Zapus trinotatus, Rhoads, 1895

Don E. Wilson, Russell A. Mittermeier & Thomas E. Lacher, Jr, 2017, Zapodidae, Handbook of the Mammals of the World – Volume 7 Rodents II, Barcelona: Lynx Edicions, pp. 50-61 : 58

3.

Pacific Jumping Mouse

Zapus trinotatus

French: Zapode du Pacifique / German: Pazifik-Hipfmaus / Spanish: Raton saltador del Pacifico

Other common names: Coast Jumping Mouse; Point Reyes Jumping Mouse (orarius)

Taxonomy. Zapus trinotatus Rhoads, 1895 ,

“ Lulu Island (mouth of Frazier River), British Columbia,” Canada .

Zapus apparently arose in Asia from an Eozapus ancestor that had moved across the Bering Strait into North America and gave rise to Z. rinkeri (the first known Zapus ), then Z. burti and Z. hudsonius , which gave rise to Napaeozapus . Zapus burti may then have given rise to Z. trinotatus and Z. princeps . Four subspecies recognized.

Subspecies and Distribution.

Z.t.trinotatusRhoads,1895—SWCanada(extremeSWBritishColumbia)andNWUSA(WWashington,andalongthePacificcoastofOregontoextremeNWCalifornia).

Z.t.eurekaA.B.Howell,1920—WUSA(coastalNCalifornia).

Z.t.montanusMerriam,1897—NWUSA(inlandNW&WCOregon).

Z. t. orarius Preble, 1899 — W USA (small area of coastal California just N of San Francisco Bay).

Descriptive notes. Head-body 89-102 mm, tail 112-155 mm, hindfoot 30-60 mm; weight 12-38 g. Pacific Jumping Mice can be distinguished from other species of Zapus by their slightly largersize and largerfirst molariform teeth (0-70 mm x 0-75 mm). They also have distinct separation of colors between dorsum and ventrum. As in other zapodids,tail is very long, and hindfeet and legs are much larger than front feet. Colors are striking, generally brighter than in the Western Jumping Mouse ( Z. princeps ) or Meadow Jumping Mouse ( Z. hudsonius ). Dorsum is dark brown to cinnamon, sides are orange brown or ocherous tinged buff, and both are interspersed with dark guard hairs. Ears are relatively short and well haired, and ear fringe is light brown or same color as dorsum. Dark brownish band runs down middle of back. Underparts are typically white but sometimes have dusky brown tinge. Tail is dark brown on top and whitish below. Color is paler and shows less contrast in autumn. Skull is broad. Infraorbital foramen is large and oval. Zygomatic plate is nearly horizontal rather than oblique and is narrower than, and completely beneath, infraorbital foramen. Nasal bones project considerably beyond incisors. Incisive foramina of rostrum are long. Incisors are orange or yellow, and upper incisors contain deep grooves on anterior surfaces. There are four upper molariform teeth, and first premolaris reduced. Molars are rooted and flatcrowned and have complicated patterns of re-entrant folds,islands, and valleys. The Pacific Jumping Mouse is similar to the Western Jumping Mouse, but allozymic differences show that specific designation is warranted. Dental formulaisI11/1,C0/0,PM1/0,M 3/3 (x2) = 18.

Habitat. Many meadows, including alpine meadows, and often in alder ( Alnus , Betulaceae ) and salmonberry ( Rubus spectabilis, Rosaceae ) riparian deciduous woodlands. Pacific Jumping Mice also inhabit skunk cabbage ( Lysichiton americanus , Araceae ) marshes along coastal redwood ( Sequoia sempervirens, Cupressaceae ) and Douglas fir ( Pseudotsuga menziesii, Pinaceae ) forests. They also occur in a variety of other habitats including prairie; scrub; mixed evergreen forests; rush, sedge, and fern habitats; various grassy situations; poison hemlock ( Conium maculatum, Apiaceae ); and monkey grass ( Liriope , Asparagaceae ). High moisture (more than 300 mm of rainfall per year) favors the Pacific Jumping Mouse. It is isolated from the Western Jumping Mouse by a north/south strip of dry habitat.

Food and Feeding. The Pacific Jumping Mouse, like other species of Zapus and the Woodland Jumping Mouse ( Napaeozapus insignis ), are basically granivorous, with seeds constituting at least 50% of their diet. Seeds eaten include velvet grass ( Holcus lanatus, Poaceae ), dock ( Rumex , Polygonaceae ), and skunk cabbage. As with the other species of Zapus , Pacific Jumping Mice will cut sections from stems and pull them down until seed heads can be reached. Stem sections are left in tiny stacks on the ground with rachis on top of the pile. They feed heavily on fungi, including Glomus, Sclerocystis, and Endogonaceae . They also eat many differentfruits in season, such as blackberry ( Rubus , Rosaceae ), gooseberry ( Ribes , Grossulariaceae ), and blueberry ( Vaccinium , Ericaceae ). Catepillars can make up to 13-4% of diets, and other insects can form 3-5—6-3% of diets. Few internal parasites have been reported. Protozoans include Trypanosoma zapi in blood and Eimeria zapi cysts in feces. Mites, other than chiggers, include species of Glycyphagidae, Glycyphagus hypudaer, G. newyorkensis; Laelapidae, Androlaelaps fahrenholzi, Echinonyssus isabellinus, Haemogamasus ambulans, H. occidentalis, and H. reidi; Macrochelidae, Macrocheles praedafimetorum; Myobiidae, Radfordia ewingr, and Myocoptidae, Gliricoptes zapus. Chiggers include Trombiculidae and Leewenhoekiidae: Euschoengastia peromysci, Neotrombicula jewetti, and Shunsennia ochotona. Ticks include Ixodidae , Ixodes angustus. Fleas include Megabothris abantis and M. quirini. There was a 3-1% occurrence of the Pacific Jumping Mouse remains in barn owls’ (7yto alba) pellets in British Columbia. It was nearly 2% of the diet of the long-eared owl (Asio otus), 16% of the diet of the barn owl, and 0-21% of the great horned owl (Bubo virginianus) in western Oregon. Four Pacific Jumping Mice were found among remains of 338 vertebrates in three barn owl nests in the San Francisco area of California. Bobcats (Lynx rufus) and domestic cats feed upon jumping mice, and many other predators certainly feed on them when available.

