Pappogeomys bulleriBuller's pocket gopher

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Geographic Range

All nine subspecies of Pappogeomys bulleri are found in western central Mexico, in the states of Nayarit, Jalisco, Colima, and Michoacan. (Demastes, et al., 2003; Soler-Frost, et al., 2003)

Habitat

Pappogyomys bulleri is a montane species that prefers soils of volcanic origin. It lives at sea level, extending into elevations as high as 3,050 m. It inhabits Jalisco, Mexico, which is well known for a variety of terrains and climates. In Jalisco, seasons are based on rainfall, with 80% of rain coming between July and October. The average monthly temperature in this region is 24.9C. Pine-Oak forests border meadows and agricultural zones. Tropical deciduous forests are also found in the region. Subspecies of P. bulleri are found in all the terrains and climates in the area. (Anderson and Jones, 1984; Ceballos, 1990; Chapman and Feldhamer, 1982; Demastes, et al., 2003; Genoways and Jones, 1969; Soler-Frost, et al., 2003)

  • Range elevation
    0 to 3050 m
    0.00 to 10006.56 ft
  • Average elevation
    1500 m
    4921.26 ft

Physical Description

The morphology of Pappogeomys bulleri is well adapted to fossorial life. They have small, flattened heads, short necks, and short, broad, and muscular forelimbs. The eyes, nose, and ears can be closed by flaps of skin to keep out dirt when digging. Their lips can close behind their incisors, allowing them to dig with their teeth and keep their mouth free of dirt. Their common name, Buller's pocket gopher, refers to the fur-lined cheek pouches in their mouths. They use these pouches to transport food from above ground into their burrows. They have large, sharp claws on their forelimbs and shorter claws on their hind feet. (Chapman and Feldhamer, 1982; Demastes, et al., 2003; Goldman, 1939; Soler-Frost, et al., 2003; Akersten, 1973; Chapman and Feldhamer, 1982; Demastes, et al., 2003; Goldman, 1939; Soler-Frost, et al., 2003)

The pelage varies by subspecies, but is generally pale to dark grey basally and tawny to cinnamon brown dorsally. Long, soft and fine, their fur lies near the body and falls in one direction. They sometimes have a white or buff nasal patch, although it is often missing. Their tails are naked and white, extending a distance less than half the length of the body and head. Pappogeomys bulleri is sexually dimorphic with males larger than females, but this difference is not as pronounced as in other gopher species (Geomyidae). Variation in size also exists among subspecies. On average, the total body length of males is 214 to 237 mm and the total body length of females is 130 to 175 mm. Males continue to grow in body size throughout their lifetime, while females stop growing at sexual maturation. Average measurements are as follows (in mm): length of head and body 130-175; length of tail 50-85; length of ear 6.5-8; length of hind food 28-35; occipitonasal length 36.2-44.0; zygomatic breadth 21.4-27.8; width across squamosals 20.3-27.2; breadth of interorbital constriction 6.5-8; length of nasals 11.8-16.2; length of maxillary toothrow 7.5-10.2; width of upper incisors at cutting edge 3.8-4.9; length of rostrum 16.6-21.4. Overall, the skull of P. bulleri is small and narrow. (Akersten, 1973; Chapman and Feldhamer, 1982; Demastes, et al., 2003; Goldman, 1939; Soler-Frost, et al., 2003)

The teeth are similar to those of other rodents and gophers. They have two large, central incisors that they use in digging. These incisors have a single, medial sulcus that runs down the entire labial surface of the tooth. Like those of other rodents, the incisors are continually worn down and regenerated. Lower incisors are regenerated significantly faster than upper incisors. The first molar has a thin enamel plate that extends across the posterior wall of the tooth and is variable among subspecies. Pocket gophers have 20 teeth total, with the dental formula: i 1/1, c 0/0, p 1/1, m 3/3. (Akersten, 1973; Chapman and Feldhamer, 1982; Demastes, et al., 2003; Goldman, 1939; Morand, et al., 2000; Soler-Frost, et al., 2003)

