Pappogeomys bulleri
Buller's pocket gopher

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, Medellin, and Cameron, 2003)

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, Medellin, and Cameron, 2003)

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. (Akersten, 1973; Chapman and Feldhamer, 1982; Demastes et al., 2003; Goldman, 1939; Soler-Frost, Medellin, and Cameron, 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, Medellin, and Cameron, 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, Medellin, and Cameron, 2003)

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)

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, Medellin, and Cameron, 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)

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)

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)

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, Medellin, and Cameron, 2003)

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)

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)

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)

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)

Pappogeomys bulleri populations are currently stable.