Breeding. Pacific Jumping Mice have one annuallitter of 4-8 young. Males become sexually active in May-June and sometimes as late as September. Females mate in May-June and usually give birth in July-August. Nests are built underground or on the surface in dense cover. One nest was found in the crook of a coastal redwood, c.1:4 m above the ground. It was 14-5 cm in diameter and lined with grass. It contained five early stage young. Another Pacific Jumping Mouse took over a nest of a dark-eyed junco (Junco hyemalis), ate the four eggs, lined the nest with egg shells, and built a dome over the nest with dry grass and Wapiti (Cervus canadensis ) hair. Gestation is 18-23 days. Newborn are pink and hairless with eyes shut and ears folded. They lack vibrissae and weigh 0-7-0-9 g.

Activity patterns. Specialization for jumping includes well developed hindlegs and feet and very long tails that provide balance. Pacific Jumping Mice can jump up to c.1 m. An individual lacking a tail jumped 35 cm high and 1 m forward, but it turned somersaults and landed on its back several times; it was unable to control itself. Pacific Jumping Mice produce a squeaking noise when fighting, and they will vibrate their tail producing a drumming noise when excited. They swim well. In autumn, Pacific Jumping Mice use vacant burrows or make their own for hibernation. Burrows can be found up to 76 cm below the surface and are often connected at a central chamber. Chambers are c.13 cm wide, with an entrance hole of c.4 cm. Nests may be close together and have been found with connecting tunnels. In preparation for hibernation, Pacific Jumping Mice accumulate large amounts of fat and may double their weights. They rely on energy derived from their body fat stores to see them through hibernation; they do not cache food items. Pacific Jumping Mice hibernate with their tail curled around the body and head. Emergence from hibernation is about mid-April.

Movements, Home range and Social organization. Populations of Pacific Jumping Mouse undergo periodic fluctuations, sometimes occurring in unusually high abundance. A. B. Howell in 1923 reported having found them as “fairly swarming” in the Cascade Mountains of Washington when they had been scarce the previous year. Pacific Jumping Mice formed 6% of the small mammal community in Lane County, Oregon, but populations vary greatly among habitats and through time. Largest populations are found where rainfall is highest. Common small mammal associates are Meadow Voles ( Microtus pennsylvanicus), deer mice, shrews, shrew-moles, and Mountain Beavers (Aplodontia rufa).

Status and Conservation. Classified as Least Concern on The IUCN Red List. Population trends are unknown. Subspecies orarius has a very small distribution;it is a candidate for US federal protection and of special conservation concern in California.

Bibliography. Cooley & Kohls (1945), Dalquest (1948), Davis (1952), Dawe et al. (1978), Duszynski et al. (1982), Fain & Whitaker (1974), Flahaut (1939), Gannon (1988, 1999), Holland (1949), Howell (1923), Hubbard (1941, 1947), Jameson & Brennan (1957), Jones (1981), Jones et al. (1978), Krantz & Whitaker (1988), Krutzsch (1954), Maser & Brodie (1966), Maser & Franklin (1974), Maser, Mate et al. (1981), Maser, Trappe & Nussbaum (1978), Myers (1969), Reynolds (1970), Smith & Hopkins (1937), Svihla & Svihla (1933), Taylor (1922), Whitaker (1979), Whitaker & Maser (1985).

Figures

1. Chinese Jumping Mouse (Fozapus setchuanus), 2. Meadow Jumping Mouse (Zapus hudsonius), 3. Pacific Jumping Mouse (Zapus trinotatus), 4. Western Jumping Mouse (Zapus princeps), 5. Woodland Jumping Mouse (Napaeozapus insignis)

Subspecies and Distribution. Z.t.trinotatusRhoads,1895—SWCanada(extremeSWBritishColumbia)andNWUSA(WWashington,andalongthePacificcoastofOregontoextremeNWCalifornia). Z.t.eurekaA.B.Howell,1920—WUSA(coastalNCalifornia). Z.t.montanusMerriam,1897—NWUSA(inlandNW&WCOregon). Z. t. orarius Preble, 1899 — W USA (small area of coastal California just N of San Francisco Bay).