  • Sexual Dimorphism
  • male larger
  • Average mass
    225 g
    7.93 oz
  • Range length
    192 to 237 mm
    7.56 to 9.33 in

Reproduction

Pappogeomys bulleri is thought to have a polygynous mating system. The range of one male overlaps with those of several females but ranges of the females do not overlap. Other than interacting while mating, individuals remain solitary. (Chapman and Feldhamer, 1982; Soler-Frost, et al., 2003)

The mating season for P. bulleri is year round, with the most active period being between late winter and early summer. Mating behavior and breeding activity begins at about nine months to one year of age for both sexes. Females are sexually mature once their pubic symphysis has opened, widening the birthing canal. After the first breeding season, the pubic symphysis is completely absorbed at the command of relaxin, an ovarian hormone. Males are sexually mature when the baculum and sex glands are fully developed. (Anderson and Jones, 1984; Chapman and Feldhamer, 1982; Soler-Frost, et al., 2003)

  • Breeding interval
    Pocket gophers breed one to two times in a breeding season.
  • Breeding season
    The mating season is year round, but Pappogeomys bulleri most frequently mate in late winter, spring, and early summer.
  • Range number of offspring
    2 to 11
  • Range gestation period
    18 to 20 days
  • Range weaning age
    35 to 40 days
  • Average time to independence
    2 months
  • Range age at sexual or reproductive maturity (female)
    6 to 12 months
  • Range age at sexual or reproductive maturity (male)
    9 to 12 months

Female P. bulleri have six mammae: one pectoral pair and two lingual pairs. A female will have anywhere from 2 to 11 young in a litter. The gestation period is around 20 days. Newborn Buller's pocket gophers are altricial. On average, they weigh between 2.5 and 4 g, with cheek pouches not fully developed and eyes that are still under a thin layer of skin. In about one month, their cheek pouches, eyes and ears are opened and one week later they are able to use their cheek pouches to carry food. After two months, siblings begin to fight with one another, undergo weaning, and disperse soon afterwards. Juveniles molt to show adult pelage when they are near 100 days old. (Chapman and Feldhamer, 1982; Soler-Frost, et al., 2003)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

The maximum lifespan of pocket gophers is 5 years. The average age of individuals found in collections is 13.6 months for males and 18.6 months for females. The oldest males trapped in the wild were 4 and 5 years old, and the oldest females trapped were 4 years and 9 months. (Chapman and Feldhamer, 1982)

  • Range lifespan
    Status: wild
    5 (high) years
  • Typical lifespan
    Status: wild
    1.5 to 5 years

Behavior

Pappogeomys bulleri is highly fossorial and lives primarily in complex subterranean tunnel systems. Like other fossorial rodents, P. bulleri uses a combination of claws and incisors to help dig burrows. The burrows are dug with the animal’s entire body, and their diameter depends on the size of the individual. When digging, the gopher loosens dirt with its claws and incisors, then pushes the dirt underneath its body. The gopher then turns around and pushes the dirt to the surface. As it is digging, it uses its incisors to clip roots in the path of the burrow and its large claws to remove small rocks. Depths of the burrow system ranges from 10 to 30 cm underground and side tunnels are frequently found branched off of the main tunnel. Side tunnels are used as a place to store food. Nesting and breeding burrows are dug deeper than the main system, and the gopher lines these with dried grasses. Pocket gopher tunnel systems are closed and thus are fairly resistant to rain and flooding. Gophers open their tunnels several times per day to leave them to gather food or excavate soil, but close them again with a small mound of loosened soil deposited in a fan-shape of concentric rings. (Anderson and Jones, 1984; Ceballos, 1990; Chapman and Feldhamer, 1982; Demastes, et al., 2003; Genoways and Jones, 1969; Soler-Frost, et al., 2003; Wilkins and Woods, 1983; Wilkins, et al., 1999)

