View source for Camas pocket gopher

{{short description|Small species of burrowing rodent from Oregon}}
{{Featured article}}
{{Use dmy dates|date=December 2020}}
{{speciesbox
| name              = Camas pocket gopher
| image             = Camas pocket gopher (3).JPG
| image_alt         = A defensively postured dull brown gopher, bearing large protuberant incisors
| status            = LC
| status_system     = IUCN3.1
| status_ref        = {{sfn|Cassola|2016}}
| genus             = Thomomys
| parent            = Thomomys (Megascapheus)
| species           = bulbivorus
| authority         = ([[John Richardson (naturalist)|Richardson]], [[:Category:Animals described in 1829|1829]])
| range_map         = Camas pocket gopher species distribution.svg
| range_map_alt     = Distribution of the camas pocket gopher in the [[Willamette Valley]] of northwest Oregon
| range_map_caption = Distribution of the camas pocket gopher in the [[Willamette Valley]] of northwest Oregon
| synonyms          = {{collapsible list|bullets = true|title=<small>List</small>
|''Diplostoma bulbivorum''<br /><small>Richardson, 1829</small>
|''Diplostoma douglasii''<br /><small>Richardson, 1829</small>
|''Geomys bulbivorus''<br /><small>Richardson, 1837</small>
|''Ascomys bulbivorus''<br /><small>Wagner, 1843</small>
|''Pseudostoma bulbivorum''<br /><small>Audubon & Bachmann, 1854</small>
|''Geomys (Thomomys) bulbivorus''<br /><small>Giebel, 1855</small>
|''Thomomys bulbivora''<br /><small>Brandt, 1855</small>
|''Thomomys bulbivorus''<br /><small>Baird, 1858</small>
|''Thomomys (subgenus Megascapheus) bulbivorus''<br /><small>[[Daniel Giraud Elliot|Elliot]], 1903</small>}}
| synonyms_ref = {{sfn|Bailey|1915|p=40}}
}}

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 (biology)|family]] [[Geomyidae]]. First described in [[:Category:Animals described in 1829|1829]], it is [[endemic]] to the [[Willamette Valley]] of northwestern [[Oregon]] in the United States. The [[herbivore|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 [[burrow|tunnels]]. The dull-brown-to-lead-gray [[coat (animal)|coat]] changes color and texture over the year. The [[mammal]]'s characteristically large, protuberant [[incisor]]s 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 [[pest control|attempts at eradication]] with trapping and poisons. It is [[predation|prey]] for [[raptor (bird)|raptors]] and [[carnivore|carnivorous]] mammals, and [[host (biology)|host]] to several parasitic [[arthropod]]s 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 glacial period|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.{{Citation needed|date=April 2023}}

== Taxonomy ==
There are six [[genus|genera]] of North American pocket gophers: ''[[Cratogeomys]]'', ''[[Geomys]]'', ''[[Orthogeomys]]'', ''[[Pappogeomys]]'', ''[[Thomomys]]'', and ''[[Zygogeomys]]''.{{sfn|Patton|2005|pp=859–870}} The camas pocket gopher is a smooth-toothed pocket gopher of the genus ''Thomomys'', within the pocket-gopher family Geomyidae.{{sfn|Patton|2005|p=868}} 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.{{sfn|Elbroch|2006|p=296}} The camas pocket gopher is a member of the subgenus ''Megascapheus'', established in 1903, at that time for the camas pocket gopher alone.{{sfn|Patton|2005|p=868}}{{sfn|Verts|Carraway|1987|p=1}} Taxonomists subsequently assigned other gophers to the same subgenus.<ref name="Thomomys (Megascapheus) ITIS">{{ITIS|id=900156|taxon=''Thomomys (Megascapheus)''|access-date=14 November 2014}}</ref> The name ''Thomomys'' derives from the [[Ancient Greek|Greek]] ''[[wikt:σωρός|σωρός]]'' (heap) + ''[[wikt:μῦς|μῦς]]'' (mouse), probably describing the mounds of excavated soil produced by the burrowing gopher.{{sfn|Verts|Carraway|1987|p=4}} ''[[wikt:bulbus|Bulbus]]'' translates as "bulb" in Latin, and the word for "devour" is ''[[wikt:voro|voro]]''.{{sfn|Verts|Carraway|1987|p=4}}  Naturalist [[David Douglas (botanist)|David Douglas]] reported that the gopher consumed bulbs of the [[Camassia quamash|camas lily]],{{sfn|Richardson|1829|p=206}} and [[Vernon Orlando Bailey|Vernon Bailey]] later attributed the lack of camas lilies in areas inhabited by the gopher to the bulbs being eaten.{{sfn|Verts|Carraway|1987|p=3}} However, naturalist H. M. Wight observed that the gopher ate primarily dandelion greens, and was skeptical that it was a large consumer of bulbs.{{sfn|Verts|Carraway|1987|p=3}}{{sfn|Wight|1918|p=12}}

