, Berkeley and Harvard University published multilocus phylogenetic analysis results of the genus Thomomys. The camas pocket gopher was found to be well separated from other taxa in the subgenus Megascapheus. These findings suggested that the camas pocket gopher was a sister to the other taxa in the subgenus, but the relationships between those other animals was less clear.[29] Only one camas pocket gopher was included in this study, which limited the ability to distinguish features such as monophyly.[30] The following cladogram was presented showing the placement of the camas pocket gopher among its closest relatives:[30]
Thomomys ThomomysMazama pocket gopher (Thomomys mazama)
Idaho pocket gopher (Thomomys idahoensis)
Mountain pocket gopher (Thomomys monticola)
Northern pocket gopher (Thomomys talpoides)
MegascapheusCamas pocket gopher (Thomomys bulbivorus)
Southern pocket gopher (Thomomys umbrinus)
Townsend's pocket gopher (Thomomys townsendii)
Botta's pocket gopher (Thomomys bottae)
Patterns of genetic variation in the camas pocket gopher have been studied.[31] Although there are no subspecies, there is substantial genetic diversity within the species. Its genetic patterns are consistent with limited inbreeding within specific populations.[32] This is similar to patterns described in Botta's pocket gopher and the southern pocket gopher, both of which are members of the same genus. However, it contrasts with patterns noted in Baird's pocket gopher and the plains pocket gopher, members of a separate genus, Geomys, which showed a higher degree of inbreeding.[32]
The species' genetic diversity is similar to that of other pocket gophers occupying a larger geographic range and diversity of habitat.[33] Compared to Townsend's pocket gopher, which is distributed across a much larger area, but less diverse habitat, it is more genetically heterogeneous.[33] Although there is considerable differentiation between separate populations of camas pocket gophers, their genetic variability does not affect the mammal's appearance.[34] Study of the effects of genetic change over time revealed a pattern affected by a cataclysmic event across the species' entire geographic area about 13,000 years ago.[34] Such an event would cause a population bottleneck, leading to scattered, isolated populations.[34]
The camas pocket gopher is, by a small margin, the largest member of its genus (Thomomys).[35] The fur is a dull brown above and dark, leaden gray beneath.[36] There are often patches of white on the chin, throat and around the anus,[37] and it has blackish ear and nose markings.[6] The external ear is a thickened rim of tissue.[37] During the summer, the gopher's coat is short and coarse; winter pelage is longer and furrier.[6] The coat of the young is similar to the adult summer coat, but with more sparsely distributed fur; the abdominal skin may be visible.[37]
Like other gophers, it has small eyes and ears and a nearly hairless tail. Its shoulders are broader than its hips. It is pentadactyl, with five claws on each foot. The claws on its forefeet are longer than those on its hind feet, and its middle claws are longest.[6] The front claws of the camas pocket gopher are short and weak relative to its size.[38] It employs plantigrade locomotion. The male is larger than the female, measuring an average 300 mm (12 in) in length. A large male weighs about 500 g (18 oz).[6] One male specimen was 321 mm (12.6 in) long and weighed 633.8 g (22.36 oz).[35] Females are about 271 mm (10.7 in) long. The tail measures 90 mm (3.5 in) in the male and 81 mm (3.2 in) in the female. An adult male's hind feet measure 40–43 mm (1.6–1.7 in), and an average female's hind feet measure 39 mm (1.5 in).[6] There are four mammary glands: two in the inguinal region and two in the pectoral region, each supplying a pair of nipples.[2] Morphologically, it most closely resembles Botta's pocket gopher;[37] differentiation can be made based on the concavity of the inner surface of the pterygoids, small claws, more uniform fur coloring and exoccipital groove of the camas pocket gopher.[39][40]
The skull of the camas pocket gopher is sturdily proportioned.[39] The camas pocket gopher and other smooth-toothed pocket gophers with robust snouts are included in the subgenus Megascapheus.[35] Male skulls measure 52 mm (2.0 in) in length across the base and 57 mm (2.2 in) if the incisors are included. The short, wide skull has a relatively short nasal passage. In width, the skull measures 19 mm (0.75 in) across the nasal passages, 30.5 mm (1.20 in) across the mastoids and 36.5 mm (1.44 in) at the zygomatic arches.[6] The external auditory meatus is broad and open, although the auditory bullae are confined.[37]
