Cricetidae Author Don E. Wilson Author Russell A. Mittermeier Author Thomas E. Lacher, Jr text 2017 2017-11-30 Lynx Edicions Barcelona Handbook of the Mammals of the World – Volume 7 Rodents II 204 535 book chapter 80832 10.5281/zenodo.6707142 ab66b2b7-9544-4411-bf61-5bc3651d7bca 978-84-16728-04-6 6707142 210. Northern Pygmy Mouse Baiomys taylori French: Baiomys de Taylor / German: Nordliche Amerikanische Zwergmaus / Spanish: Raton pigmeo septentrional Taxonomy. Hesperomys (Vesperimus) taylor Thomas, 1887 , “San Diego, [Duval County], South Texas ,” USA . Eight subspecies are recognized. Subspecies and Distribution. B.t.taylorThomas,1887—fromNTexas(SUSA)SalongtheEcoastofMexicotoNVeracruzState. B.t.allexOsgood,1904—SNayarit,W&CJalisco,Colima,andSWMichoacan(WMexico). B.t.analogusOsgood,1909—fromEJaliscoEtoCEPuebla(SCMexico). B.t.aterBlossom&Burt,1942—SEArizonaandSWNewMexico(SWUSA),andNESonoraandNWChihuahuastates(NWMexico). B.t.canutusPackard,1960—SSonora,Sinaloa,andNWNayaritstates(NWMexico). B.t.fuliginatusPackard,1960—ESanLuisPotosiState(CMexico). B.t.paulus|.A.Allen,1903—fromNCChihuahuaStoNGuanajuatostates(NW&WCMexico). B. t. subater Bailey, 1905 — EC Texas (S USA). Descriptive notes. Head-body 53-76 mm, tail 34-53 mm, ear 9-12 mm, hindfoot 12-15 mm; weight 6-9 g. The Northern Pygmy Mouse is one of the smallest species of mice in North America. Dorsum is reddish brown to dark gray or black; venter is gray, with white or cream highlights. Tail color differs among subspecies and can be gray or bicolored. The Northern Pygmy Mouse differs from the Southern Pygmy Mouse ( B. musculus ) by size of hindfeet (less than 16 mm) and average length of baculum, which is significantly shorter and thinner in the Northern Pygmy Mouse. Habitat. Grasslands, xeric scrublands, thorn forests, forests of oak ( Quercus , Fagaceae ) and conifers, and croplands from sea level to elevations of ¢.2450 m. Northern Pygmy Mice are found mainly in dense grasslands or grassy areas. On following pages: 211. Short-tailed Singing Mouse ( Scotinomys teguina ); 212. Long-tailed Singing Mouse ( Scotinomys xerampelinus ); 213. Yellow Deermouse ( Isthmomys flavidus ); 214. Mount Pirri Deermouse (/sthmomys pirrensis ); 215. Florida Deermouse ( Podomys floridanus ); 216. Volcano Deermouse ( Neotomodon alstoni ); 217. Short-nosed Harvest Mouse ( Reithrodontomys brevirostris ); 218. Darien Harvest Mouse ( Reithrodontomys darienensis ); 219. Slender Harvest Mouse ( Reithrodontomys gracilis ); 220. Mexican Harvest Mouse ( Reithrodontomys mexicanus ); 221. Nicaraguan Harvest Mouse ( Reithrodontomys paradoxus ); 222. Cozumel Harvest Mouse ( Reithrodontomys spectabilis ); 223. Talamancan Harvest Mouse ( Reithrodontomys crepen; 224. Rodriguez's Harvest Mouse ( Reithrodontomys rodriguez); 225. Narrow-nosed Harvest Mouse (Reithrodontomys tenuirostris); 226. Small-toothed Harvest Mouse ( Reithrodontomys microdon ); 227. Costa Rican Harvest Mouse ( Reithrodontomys cherrii ); 228. Chiriquian Harvest Mouse ( Reithrodontomys garichensis); 229. Musser's Harvest Mouse ( Reithrodontomys musseri ); 230. Baker's Harvest Mouse ( Reithrodontomys bakeri ); 231. Fulvous Harvest Mouse ( Reithrodontomys fulvescens ); 232. Hairy Harvest Mouse ( Reithrodontomys hirsutus ); 233. Sonoran Harvest Mouse ( Reithrodontomys burti ); 234. Volcano Harvest Mouse ( Reithrodontomys chrysopsis ); 235. Eastern Harvest Mouse ( Reithrodontomys humulis ); 236. Western Harvest Mouse ( Reithrodontomys megalotis ); 237. Plains Harvest Mouse ( Reithrodontomys montanus); 238. Salt-marsh Harvest Mouse (Reithrodontomys raviventris); 239. Sumichrast’s Harvest Mouse (Reithrodontomys sumichrasti ); 240. Zacatecan Harvest Mouse ( Reithrodontomys zacatecae ); 241. Chihuahuan Grasshopper Mouse ( Onychomys arenicola ); 242. Northern Grasshopper Mouse ( Onychomys leucogaster ); 243. Southern Grasshopper Mouse ( Onychomys torridus ); 244. Osgood's Deermouse ( Osgoodomys banderanus ). Food and Feeding. Northern Pygmy Mice feed on a variety of grass seeds, leaves, and roots. In semiarid habitats, they eat fruits of prickly pear ( Opuntia lindheimeri, Cactaceae ) and legume seeds (e.g. Prosopisjuliflora, Fabaceae ). Breeding. Northern Pygmy Mice reproduce throughout the year, with peak in late autumn and early spring. Captive individuals are polyestrous, with estrous periods of 7-5 days. Some evidence suggests that they use delayed implantation as a reproductive strategy. Gestation lasts 20-23 days. Litters have 1-5 young (average two). Both parents care for offspring. Lactation lasts 17-24 days. Males reach sexual maturity in 70-80 days after birth and females 60-90 days. Activity patterns. The Northern Pygmy Mouse is nocturnal and crepuscular. Movements, Home range and Social organization. In Texas, densities of Northern Pygmy Mice are 1-84 ind/ha, with lower densities in summer and highest densities in autumn and winter. In the Basin of Mexico, densities are 15-20 ind/ha. Home range are 45-729 m®. They build runways similar to those of species of Microtus , but they are smaller in size. They construct nests of vegetation under trunks, cacti, or herbs. Status and Conservation. Classified as Least Concern on The IUCN Red List. The Northern Pygmy Mouse is a common, has a wide distribution, and faces no known conservation threats. Bibliography. Allen (1903c), Bailey (1905), Blossom & Burt (1942), Ceballos & Galindo (1984), Chavez & Espinosa (2014a), Eshelman & Cameron (1987), Hall (1981), Osgood (1904), Packard (1960), Thomas (1887), Villa (1953).