=== Early history ===
[[File:Camas rat.jpg|thumb|right|alt=Audubon print of four gophers beside a burrow, near a river bank|Nineteenth-century naturalists referred to a "camas rat", as in this [[James Audubon]] print.]]
The taxonomy of the camas pocket gopher and its genus, ''Thomomys'', have a convoluted history.{{sfn|Allen|1893|p=53}} 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.{{sfn|Verts|Carraway|1987|p=1}} In the 1855 article, Brandt refers to ''Tomomys bulbivora'' without the "h" and ending with an "a".{{sfn|Brandt|1855|p=188}} He writes parenthetically "(man schreibe nicht ''Thomomys'')".{{sfn|Brandt|1855|p=189}} 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.{{sfn|Verts|Carraway|1987|p=1}}

Early confusion arose from writings by [[John Richardson (naturalist)|John Richardson]] between 1828 and 1839.{{sfn|Allen |1893|pp=53–64}} Although he describes six species in the genus, according to later critics he was unfamiliar with all specimens.{{sfn|Allen|1893|p=53}} Richardson's descriptions of the animals and the figures in the text were also criticized.{{sfn|Allen|1893|p=53}} 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.{{sfn|Richardson|1829|p=206}}{{sfn|Allen|1893|p=55}} This was probably [[Portland, Oregon|Portland]], at the [[confluence]] of the Willamette and Columbia Rivers, the only place on the Columbia where subsequent specimens have been found.{{sfn|Bailey|1915|p=40}} The present location of this initial specimen is uncertain;{{sfn|Bailey|1915|p=40}} reportedly stored at the Hudson Bay Museum, it could not be located in 1915.{{sfn|Bailey|1915|p=40}} When Richardson made his first examination, the specimen was apparently incomplete;{{sfn|Allen|1893|p=53}} although [[Joel Asaph Allen]] wrote in 1893 that it consisted only of the skin,{{sfn|Allen|1893|p=56}} Richardson described the skull and facial features in detail.{{sfn|Richardson|1829|pp=206–207}}

In ''Fauna boreali-americana'', Richardson assigns the mammal to the now-defunct genus ''Diplostoma'' described by Rafinesque in 1817.{{sfn|Richardson|1829|p=206}} He named it ''Diplostoma ? bulbivorum''.{{sfn|Allen|1893|p=53}} Illustration-labeling errors in Richardson's book further confounded subsequent taxonomists; the plate was labeled ''Diplostoma douglasii''.{{sfn|Allen|1893|p=53}}

{{Blockquote|text=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 {{Sic|hide=y|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 [[Constantine Samuel Rafinesque|M Rafinesque-Schmaltz]].|author=John Richardson|source=''Fauna boreali-americana'', 1829{{sfn|Richardson|1829|p=206}}}}

{{Multiple image|total_width=330|direction= horizontal
|image1=Diplostoma douglasii (syn. Thomomys bulbivorus).jpg
|alt1=Woodcut of large gopher from 1829 book
|caption1=''Diplostoma douglasii'' from ''Fauna boreali-americana'', 1829
|image2=AmCyc Gopher - California Gopher.jpg
|alt2=Drawing of gopher on its haunches, with inset drawings of mouth, paws and nails
|caption2=Woodcut from 1879 encyclopedia article
}}

The confusion around the species' taxonomy and identification amplified when naturalist [[Spencer Fullerton Baird]] interpreted Richardson's reports.{{sfn|Allen|1893|p=56}} The camas pocket gopher's large size led Baird to conclude that the animal's measurements (reported by Richardson) were an [[artifact (error)|artifact]] of its taxidermy preparation.{{sfn|Allen|1893|pp=53–56}} Baird was also apparently in error about the location from which the specimen was taken,{{sfn|Allen|1893|p=56}} attributing the name ''Thomomys bulbivorus'' to a set of previously collected specimens later known as the California Gopher.{{sfn|Allen|1893|p=56}} This confusion was echoed by subsequent authors.{{sfn|Allen|1893|p=56}} The article on gophers in the 1879 edition of the ''[[New American Cyclopedia|American Cyclopædia]]'' has an illustration captioned "California Gopher (''Thomomys bulbivorus'')".{{sfn|Ripley|Dana|1879}} The ninth edition of the ''[[Encyclopædia Britannica]]'' (published during the late 19th century) mistakenly reports ''Thomomys bulbivorus'' as abundant along the [[Central Coast (California)|central California coast]].{{sfn|DePuy|1895|p=703}}