The dentition of the camas pocket gopher is symmetric, with one set of incisors, one set of premolars, and three sets of molars above and below. This gives a dental formula of 1.0.1.31.0.1.3, for a total of 20 teeth.[6] The slender incisors are prominent and distinctive, smooth with yellow surface enamel and white tips due to soil abrasion.[37] These distinctive, large, protuberant upper incisors give the gopher a buck-toothed appearance.[6][36] The lips do not cover the incisors, but close behind them. There are faintly visible grooves on the inner aspect of the upper incisors, which are more pronounced in other members of the genus (such as the Mazama pocket gopher, T. mazama). The upper molars have an alveolar length of 10 mm (0.39 in).[6]
Gophers are burrowing rodents of the family Geomyidae, characterized by fur-lined, external cheek pouches used to gather and transport food.[41] The cheek pouches of geomyids such as the camas pocket gopher are controlled by a set of muscles,[42] with a sphincter controlling the opening and closing of the pouch. A pair of muscles attached to the premaxilla pull the pouches forward, and paired retractor muscles pull the pouches back.[42] These retractor muscles extend back and up from the cheek surfaces, forming a band 7–10 cm (2.8–3.9 in) long and about 2 cm (0.79 in) wide[6] attached to aponeurosis of the latissimus dorsi muscle.[42]
Like many mammals, the penis of the camas pocket gopher contains a bone, the baculum. Although its baculum was initially reported as smaller than that of other gophers—1.5 mm (0.059 in) high, 1.8 mm (0.071 in) wide at the base and 8.5 mm (0.33 in) long—the examiner did not know if the specimen had reached full maturity.[43] Subsequent reports averaged about 2.1 mm (0.083 in) high, 2.2 mm (0.087 in) wide at the base and 10.1 mm (0.40 in) long.[44] The phallus' total length averaged 13.5 mm (0.53 in), with the glans covering more than half its length.[6]
The camas pocket gopher is found in the Willamette Valley and the drainage areas of the Yamhill River and other tributaries of the Willamette River.[6] Its range extends north from Eugene to Portland and Forest Grove and west to Grand Ronde.[2] A 1920 report of a Pleistocene fossil in Fort Rock, Oregon has been questioned, since it is far outside the species' current geographic range; as of 1987, the specimen could not be located for further evaluation.[6]
The clay-rich Willamette Valley soils are hard in the dry season, and the gopher's protuberant incisors are well adapted to these conditions.[37] Adequate soil drainage and suitable plant food are essential components of the gopher's ideal habitat. Not typically found in wetland areas (where its tunnels would flood), the species is found in seral communities of grasses and shrubs. They are also established in agricultural fields in the Willamette Valley, including fields of alfalfa, wheat and oats. The species has also been found in areas of ecological disturbance with similar terrain features.[45]
On a geologic timescale, the Willamette Valley has been the site of massive floods.[46] During the late Wisconsin glaciation, a series of floods (known as the Missoula or Bretz Floods) occurred.[46] The last flood in the series, a massive flood with an estimated 1,693 km3 (406 cu mi) of water flowing at a rate of 42 km3 per hour (412 million ft3 per second) over a 40-hour period,[46] occurred about 13,000 years ago. The flood filled the Willamette Valley to a depth of about 122 m (400 ft), in a near-perfect overlay of the camas pocket gopher's range.[32] Although the species has been collected above this elevation, such finds are uncommon.[45] A temporary lake, Lake Allison, formed.[32] Although it is assumed that the gopher lived in the valley before the flood, no fossils have been recovered. The Chehalem Mountains, with a peak elevation of 497 m (1,631 ft), probably provided refuge for survivor populations and survivors would have repopulated in isolated pockets when the waters receded. Before and since the floods, the mountains are thought to have limited gene flow between populations. The relatively narrow, sluggish Willamette River does not appear to obstruct genetic flow in gopher populations.[34]
The gopher has been credited with being one of the most vicious animals known for its size. It has a great deal of courage and fights a man savagely until an opportunity for escape is offered, then it turns and runs as rapidly as possible, attempting to hide from its pursuer.