Pappogeomys bulleri is primarily solitary, living in close proximity to other members of the species only during periods of mating or while raising young. The species is active year round and can be quite aggressive to conspecifics when they encroach on another’s territory. Although P. bulleri is territorial, they are docile rodents in most situations, particularly when interacting with people. Pocket gophers are active all day, rotating between active periods and resting periods. Active periods last about 36 minutes and resting periods are about an hour. They have been observed to have 16.1 activity periods a day. (Anderson and Jones, 1984; Chapman and Feldhamer, 1982; Wilkins and Woods, 1983; Wilkins, et al., 1999)

  • Range territory size
    74 to 445 m^2

Home Range

The home ranges of P. bulleri are similar to those of other pocket gophers. Males generally have larger home ranges than females. Individuals that live closer to or under agricultural areas tend to have smaller home ranges than individuals in less developed areas. (Chapman and Feldhamer, 1982)

Communication and Perception

Pappogeomys bulleri perceives its environment primarily through sound, touch, and smell. Gophers have vibrissae around their face and wrists which aid in navigating in burrows. The ears of P. bulleri are unique when compared with other rodents. The bullae are comprised of very thick bone and show modifications in the stapes. These features are in response to their subterranean lifestyle. They do not have sensitive hearing systems for low or high frequencies, which may protect their ears from incessant underground background noises. (Anderson and Jones, 1984; Chapman and Feldhamer, 1982; Wilkins, et al., 1999)

Pappogeomys bulleri communicates with conspecifics vocally. When confronted with each other, two P. bulleri will hiss or click their teeth at each other. In captivity they are known to squeal when angry or in pain. (Anderson and Jones, 1984; Chapman and Feldhamer, 1982; Wilkins, et al., 1999)

Food Habits

Buller's pocket gophers are strictly herbivorous and eat a variety of plant foods. They prefer forbs, comprising 40% of their diet, but also eat grasses (30% of their diet) and the roots of xerophytic shrubs. They gather most food above ground, and transport it into their burrows by means of cheek pockets. Once underground, the food is either eaten or stored in sealed compartments. Occasionally, P. bulleri eats roots from inside of the burrows. Water is mainly obtained through food in the diet. (Anderson and Jones, 1984; Chapman and Feldhamer, 1982; Soler-Frost, et al., 2003)

  • Plant Foods
  • leaves
  • roots and tubers
  • wood, bark, or stems

Predation

Pappogeomy bulleri is most susceptible to predation while above ground. Pocket gophers are important prey for a variety of predators, including weasels, coyotes, birds of prey, foxes, bobcats, domestic cats, snakes, and skunks. Although snakes will live in the burrows of P. bulleri, they are physically unable to kill them while underground due to space restrictions. Avian predation has the most impact on populations of pocket gophers, but studies have found that the main selective pressures on population size are food and habitat availability, not predation. (Anderson and Jones, 1984; Chapman and Feldhamer, 1982)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Pappogeomys bulleri is important to the ecosystem in many ways. Their constant digging and burrowing work to aerate soils, slow runoff, and fertilize soils. These activities enrich the soil and increase yield of the plants the gophers like to eat. The burrows of the gophers become a habitat to other organisms as well. Reptiles, other mammals (moles, squirrels, mice, rats, voles, and weasels), and some birds benefit from their burrow systems. These pocket gophers play an important role in the ecosystem as a host for parasites, including chewing lice, fleas, mites, and ticks. Other ways in which they affect their environment are as an important prey species (see section above) and as herbivores. Large populations of pocket gophers can change plant composition in an area: their mixing of soils causes foods that pocket gophers prefer to eat increase in quantity, while the plants they choose not to eat are no longer as common. (Chapman and Feldhamer, 1982; Morand, et al., 2000)

Mutualist Species
Commensal/Parasitic Species
  • Eimeria thomomysis
  • Eimeria fitzgeraldi
  • Cysticerci
  • Paranoplocephala infrequens
  • Paranoplocephala variabilis
  • Ransomus rodentorum
  • Longistriata vexillata
  • Protospirura ascaroidea
  • Trichuris fossor
  • Capillaria hepatica
  • Cuterebra
  • Haemogamasus ambulans
  • Hirstionyssus geomydis
  • Haemolaelaps geomys
  • Ixodes sculptus
  • Geomydoecus thomoyus
  • Geomydoecus chapini
  • Foxella ignota