=== Clarifications ===

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'').{{sfn|Allen|1893|p=56}} Allen obtained and examined two large adults (male and female) collected in [[Beaverton, Oregon]], in May 1890{{sfn|Allen|1893|p=56}} which were considerably larger and darker than previously examined specimens.{{sfn|Allen|1893|p=57}} Skull features and white markings around the mouth and anus also differed.{{sfn|Allen|1893|p=57}} His findings and the specimen-collection location helped identify the camas pocket gopher as a species separate from California gophers.{{sfn|Allen|1893|p=57}} The California specimens were classified by [[Joseph Fortuné Théodore Eydoux|Eydoux]] and [[Paul Gervais|Gervais]] as ''Oryctomys bottae'', now known as ''[[Thomomys bottae]]'' (Botta's pocket gopher).{{sfn|Allen|1893|p=57}} They were found near [[Monterey, California]], over {{convert|1000|km|miles|sp=us}} south of the now-recognized range of the Camas pocket gopher.{{sfn|Allen|1893|p=57}}

[[File:Thomomys bulbivorus - Museo Civico di Storia Naturale Giacomo Doria - Genoa, Italy - DSC02780.JPG|thumb|left|alt=Stuffed gopher in museum|Taxidermied specimen in the [[Museo Civico di Storia Naturale di Genova]], mislabeled "California"]]

The distribution of [[Daniel Giraud Elliot|Elliot]]'s "great pocket gopher" (as it was known) extended along the California coast "north of San Francisco."{{sfn|Elliot|1905|p=272}} 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''.{{sfn|Audubon|Audubon|Bachman|1851|p=198}} They rejected ''Diplostoma'' as a genus, and assigned ''Diplostoma bulbivorum'' as [[synonym (taxonomy)|synonymous]] with ''P. borealis''. They attributed any differences described by Richardson to artifact, from a specimen that was "twisted and disfigured" in preparation.{{sfn|Audubon|Audubon|Bachman|1851|pp=200–201}} Based on observations of taxidermy specimens in Europe, they suggested that [[Townsend's pocket gopher]] (''Geomys (Thomomys) townsendii'') belonged to the same species.{{sfn|Audubon|Audubon|Bachman|1851|p=200}} In 1875, the camas pocket gopher was reported as a sub-species of the [[northern pocket gopher]] (''Thomomys talpoides''),.{{sfn|Coues|1875|pp=136–137}} During the 1920s H.&nbsp;M. Wight referred to it colloquially as the "Willamette Valley gopher".{{sfn|Wight|1922}}

=== Current phylogeny ===
In 2008, a team of biologists from the [[University of California, Berkeley]] and [[Harvard University]] published multilocus [[phylogenetics|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 [[taxon|taxa]] in the subgenus, but the relationships between those other animals was less clear.{{sfn|Belfiore|Liu|Moritz|2008|p=300}} Only one camas pocket gopher was included in this study, which limited the ability to distinguish features such as [[monophyly]].{{sfn|Belfiore|Liu|Moritz|2008|p=304}} The following [[cladogram]] was presented showing the placement of the camas pocket gopher among its closest relatives:{{sfn|Belfiore|Liu|Moritz|2008|p=304}}

{{clade| style=font-size:85%; line-height:85%
|label1=''[[Thomomys]]''
|{{clade
 |label1=''Thomomys''
 |1={{clade
  |1=[[Mazama pocket gopher]] (''Thomomys mazama'')
  |2={{clade
   |1=[[Idaho pocket gopher]] (''Thomomys idahoensis'')
   |2=[[Mountain pocket gopher]] (''Thomomys monticola'')
   |3=[[Northern pocket gopher]] (''Thomomys talpoides'') }} }}
 |label2=''Megascapheus''
 |2={{clade
  |1='''Camas pocket gopher (''Thomomys bulbivorus'')'''
  |2={{clade
   |1=[[Southern pocket gopher]] (''Thomomys umbrinus'')
   |2={{clade
    |1=[[Townsend's pocket gopher]] (''Thomomys townsendii'')
    |2=[[Botta's pocket gopher]] (''Thomomys bottae'') }} }} }} }} }}

Patterns of genetic variation in the camas pocket gopher have been studied.{{sfn|Carraway|Kennedy|1993|p=952}} Although there are no subspecies, there is substantial [[genetic diversity]] within the species. Its genetic patterns are consistent with limited [[inbreeding]] within specific populations.{{sfn|Carraway|Kennedy|1993|p=958}} 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.{{sfn|Carraway|Kennedy|1993|p=958}}