— H. M. Wight, Economic Entomology: Pamphlets, 1918[47]
The camas pocket gopher is a mostly solitary herbivore which is active throughout the year and does not hibernate.[48] The gopher spends most of its time excavating tunnels in search of food,[49] and the hard clay soils of the Willamette Valley pose a challenge.[10] Although the gopher's front claws are too weak to dig through the clay (particularly during dry seasons), its large incisors and strongly protuberant orientation are well-adapted for this purpose. Tunnel systems constructed by the camas pocket gopher can be complex, with some tunnels exceeding 240 m (260 yd) in length. About 90 mm (3.5 in) in diameter, the tunnels are up to 0.91 m (3.0 ft) deep.[10] When soils are damp the gopher constructs ventilation ducts or chimney mounds (possibly unique to the species),[49] to increase ventilation.[10] The chimney mounds rise vertically 15–25 cm (6–10 in), are open at the top and are thought to ventilate the burrows in accordance with Bernoulli's principle.[49] It is not known if adjacent gopher burrowing systems interconnect.[49] Reports differ about whether or not the ranges of the camas pocket gopher and the Mazama pocket gopher overlap; if so, this refutes the previous belief that Oregon gopher ranges do not overlap.[10]
Although the species is primarily fossorial, it occasionally gathers food near the entrance of a tunnel.[10] Dandelions seem to be its favorite food, and are also used as nesting material.[50] During breeding season males will enter the tunnels of females, and males and females may make purring (or cooing) sounds when they are together.[51] Mothers seem to comfort the young by softly vocalizing,[51] with the young twittering in response.[28]
The camas pocket gopher may behave aggressively when on the defensive, with mammalogist Vernon Orlando Bailey describing the species as "morose and savage."[10] However, it may be easily tamed in captivity;[49] the female is more readily tamed than the male.[52] Another small rodent endemic to the Willamette Valley, the gray-tailed vole (Microtus canicaudus), also uses camas pocket gopher tunnels. Other mammals sharing the range of the camas pocket gopher (and, possibly, its tunnels) include the vagrant shrew, Townsend's mole, the brush rabbit, the eastern cottontail rabbit, Townsend's chipmunk, the California ground squirrel, the dusky-footed woodrat, the North American deermouse, the creeping vole, Townsend's vole, the Pacific jumping mouse, the long-tailed weasel and the striped skunk.[10]
Varying onset times and duration of the camas pocket gopher breeding season have been reported. Early reports suggested an early-April onset, with the season extending through June. Other reports cited "evidently pregnant" females seen in late March.[44] In heavily irrigated areas the breeding season may be longer, extending into early September.[45] About four young are born in a litter, although litters as large as nine have been reported.[44] The blind, hairless, toothless offspring weigh about 6.1 g (0.22 oz) and are 50 mm (2.0 in) in length.[44] During their first six weeks they will begin to crawl, develop cheek pouches, open their eyes and wean from milk to solid food.[44] The young then weigh about 86 g (3.0 oz) and measure 164 mm (6.5 in) in length.[44] At weeks 8, 10 and 17 they will weigh 101 g (3.6 oz), 160 g (5.6 oz) and 167 g (5.9 oz).[44] Some reports indicate that more than one litter may be born in a season.[45] Sexual maturity probably develops by the following year's breeding season.[44] Although males are fully grown by that time, females may continue to increase in size.[45]
There was little data as of 1998 on the longevity and mortality of the camas pocket gopher.[45] It is presumably prey for carnivorous mammals, and its bones have been identified in regurgitated pellets of raptors such as the great horned owl. Parasites include mites, lice, fleas, roundworms and flatworms. The species' tougher skin may protect it from some fleas known to infest Botta's pocket gopher and the Mazama pocket gopher.[10] Mites known to parasitize the camas pocket gopher include Androlaelaps geomys and Echinonyssus femuralis.[53] Some authorities report Androlaelaps fahrenholzi as another parasitic mite,[10] but a later publication did not report it.[54] The chewing louse Geomydoecus oregonus has also been reported.[10]