Economic Importance for Humans: Positive

Pappogeomys bulleri populations have a positive impact on soil fertilization and plant growth, and may help promote good soils for agriculture. (Chapman and Feldhamer, 1982)

Economic Importance for Humans: Negative

Pappogeomys bulleri are serious agricultural pests. They are known to gnaw through plastic irrigation pipes and electric cables and eat a significant portion of crops or food designated for livestock or humans. Studies have shown that gophers can reduce the foliage intended for livestock by twenty percent. Farmers in areas with high populations of gophers have developed a number of ways to deal with gophers. Poisons are lowered into the gophers burrow systems or gophers are baited and caught. Gophers are very efficient diggers, however, and are able to counter many of these strategies. Within the range of P. bulleri, many villages have a “tucero,” a person whose job it is to trap and kill gophers. This job is passed from father to son and the tucero is a respected member of the community. (Chapman and Feldhamer, 1982; Stoddart, 1979; Walker, 1975)

  • Negative Impacts
  • crop pest

Conservation Status

Pappogeomys bulleri populations are currently stable.

Contributors

Emily Kenny (author), University of Michigan-Ann Arbor, Phil Myers (editor, instructor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

folivore

an animal that mainly eats leaves.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

fossorial

Referring to a burrowing life-style or behavior, specialized for digging or burrowing.

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

polygynous

having more than one female as a mate at one time

scrub forest

scrub forests develop in areas that experience dry seasons.

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

soil aeration

digs and breaks up soil so air and water can get in

solitary

lives alone

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

tactile

uses touch to communicate

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

vibrations

movements of a hard surface that are produced by animals as signals to others

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

year-round breeding

breeding takes place throughout the year

References

Akersten, W. 1973. Upper Incisor Grooves in the Geomyinae. Journal of Mammalogy, 54 (2): 349-355.

Anderson, S., J. Jones. 1984. Orders and Families of Recent Mammals of the World. United States of America: John Wiley & Sons, Inc..

Ceballos, G. 1990. Journal of Mammalogy. Comparative Natural History of Small Mammals from Tropical Forests in Western Mexico, 71 (2): 263-266.

Chapman, J., G. Feldhamer. 1982. Wild Mammals of North America: Biology, Management, and Economics. Baltimore: The Johns Hopkins University Press.

Demastes, J., A. Butt, M. Hafner, J. Light. 2003. Systematics of a Rare Species of Pocket Gopher, Pappogeomys alcorni. Journal of Mammalogy, 84 (2): 753-761.

Genoways, H., J. Jones. 1969. Notes on Pocket Gophers from Jalisco, Mexico, with Descriptions of Two New Subspecies. Journal of Mammalogy, 50 (4): 748-755.

Goldman, E. 1939. The Pocket Gophers of the Genus Pappogeomys. Journal of Mammalogy, 20 (1): 93-98.

Honeycutt, R., S. Williams. 1982. Genic Differentiation in Pocket Gophers of the Genus Pappogeomys, with Comments on Intergeneric Relationships in the Subfamily Geomyinae. Journal of Mammalogy, 63(2): 208-217.

Morand, S., M. Hafner, R. Page, D. Reed. 2000. Comparative body size relationships in pocket gophers and their chewing lice. Biological Journal of the Linnean Society, 70: 239-249.

Soler-Frost, A., R. Medellin, G. Cameron. 2003. Mammalian Species: Pappogeomys bulleri . American Society of Mammalogists, 717: 1-3.

Stoddart, D. 1979. Ecology of Small Mammals. Cambridge: University Press.

Walker, E. 1975. Mammals of The World, Third Edition. Baltimore: The Johns Hopkins University Press.

Wilkins, K., J. Roberts, C. Roorda, J. Hawkins. 1999. Morphometrics and Functional Morphology of Middle Ears of Extant Pocket Gopher (Rodentia: Geomyidae). Journal of Mammology, 80 (1): 180-198.

Wilkins, K., C. Woods. 1983. Modese of Mastication in Pocket Gophers. Journal of Mammalogy, 64 (4): 636-641.