The species' genetic diversity is similar to that of other pocket gophers occupying a larger geographic range and diversity of habitat.{{sfn|Carraway|Kennedy|1993|p=957}} Compared to Townsend's pocket gopher, which is distributed across a much larger area, but less diverse habitat, it is more genetically heterogeneous.{{sfn|Carraway|Kennedy|1993|p=957}} Although there is considerable differentiation between separate populations of camas pocket gophers, their genetic variability does not affect the mammal's appearance.{{sfn|Carraway|Kennedy|1993|p=960}} 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.{{sfn|Carraway|Kennedy|1993|p=960}} Such an event would cause a [[population bottleneck]], leading to scattered, isolated populations.{{sfn|Carraway|Kennedy|1993|p=960}}

== Description ==
[[File:Camas pocket gopher (1).JPG|thumb|alt=Gopher baring its teeth for the camera|Camas pocket gopher at habitat-restoration site]]
The camas pocket gopher is, by a small margin, the largest member of its genus (''Thomomys'').{{sfn|Verts|Carraway|1998|p=229}} The fur is a dull brown above and dark, leaden gray beneath.{{sfn|Kays|Wilson2010|p=82}} There are often patches of white on the chin, throat and around the anus,{{sfn|Bailey|1915|p=41}} and it has blackish ear and nose markings.{{sfn|Verts|Carraway|1987|p=1}} The external ear is a thickened rim of tissue.{{sfn|Bailey|1915|p=41}} During the summer, the gopher's coat is short and coarse; winter [[pelage]] is longer and furrier.{{sfn|Verts|Carraway|1987|p=1}} The coat of the young is similar to the adult summer coat, but with more sparsely distributed fur; the abdominal skin may be visible.{{sfn|Bailey|1915|p=41}}

Like other gophers, it has small eyes and ears and a nearly hairless tail. Its shoulders are broader than its hips. It is [[dactyly|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.<!-- prior 3 sentences, same citation -->{{sfn|Verts|Carraway|1987|p=1}} The front claws of the camas pocket gopher are short and weak relative to its size.{{sfn|Bailey|1915|p=42}} It employs [[plantigrade]] locomotion. The [[sexual dimorphism|male is larger]] than the female, measuring an average {{convert|300|mm|in|abbr=on}} in length. A large male weighs about {{convert|500|g|oz|abbr=on}}.<!--  prior 3 sentences, same citation -->{{sfn|Verts|Carraway|1987|p=1}} One male specimen was {{convert|321|mm|in|abbr=on}} long and weighed {{convert|633.8|g|oz|abbr=on}}.{{sfn|Verts|Carraway|1998|p=229}} Females are about {{convert|271|mm|in|abbr=on}} long. The tail measures {{convert|90|mm|in|abbr=on}} in the male and {{convert|81|mm|in|abbr=on}} in the female. An adult male's hind feet measure {{convert|40|–|43|mm|in|abbr=on}}, and an average female's hind feet measure {{convert|39|mm|in|abbr=on}}.<!-- prior 3 sentences, same citation -->{{sfn|Verts|Carraway|1987|p=1}} There are four [[mammary gland]]s: two in the inguinal region and two in the pectoral region, each supplying a pair of nipples.{{sfn|Bailey|1915|p=40}} [[Morphology (biology)|Morphologically]], it most closely resembles [[Botta's pocket gopher]];{{sfn|Bailey|1915|p=41}} differentiation can be made based on the concavity of the inner surface of the pterygoids, small claws, more uniform fur coloring and [[Occipital bone|exoccipital]] groove of the camas pocket gopher.{{sfn|Bailey|1915|p=32}}{{sfn|Bailey|1915|p=36}}

=== Skull and dentition ===
[[File:Thomomys bulbivorus skulls.png|thumb|left|alt=Dorsal and ventral views of a camas gopher skull|Camas pocket gopher skull (Bailey, 1915)]]
The skull of the camas pocket gopher is sturdily proportioned.{{sfn|Bailey|1915|p=32}} The camas pocket gopher and other smooth-toothed pocket gophers with robust [[snout]]s are included in the subgenus ''Megascapheus''.{{sfn|Verts|Carraway|1998|p=229}} Male skulls measure {{convert|52|mm|in|abbr=on}} in length across the base and {{convert|57|mm|in|abbr=on}} if the incisors are included. The short, wide skull has a relatively short nasal passage. In width, the skull measures {{convert|19|mm|in|abbr=on}} across the nasal passages, {{convert|30.5|mm|in|abbr=on}} across the [[mastoid part of the temporal bone|mastoids]] and {{convert|36.5|mm|in|abbr=on}} at the [[zygomatic arch]]es.<!-- prior 3 sentences, same citation -->{{sfn|Verts|Carraway|1987|p=1}} The [[external auditory meatus]] is broad and open, although the [[auditory bullae]] are confined.{{sfn|Bailey|1915|p=41}}