Two parasitic worms first discovered in the gastrointestinal tract of camas pocket gophers are the nematode Heligmosomoides thomomyos and the cestode Hymenolepis tualatinensis. Other worms include two nematodes and the cestode Hymenolepis horrida.[10]
Camas pocket gophers cause significant economic losses, so may be treated as an agricultural pest. Crops damaged include clover, alfalfa and vetch.[50] The gophers may eat these crops or damage the roots while burrowing. This can injure the roots and expose them to air, causing them to dry out. Subterranean activity can also damage the roots of fruit trees. Root crops are particularly susceptible to damage and consumption; potatoes, carrots, parsnips and other crops may be eaten on site or dragged off by the gopher for caching in the burrow. Excavated soil can cover grass and limit livestock grazing; freshly sprouted grains may be similarly damaged.[50] An estimate of impact from camas pocket gopher activities in the Willamette Valley in 1918 amounted to $1.5 million annual losses.[50] Gopher activities can provide a benefit of soil aeration, enhancing water retention after rain or snowmelt. Buried vegetation can also compost, enhancing organic soil content to provide additional benefits.[55]
Proposed methods for controlling gopher populations in agricultural areas include poisoning dandelions,[50] clover, carrots, sweet potatoes and parsnips.[10] Camas pocket gophers are larger than other gophers, so conventional gopher traps may fail to capture them.[10] Toxic baits and fumigants may also fail, since the gophers will sometimes wall off a segment of the burrow.[10] Gophers may also cause local flooding if their tunneling activities damage levees.[55]
In an effort to mitigate damage by camas pocket gophers to sensitive habitat, the Oregon Department of Transportation and the Institute for Applied Ecology trap and relocate the animals.[56] At a site south of Philomath, Oregon, the IAE is working to protect a small but viable population of Kincaid's lupine (Lupinus sulphureus).[56] This threatened flower is the primary host plant for the endangered Fender's blue butterfly (Icaricia icarioides fenderi), which is endemic to the Willamette Valley.[57][58] The gophers are relocated to a nearby location distant from the lupines.[56]
Citing concerns of urbanization, habitat loss and active attempts at eradication, NatureServe assessed in 2014 the camas pocket gophers' conservation status as vulnerable.[48] The conservation status of the camas pocket gopher is classified as "least concern" by the IUCN (International Union for Conservation of Nature) Species Programme, with a stable population trend.[1] The IUCN notes that the gopher is common in its range; studies indicate that populations can recover rapidly after traps are removed from an area,[1][45] and the species may adapt well to environmental changes.[1]
The IUCN and others express concern about degradation of the species' habitat due to urbanization and agricultural expansion.[1][59] The total area occupied by the camas pocket gopher is less than 20,000 km2 (7,700 sq mi).[1] This area, the Willamette Valley, contains 70 percent of Oregon's human population.[60] Although this range probably contains a few protected areas, many preserves in the valley are primarily waterfowl protection for hunters.[59] Wetland areas are not suited to the camas pocket gopher, since tunnels are flood-prone. In areas better suited to the gopher (disturbed habitats and pastoral farmland),[45] it may be considered a pest and subject to eradication by poisoning and trapping.[1]
The camas pocket gopher (Thomomys bulbivorus), also known as the camas rat or Willamette Valley gopher, is a rodent, the largest member in the genus Thomomys, of the family Geomyidae. First described in 1829, it is endemic to the Willamette Valley of northwestern Oregon in the United States. The herbivorous gopher forages for vegetable and plant matter, which it collects in large, fur-lined, external cheek pouches. Surplus food is hoarded in an extensive system of tunnels. The dull-brown-to-lead-gray coat changes color and texture over the year. The mammal's characteristically large, protuberant incisors are well adapted for use in tunnel construction, particularly in the hard clay soils of the Willamette Valley. The gophers make chattering sounds with their teeth; males and females make purring (or crooning) sounds when they are together, and the young make twittering sounds. Born toothless, blind and hairless, the young grow rapidly before being weaned at about six weeks of age.