The dentition of the camas pocket gopher is symmetric, with one set of incisors, one set of [[premolar]]s, and three sets of [[molar (tooth)|molars]] above and below. This gives a [[Dentition#Dental formula|dental formula]] of {{DentalFormula|upper=1.0.1.3|lower=1.0.1.3}}, for a total of 20 teeth.{{sfn|Verts|Carraway|1987|p=1}} The slender incisors are prominent and distinctive, smooth with yellow [[tooth enamel|surface enamel]] and white tips due to soil abrasion.{{sfn|Bailey|1915|p=41}} These distinctive, large, protuberant upper incisors give the gopher a buck-toothed appearance.{{sfn|Verts|Carraway|1987|p=1}}{{sfn|Kays|Wilson2010|p=82}} 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 [[dental alveolus|alveolar]] length of {{convert|10|mm|in|abbr=on}}.<!-- prior 3 sentences, same citation -->{{sfn|Verts|Carraway|1987|p=1}}

=== Cheek pouches ===
[[File:Thomomys bulbivorus Brandt, Johann Friedrich 1855.JPG|thumb|alt=Drawings of parts of a gopher skull|Additional views of the skull and dentition (Brandt, 1855)]]
Gophers are burrowing rodents of the family Geomyidae, characterized by fur-lined, external cheek pouches used to gather and transport food.{{sfn|Vaughan|Ryan|Czaplewski|2011|p=207}} The cheek pouches of geomyids such as the camas pocket gopher are controlled by a set of muscles,{{sfn|Merriam|1895|p=101}} 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.{{sfn|Merriam|1895|p=101}} These retractor muscles extend back and up from the cheek surfaces, forming a band {{convert|7|-|10|cm|in|abbr=on}} long and about {{convert|2|cm|in|abbr=on}} wide{{sfn|Verts|Carraway|1987|p=1}} attached to [[aponeurosis]] of the [[latissimus dorsi]] muscle.{{sfn|Merriam|1895|p=101}}

=== Male genitalia ===
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—{{convert|1.5|mm|in|abbr=on}} high, {{convert|1.8|mm|in|abbr=on}} wide at the base and {{convert|8.5|mm|in|abbr=on}} long—the examiner did not know if the specimen had reached full maturity.<!-- prior 2 sentences, same citation -->{{sfn|Verts|Carraway|1987|pp=1–2}} Subsequent reports averaged about {{convert|2.1|mm|in|abbr=on}} high, {{convert|2.2|mm|in|abbr=on}} wide at the base and {{convert|10.1|mm|in|abbr=on}} long.{{sfn|Verts|Carraway|1987|p=2}} The phallus' total length averaged {{convert|13.5|mm|in|abbr=on}}, with the [[glans]] covering more than half its length.{{sfn|Verts|Carraway|1987|p=1}}

== Distribution and habitat ==
[[File:Camassia quamash 6374.JPG|thumb|upright|alt=Image of ''Camassia quamash'', the perennial herb with deep blue inflorescence|Some argued that the camas pocket gopher consumed bulbs of the camas flower.]]
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]].{{sfn|Verts|Carraway|1987|p=1}} Its range extends north from Eugene to Portland and Forest Grove and west to [[Grand Ronde, Oregon|Grand Ronde]].{{sfn|Bailey|1915|p=40}} 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.{{sfn|Verts|Carraway|1987|p=1}}

The clay-rich Willamette Valley soils are hard in the dry season, and the gopher's protuberant incisors are well adapted to these conditions.{{sfn|Bailey|1915|p=41}} 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 community|seral communities]] of grasses and shrubs. They are also established in agricultural fields in the Willamette Valley, including fields of [[alfalfa]], [[wheat]] and [[oat]]s. The species has also been found in areas of [[disturbance (ecology)|ecological disturbance]] with similar terrain features.<!-- last 4 sentences, same ref -->{{sfn|Verts|Carraway|1998|pp=229–231}}

On a geologic timescale, the Willamette Valley has been the site of massive floods.{{sfn|Carraway|Kennedy|1993|p=959}} During the late [[Wisconsin glaciation]], a series of floods (known as the [[Missoula Floods|Missoula]] or Bretz Floods) occurred.{{sfn|Carraway|Kennedy|1993|p=959}} The last flood in the series, a massive flood with an estimated {{convert|1693|km3|abbr=on}} of water flowing at a rate of 42&nbsp;km<sup>3</sup> per hour (412&nbsp;million ft<sup>3</sup> per second) over a 40-hour period,{{sfn|Carraway|Kennedy|1993|p=959}} occurred about 13,000 years ago. The flood filled the Willamette Valley to a depth of about {{convert|122|m|ft|abbr=on}}, in a near-perfect overlay of the camas pocket gopher's range.{{sfn|Carraway|Kennedy|1993|p=958}} Although the species has been collected above this elevation, such finds are uncommon.{{sfn|Verts|Carraway|1998|pp=229–231}} A temporary lake, [[Lake Allison]], formed.{{sfn|Carraway|Kennedy|1993|p=958}} Although it is assumed that the gopher lived in the valley before the flood, no [[fossil]]s have been recovered. The [[Chehalem Mountains]], with a peak elevation of {{convert|497|m|ft|abbr=on}}, 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.<!-- prior 4 sentences all same ref -->{{sfn|Carraway|Kennedy|1993|p=960}}

== Behavior ==
{{Blockquote|text=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.|author=H. M. Wight|source=''Economic Entomology: Pamphlets'', 1918{{sfn|Wight|1918|p=16}}}}
[[File:Camas pocket gopher mounds.JPG|thumb|left|alt=Multiple mounds of excavated earth from gopher activity, scattered over dry grass field|Camas pocket gopher mounds]]
The camas pocket gopher is a mostly solitary herbivore which is active throughout the year and does not [[hibernation|hibernate]].{{sfn|Comprehensive Report Species – ''Thomomys bulbivorus''|2014}}
The gopher spends most of its time excavating [[burrow|tunnels]] in search of food,{{sfn|Verts|Carraway|1998|p=230}} and the hard clay soils of the Willamette Valley pose a challenge.{{sfn|Verts|Carraway|1987|p=3}} 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 {{convert|240|m|yds|abbr=on}} in length. About {{convert|90|mm|in|abbr=on}} in diameter, the tunnels are up to {{convert|0.91|m|ft|abbr=on}} deep.<!-- 2 sentences, same reference -->{{sfn|Verts|Carraway|1987|p=3}} When soils are damp the gopher constructs ventilation ducts or chimney mounds (possibly unique to the species),{{sfn|Verts|Carraway|1998|p=230}} to increase ventilation.{{sfn|Verts|Carraway|1987|p=3}} The chimney mounds rise vertically {{convert|15|–|25|cm|in|abbr=on|sigfig=1}}, are open at the top and are thought to ventilate the burrows in accordance with [[Bernoulli's principle]].{{sfn|Verts|Carraway|1998|p=230}} It is not known if adjacent gopher burrowing systems interconnect.{{sfn|Verts|Carraway|1998|p=230}} 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.{{sfn|Verts|Carraway|1987|p=3}} <!-- "It is possible that in areas where the ranges overlap, the Mazama pocket gopher is found at higher elevations."  Lost citation on this note. -->

[[File:Camas pocket gopher burrow.svg|thumb|upright=1.4|alt=Drawing of elaborate tunnel system|Camas pocket gopher burrow]]
Although the species is primarily [[fossorial]], it occasionally gathers food near the entrance of a tunnel.{{sfn|Verts|Carraway|1987|p=3}} [[Dandelion]]s seem to be its favorite food, and are also used as nesting material.{{sfn|Experiment Station Record|1920}} During breeding season males will enter the tunnels of females, and males and females may make purring (or cooing) sounds when they are together.{{sfn|Verts|Carraway|1987|pp=3–4}} Mothers seem to comfort the young by softly vocalizing,{{sfn|Verts|Carraway|1987|pp=3–4}} with the young twittering in response.{{sfn|Wight|1922}}

The camas pocket gopher may behave aggressively when on the defensive, with mammalogist Vernon Orlando Bailey describing the species as "morose and savage."{{sfn|Verts|Carraway|1987|p=3}} However, it may be easily tamed in captivity;{{sfn|Verts|Carraway|1998|p=230}} the female is more readily tamed than the male.{{sfn|Wight|1918|p=3}} 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]].<!-- 2 sentences, same reference -->{{sfn|Verts|Carraway|1987|p=3}}