Although the camas pocket gopher is fiercely defensive when cornered, it may become tame in captivity. While population trends are generally stable, threats to the species' survival include urbanization, habitat conversion for agricultural use and active attempts at eradication with trapping and poisons. It is prey for raptors and carnivorous mammals, and host to several parasitic arthropods and worms. Scientists believe that the gopher's evolutionary history was disrupted when the Missoula Floods washed over the Willamette Valley at the end of the last ice age. The floods almost completely inundated its geographic range, which may have caused a genetic bottleneck as survivors repopulated the region after the waters receded.
Thomomys bulbivorus Thomomys generoko animalia da. Karraskarien barruko Geomyidae familian sailkatuta dago.
Thomomys bulbivorus Thomomys generoko animalia da. Karraskarien barruko Geomyidae familian sailkatuta dago.
Le Gaufre bulbivore[1] (Thomomys bulbivorus) est une espèce de rongeurs de la famille des Geomyidae. Elle est endémique de l'Oregon aux États-Unis. Le Gaufre bulbivore est le plus grand des gaufres, atteignant 30 cm.
Cette espèce a été décrite pour la première fois en 1829 par John Richardson (1787-1865), un naturaliste, explorateur et médecin écossais.
Le Gaufre bulbivore (Thomomys bulbivorus) est une espèce de rongeurs de la famille des Geomyidae. Elle est endémique de l'Oregon aux États-Unis. Le Gaufre bulbivore est le plus grand des gaufres, atteignant 30 cm.
Cette espèce a été décrite pour la première fois en 1829 par John Richardson (1787-1865), un naturaliste, explorateur et médecin écossais.
Thomomys bulbivorus is een zoogdier uit de familie van de goffers (Geomyidae). De wetenschappelijke naam van de soort werd voor het eerst geldig gepubliceerd door Richardson in 1829.