== Ecology ==
{| class="wikitable" style="margin: 1em auto 1em auto;"
|+ Growth and development{{sfn|Verts|Carraway|1987|pp=1–2}}
|-
! style="background:#ffdead;"|Age (weeks)
! style="background:#ffdead;"|Weight
! style="background:#ffdead;"|Length
! style="background:#ffdead;"|Description
|-
|Birth
|{{convert|6.1|g|oz|abbr=on}}
|{{convert|50|mm|in|abbr=on}}
|No hair, no teeth, no cheek pouches
|-
|2
|{{convert|23|g|oz|abbr=on}}
|{{convert|90|mm|in|abbr=on}}
|Developing hair
|-
|3
|{{convert|35.5|g|oz|abbr=on}}
|{{convert|108|mm|in|abbr=on}}
|Crawling, eat solid food
|-
|4
|{{convert|53.6|g|oz|abbr=on}}
|{{convert|123.5|mm|in|abbr=on}}
|Pockets developed
|-
|5
|{{convert|70.5|g|oz|abbr=on}}
|{{convert|153|mm|in|abbr=on}}
|Eyes open
|-
|6
|{{convert|86|g|oz|abbr=on}}
|{{convert|164|mm|in|abbr=on}}
|Weaned
|}
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.<!-- 3 prior sentences same reference -->{{sfn|Verts|Carraway|1987|p=2}} In heavily irrigated areas the breeding season may be longer, extending into early September.{{sfn|Verts|Carraway|1998|pp=229–231}} About four young are born in a [[litter (animal)|litter]], although litters as large as nine have been reported.{{sfn|Verts|Carraway|1987|p=2}} The blind, hairless, toothless offspring weigh about {{convert|6.1|g|oz|abbr=on}} and are {{convert|50|mm|in|abbr=on}} in length.{{sfn|Verts|Carraway|1987|p=2}} During their first six weeks they will begin to crawl, develop cheek pouches, open their eyes and wean from milk to solid food.{{sfn|Verts|Carraway|1987|p=2}} The young then weigh about {{convert|86|g|oz|abbr=on}} and measure {{convert|164|mm|in|abbr=on}} in length.{{sfn|Verts|Carraway|1987|p=2}} At weeks 8, 10 and 17 they will weigh {{convert|101|g|oz|abbr=on}}, {{convert|160|g|oz|abbr=on}} and {{convert|167|g|oz|abbr=on}}.{{sfn|Verts|Carraway|1987|p=2}} Some reports indicate that more than one litter may be born in a season.{{sfn|Verts|Carraway|1998|pp=229–231}} Sexual maturity probably develops by the following year's breeding season.{{sfn|Verts|Carraway|1987|p=2}} Although males are fully grown by that time, females may continue to increase in size.{{sfn|Verts|Carraway|1998|pp=229–231}}

[[File:Camas pocket gopher young.JPG|thumb|left|alt=Two black-and-white photos with four young gophers in each|Ten-day-old camas pocket gopher pups]]
There was little data as of 1998 on the longevity and mortality of the camas pocket gopher.{{sfn|Verts|Carraway|1998|pp=229–231}} 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 [[mite]]s, [[louse|lice]], [[flea]]s, [[roundworm]]s and [[flatworm]]s. The species' tougher skin may protect it from some fleas known to infest Botta's pocket gopher and the Mazama pocket gopher.<!-- 3 sentences same citation -->{{sfn|Verts|Carraway|1987|p=3}} Mites known to parasitize the camas pocket gopher include ''[[Androlaelaps geomys]]'' and ''[[Echinonyssus femuralis]]''.{{sfn|Whitaker|Walters|Castor|Ritzi|2007|pp=86}} Some authorities report ''[[Androlaelaps fahrenholzi]]'' as another parasitic mite,{{sfn|Verts|Carraway|1987|p=3}} but a later publication did not report it.{{sfn|Whitaker|Walters|Castor|Ritzi|2007|pp=13–14}} The chewing louse ''[[Geomydoecus oregonus]]'' has also been reported.{{sfn|Verts|Carraway|1987|p=3}}

Two parasitic worms first discovered in the gastrointestinal tract of camas pocket gophers are the [[nematode]] ''[[Heligmosomoides thomomyos]]'' and the [[Cestoda|cestode]] ''[[Hymenolepis tualatinensis]]''. Other worms include two nematodes and the cestode ''[[Hymenolepis horrida]]''.<!-- 2 sentences same citation -->{{sfn|Verts|Carraway|1987|p=3}}

== Human interactions ==
[[File:Threatened kincaids lupine flower.jpg|thumb|left|upright|alt=Threatened Kincaid's lupine flower|Camas pocket gopher relocation may protect threatened species of flora, such as Kincaid's lupine.]]