Bronnen, noten en/of referenties
Thomomys bulbivorus[2][3][4][5][6][7] är en däggdjursart som först beskrevs av Richardson 1829. Thomomys bulbivorus ingår i släktet Thomomys och familjen kindpåsråttor.[8][9] IUCN kategoriserar arten globalt som livskraftig.[1] Inga underarter finns listade i Catalogue of Life.[8] Artepitet i det vetenskapliga namnet är sammansatt av de latinska orden bulbus (lök) och voro (ätande). Gnagaren är i motsats till denna tidiga teori inte specialiserad på lökar.[10]
Hannar blir omkring 300 mm lång, inklusive en cirka 90 mm lång svans. De har ungefär 42 mm långa bakfötter. Honornas genomsnittsvärden är 271 mm för den absoluta längden, 81 mm för svanslängden och 39 mm för bakfötternas längd. Särskilt stora hannar kan med svans vara 328 mm långa och 495 g tunga. Kroppen är under sommaren täckt av en kort och styv päls som byts före vintern mot en lång och fluffig päls. Den är på ovansidan mörk gråbrun och på undersidan blyfärgad. Det finns en vit fläck på strupen och öronen samt nosen är nästan helt svarta. Thomomys bulbivorus har liksom alla familjemedlemmar kindpåsar och framtänderna ligger utanför den stängda munnen. Honor har två par spenar på bröstet och två par spenar vid ljumsken. I varje käkhalva förekommer en framtand, ingen hörntand, en premolar och tre molarer, alltså 20 tänder i hela uppsättningen.[10]
Denna gnagare förekommer i nordvästra Oregon (USA) i dalgången till Willamette River och dess bifloder. Habitatet utgörs främst av jordbruksmark.[1]
Arten skapar liksom andra kindpåsråttor underjordiska tunnelsystem men den vistas ibland ovanpå markytan. Den äter rötter, rotfrukter och andra underjordiska växtdelar samt gräs, nedfallna frukter och nötter. Före den kalla årstiden samlas föda i boets förvaringsrum. Individerna håller ingen vinterdvala och lever utanför parningstiden ensam. Parningen sker tidigast i mars och ungarna föds mellan april och juli. En hona har bara en kull under tiden med 3 till 5 ungar. Dräktigheten varar cirka 19 dagar och ungarna diar sin mor ungefär 6 veckor. Efter den första vintern har de parningsförmåga.[1] Vid födelsen är ungarna cirka 50 mm långa, 6 g tunga, blinda och nakna. Deras storlek ökas snabb. Ungarna får efter två veckor päls, de börjar efter tre veckor med fast föda och de öppnar ögonen efter fem veckor.[10]
I äldre avhandlingar nämns att denna art fördrar lök från stjärnhyacinter (Camassia) som föda men denna uppgift är omstridd. Thomomys bulbivorus faller ofta offer för ugglor och den jagas troligen av andra rovlevande djur.[10]
Wikimedia Commons har media som rör Thomomys bulbivorus.
Wikispecies har information om Thomomys bulbivorus.
Thomomys bulbivorus är en däggdjursart som först beskrevs av Richardson 1829. Thomomys bulbivorus ingår i släktet Thomomys och familjen kindpåsråttor. IUCN kategoriserar arten globalt som livskraftig. Inga underarter finns listade i Catalogue of Life. Artepitet i det vetenskapliga namnet är sammansatt av de latinska orden bulbus (lök) och voro (ätande). Gnagaren är i motsats till denna tidiga teori inte specialiserad på lökar.
Hannar blir omkring 300 mm lång, inklusive en cirka 90 mm lång svans. De har ungefär 42 mm långa bakfötter. Honornas genomsnittsvärden är 271 mm för den absoluta längden, 81 mm för svanslängden och 39 mm för bakfötternas längd. Särskilt stora hannar kan med svans vara 328 mm långa och 495 g tunga. Kroppen är under sommaren täckt av en kort och styv päls som byts före vintern mot en lång och fluffig päls. Den är på ovansidan mörk gråbrun och på undersidan blyfärgad. Det finns en vit fläck på strupen och öronen samt nosen är nästan helt svarta. Thomomys bulbivorus har liksom alla familjemedlemmar kindpåsar och framtänderna ligger utanför den stängda munnen. Honor har två par spenar på bröstet och två par spenar vid ljumsken. I varje käkhalva förekommer en framtand, ingen hörntand, en premolar och tre molarer, alltså 20 tänder i hela uppsättningen.
Denna gnagare förekommer i nordvästra Oregon (USA) i dalgången till Willamette River och dess bifloder. Habitatet utgörs främst av jordbruksmark.