Camas pocket gophers cause significant economic losses, so may be treated as an agricultural [[pest (organism)|pest]]. Crops damaged include [[clover]], alfalfa and [[vetch]].{{sfn|Experiment Station Record|1920}} 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; [[potato]]es, [[carrot]]s, [[parsnip]]s 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.{{sfn|Experiment Station Record|1920}} An estimate of impact from camas pocket gopher activities in the Willamette Valley in 1918 amounted to $1.5&nbsp;million annual losses.{{sfn|Experiment Station Record|1920}} Gopher activities can provide a benefit of [[Aeration#Aeration of soil|soil aeration]], enhancing water retention after rain or snowmelt. Buried vegetation can also compost, enhancing organic soil content to provide additional benefits.{{sfn|Nowak|1999}}

Proposed methods for [[pest control|controlling]] gopher populations in agricultural areas include poisoning dandelions,{{sfn|Experiment Station Record|1920}} clover, carrots, [[sweet potato]]es and parsnips.{{sfn|Verts|Carraway|1987|p=3}} Camas pocket gophers are larger than other gophers, so conventional gopher traps may fail to capture them.{{sfn|Verts|Carraway|1987|p=3}} Toxic baits and fumigants may also fail, since the gophers will sometimes wall off a segment of the burrow.{{sfn|Verts|Carraway|1987|p=3}} Gophers may also cause local flooding if their tunneling activities damage [[levee]]s.{{sfn|Nowak|1999}}

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.{{sfn|The Camas pocket gopher – Small but fierce!}} At a site south of [[Philomath, Oregon]], the IAE is working to protect a small but viable population of [[Kincaid's lupine]] (''Lupinus sulphureus'').{{sfn|The Camas pocket gopher – Small but fierce!}} 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.{{sfn|Kincaid's lupine}}<ref name=ns>[http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Icaricia+icarioides+fenderi ''Plebejus icarioides fenderi''.] {{Webarchive|url=https://web.archive.org/web/20071004015901/http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Icaricia+icarioides+fenderi |date=4 October 2007 }} NatureServe. 2012.</ref> The gophers are relocated to a nearby location distant from the lupines.{{sfn|The Camas pocket gopher – Small but fierce!}}

=== Conservation status ===
[[File:Thomomys bulbivorus.jpg|thumb|upright|alt=Skeleton model of the camas pocket gopher in a museum display case|Skeleton at the [[Museum of Osteology]] in Oklahoma]]
Citing concerns of [[urbanization]], [[habitat loss]] and active attempts at eradication, [[NatureServe]] assessed in 2014 the camas pocket gophers' conservation status as vulnerable.{{sfn|Comprehensive Report Species – ''Thomomys bulbivorus''|2014}} 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.{{sfn|Cassola|2016}} 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,{{sfn|Cassola|2016}}{{sfn|Verts|Carraway|1998|pp=229–231}} and the species may adapt well to environmental changes.{{sfn|Cassola|2016}}

The IUCN and others express concern about degradation of the species' habitat due to urbanization and [[agricultural expansion]].{{sfn|Cassola|2016}}{{sfn|Ricketts|1999|p=155}} The total area occupied by the camas pocket gopher is less than {{convert|20000|km2|sqmi|abbr=on}}.{{sfn|Cassola|2016}} This area, the Willamette Valley, contains 70 percent of Oregon's human population.{{sfn|Jewell|McRae|2011|p=9}} Although this range probably contains a few [[protected area]]s, many preserves in the valley are primarily [[waterfowl]] protection for hunters.{{sfn|Ricketts|1999|p=155}} 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),{{sfn|Verts|Carraway|1998|pp=229–231}} it may be considered a pest and subject to eradication by poisoning and trapping.{{sfn|Cassola|2016}}

== References ==
=== Footnotes ===
{{Reflist|20em}}

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{{refend}}

== External links ==
{{Portal|Mammals|Oregon}}
*{{Commons category-inline}}
*{{Wikispecies-inline|Thomomys bulbivorus}}
*{{UniProt Taxonomy | name = ''Thomomys bulbivorus''| id = 113116| access-date = 5 August 2016}}

{{Geomyidae nav}}
{{Taxonbar|from=Q1770749}}

[[Category:Thomomys|Camas pocket]]
[[Category:Endemic rodents of the United States]]
[[Category:Endemic fauna of Oregon|Camas pocket]]
[[Category:Mammals described in 1829]]
[[Category:Least concern biota of the United States]]
[[Category:NatureServe vulnerable species]]
[[Category:Willamette Valley|Camas pocket]]
[[Category:Taxonomy articles created by Polbot]]
[[Category:Taxa named by John Richardson (naturalist)]]
[[Category:Mammals of Oregon]]