Arten skapar liksom andra kindpåsråttor underjordiska tunnelsystem men den vistas ibland ovanpå markytan. Den äter rötter, rotfrukter och andra underjordiska växtdelar samt gräs, nedfallna frukter och nötter. Före den kalla årstiden samlas föda i boets förvaringsrum. Individerna håller ingen vinterdvala och lever utanför parningstiden ensam. Parningen sker tidigast i mars och ungarna föds mellan april och juli. En hona har bara en kull under tiden med 3 till 5 ungar. Dräktigheten varar cirka 19 dagar och ungarna diar sin mor ungefär 6 veckor. Efter den första vintern har de parningsförmåga. Vid födelsen är ungarna cirka 50 mm långa, 6 g tunga, blinda och nakna. Deras storlek ökas snabb. Ungarna får efter två veckor päls, de börjar efter tre veckor med fast föda och de öppnar ögonen efter fem veckor.
I äldre avhandlingar nämns att denna art fördrar lök från stjärnhyacinter (Camassia) som föda men denna uppgift är omstridd. Thomomys bulbivorus faller ofta offer för ugglor och den jagas troligen av andra rovlevande djur.
Thomomys bulbivorus là một loài động vật có vú trong họ Chuột nang, bộ Gặm nhấm. Loài này được Richardson mô tả năm 1829.[2] Được mô tả lần đầu tiên vào năm 1829, nó là loài đặc hữu của thung lũng Willamette ở tây bắc Oregon ở Hoa Kỳ. Loài ăn cỏ gopher ăn cỏ cho rau và thực vật, nó thu thập trong túi má ngoài lớn, bên ngoài là lớp lông, bên ngoài má túi. Thức ăn dư thừa được lưu giữ trong một hệ thống đường hầm ngầm rộng lớn. Màng màu xám đậm đến xám xỉn thay đổi màu sắc và kết cấu trong suốt năm. Các răng cửa rộng và đặc trưng của động vật có vú này đặc biệt thích hợp cho việc sử dụng trong xây dựng đường hầm, đặc biệt là ở đất sét cứng của Thung lũng Willamette. Những con vượn cáo làm cho tiếng nói nghẹn lại với răng; Con đực và con cái tạo âm thanh lẩm bẩm (gợi tình) khi chúng ở bên nhau. Con non sinh ra không có răng, mù và không có lông, con non trưởng thành nhanh chóng trước khi cai sữa vào khoảng sáu tuần tuổi. Mặc dù loài này phòng thủ dữ dội khi bị dồn vào, nó có thể trở nên thuần hóa trong tình trạng bị bắt. Mặc dù xu thế dân số nói chung ổn định, nhưng các mối đe dọa đối với sự sống còn của loài này bao gồm đô thị hoá, chuyển đổi sinh cảnh cho sử dụng nông nghiệp và các nỗ lực xóa bỏ bẫy và chất độc. Nó là con mồi cho loài côn trùng ăn thịt và động vật ăn thịt ăn thịt, và có nhiều loài động vật chân đốt và sâu bướm ký sinh trùng ký sinh trùng. Các nhà khoa học tin rằng lịch sử tiến hoá của loài này đã bị gián đoạn khi trận lụt ở Missoula lụt trên thung lũng Willamette vào cuối kỷ băng hà cuối cùng. Lũ lụt gần như tràn ngập phạm vi địa lý của nó, có thể đã gây ra một nút cổ chai di truyền khi những người sống sót sau đó đã phục hồi lại khu vực sau khi các vùng nước rút đi.
Có sáu chi thú có túi ở Bắc Mỹ: 'Cratogeomys, Geomys, Orthogeomys, Pappogeomys, Thomomys, và Zygogeomys.[4]. Loài này là một loài chuột túi có răng giả của chi Thomomys, trong họ Geomyidae[5]. Các răng cửa của rêu ở chi Thomomys có bề mặt bề mặt mịn màng đặc trưng, trong khi đó các lớp của Geomys có hai rãnh sâu trên răng và của Cratogeomys có một rãnh duy nhất[6]. Loài chuột túi camas là một thành viên của phân loài Megascapheus, được thành lập vào năm 1903, vào thời điểm đó chỉ cho loài loài chuột túi camas này[5][7].
Các nhà phân loại học sau đó đã gán những người khác cho cùng phân loài[8]. Tên gọi Thomomys xuất phát từ tiếng Hy Lạp σωρός (heap) + μῦς (chuột), có thể mô tả các đống đất đào được sản xuất bởi loài chuột túi đào hố [9]. Bulbus dịch là "thân cây thảo" bằng tiếng Latinh, và từ "devour" là voro.[9] Nhà tự nhiên học David Douglas đã báo cáo rằng loài thú này ăn thân cây camas lily[10], và Vernon Bailey sau đó cho rằng thiếu hoa lily cama ở những khu vực sinh sống của gopher đến các bóng đèn được ăn. [10] Tuy nhiên, nhà tự nhiên học H. M. Wight đã quan sát thấy rằng con sói ăn chủ yếu là cây bồ công anh, và hoài nghi rằng nó là một loài ăn nhiều thân cây[11][12].
Bài viết về một loài thuộc bộ Gặm nhấm này vẫn còn sơ khai. Bạn có thể giúp Wikipedia bằng cách mở rộng nội dung để bài được hoàn chỉnh hơn. Thomomys bulbivorus là một loài động vật có vú trong họ Chuột nang, bộ Gặm nhấm. Loài này được Richardson mô tả năm 1829. Được mô tả lần đầu tiên vào năm 1829, nó là loài đặc hữu của thung lũng Willamette ở tây bắc Oregon ở Hoa Kỳ. Loài ăn cỏ gopher ăn cỏ cho rau và thực vật, nó thu thập trong túi má ngoài lớn, bên ngoài là lớp lông, bên ngoài má túi. Thức ăn dư thừa được lưu giữ trong một hệ thống đường hầm ngầm rộng lớn. Màng màu xám đậm đến xám xỉn thay đổi màu sắc và kết cấu trong suốt năm. Các răng cửa rộng và đặc trưng của động vật có vú này đặc biệt thích hợp cho việc sử dụng trong xây dựng đường hầm, đặc biệt là ở đất sét cứng của Thung lũng Willamette. Những con vượn cáo làm cho tiếng nói nghẹn lại với răng; Con đực và con cái tạo âm thanh lẩm bẩm (gợi tình) khi chúng ở bên nhau. Con non sinh ra không có răng, mù và không có lông, con non trưởng thành nhanh chóng trước khi cai sữa vào khoảng sáu tuần tuổi. Mặc dù loài này phòng thủ dữ dội khi bị dồn vào, nó có thể trở nên thuần hóa trong tình trạng bị bắt. Mặc dù xu thế dân số nói chung ổn định, nhưng các mối đe dọa đối với sự sống còn của loài này bao gồm đô thị hoá, chuyển đổi sinh cảnh cho sử dụng nông nghiệp và các nỗ lực xóa bỏ bẫy và chất độc. Nó là con mồi cho loài côn trùng ăn thịt và động vật ăn thịt ăn thịt, và có nhiều loài động vật chân đốt và sâu bướm ký sinh trùng ký sinh trùng. Các nhà khoa học tin rằng lịch sử tiến hoá của loài này đã bị gián đoạn khi trận lụt ở Missoula lụt trên thung lũng Willamette vào cuối kỷ băng hà cuối cùng. Lũ lụt gần như tràn ngập phạm vi địa lý của nó, có thể đã gây ra một nút cổ chai di truyền khi những người sống sót sau đó đã phục hồi lại khu vực sau khi các vùng nước rút đi.
카마스흙파는쥐 또는 카마스주머니고퍼(Thomomys bulbivorus)는 흙파는쥐과에 속하는 설치류의 일종이다.[2] "카마스쥐" 또는 "윌라메트계곡고퍼"로도 불린다. 1829년에 처음 기술되었고, 미국 오리건주 북서부 윌라메트 계곡의 토착종이다.
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