Sciurus aberti Woodhouse 1853
Creators: name: Wilson, Don E.
name: Thomas E. Lacher, Jr
name: Mittermeier, Russell A.
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Rodentia
Sciuridae
Sciurus
Sciurus aberti

description: 82. Abert’s Squirrel <i>Sciurus aberti</i> <b>French:</b> Ecureuil dAbert / <b>German:</b> Abert-Hérnchen / <b>Spanish:</b> Ardilla de Abert <b>Other common names:</b> Tassel-eared Squirrel; Kaibab Squirrel (kaibabensis) <b>Taxonomy.</b> Sciurus aberti Woodhouse, 1853, “...in the San Francisco Mountains, New Mexico” (= Coconino Co., Arizona, USA]}). Six subspecies are recognized. <b>Subspecies and Distribution.</b> S.a.abertiWoodhouse,1853—SEUtah,SWColorado,CArizona,andWNewMexico(USA). S.a.barberiJ.A.Allen,1904—NSierraMadreOccidentalinWCChihuahua(Mexico). S.a.chuscensisGoldman,1931—NEArizonaandNWNewMexico(USA). S.a.durangiThomas,1893—SSierraMadreOccidentalinSWChihuahuaandWDurango(Mexico). S.a.ferreusTrue,1900—SCWyomingandColorado,NNewMexicoEoftheRioGrande(USA). S. a. kaibabensis Merriam, 1904 — Kaibab Plateau, N of the Grand Canyon (USA). Introduced (probably aberti) into extralimital portions of Arizona, Colorado, New Mexico, and Utah, in the USA. <b>Descriptive notes.</b> Head—body mean 274 mm (males) and 262-3 mm (females), tail mean 208 mm (males) and 221-7 mm (females); weight mean 593-8 g (males) and 618-6 g (females). Abert’s Squirrel has silver-gray to charcoal dorsal pelage, often with medial reddish band. Large ear tufts are conspicuous in winter. Venteris usually white. Tail is slate, frosted with white. Melanism is common, especially in the northern parts of the distribution. Subspecies are allopatric. Nominate aberti has steel-gray back, usually with narrow medial reddish band and lateral black band. Venter is normally white but rarely black, and tail is white below and frosted black above. Individuals in the Hualapai Mountains of western Arizona and the Pinaleno and Santa Catalina mountains of southern Arizona are introduced aberti. Subspecies chuscensis has steel-gray back, with mid-dorsal reddish patch and black lateral band. Body and tail are white ventrally, and tail is black dorsally, with frosting. Subspecies barberi is the largest of the subspecies. Subspecies durangi is the smallest of the subspecies, with tail relatively long compared with body length. Subspecies ferreus is small, with relatively short tail and variable color, including a black phase, a dark brown phase, and a steel-gray dorsum phase. Subspecies kaibabensis is medium-bodied and short-tailed, with black or blackish gray venter and white tail. Chromosome numberis 2n = 40 <b>Habitat.</b> Forests dominated by pines (Pinus, Pinaceae) and are often suggested to be obligates of ponderosa pine (Pinus ponderosa) forests. Mosaic, heterogeneous, and Abert’s Squirrels typically use areas of dense growth in favored unevenly aged forests. Recent evidence suggests that it can persist in more diverse coniferous forests. <b>Food and Feeding.</b> Abert’s Squirrel is herbivorous, with a unique feeding specialization on phloem in winter. Dependence on ponderosa pine, sometimes considered obligatory,is striking. While this dependence is overstated, Abert’s Squirrel is unique in its ability to use phloem as an important food source during periods of winter food shortages, in part due to a lengthened digestive tract. Individuals clip 2-5 cm lengths of small twigs from distal parts of branches,strip the bark, and eat the phloem. Completely stripped clippings are discarded and have been used to estimate densities ofAbert’s Squirrels. Trees with low levels of chemical defenses are preferred when feeding on phloem. They also consume a variety of tree seeds, including those of pine (Pinus), true firs (Abies), Douglas fir (Pseudotsuga menziesii), all Pinaceae, and oaks (Quercus, Fagaceae); they also eat buds, fungi, insects, and bone. Abert’s Squirrel rarely cache seeds; however,it does pilfer from other species that store seeds, such as the North American Red Squirrel (Tamiasciurus hudsonicus) and Fremont’s Squirrel (71. fremont). <b>Breeding.</b> Abert’s Squirrel breeds in spring or early summer when females are receptive for a single day and up to ten males pursue the female. Males possess scrotal testes in winter through summer, after which testes are withdrawn into the abdominalcavity. Females mate with multiple males and solicit copulations from some low-ranking males. Females produce single litters of 2-6 young each year, typically in late spring or early summer, after gestation of ¢.46 days. Dreys and nest cavities are used to rear young. Females may produce a second litter in some localities. Young remain with their mother until natal dispersal, at c.10 weeks of age. Most individuals are able to reproduce at one year old. <b>Activity patterns.</b> Abert’s Squirrels are diurnal and active throughout the year. They have bimodal activity summer with peak activity in the early morning and late afternoon; activity in winter tends to be unimodal and centered on midday heat. <b>Movements, Home range and Social organization.</b> Abert’s Squirrel constructs spherical dreys of pine needles, leaves, and twigs and also den in tree cavities. Individuals live and forage alone, only occasionally interacting with others at concentrated food sources. Communal nesting is uncommon but does occur particularly in winter. Dense growth of twigs known as witch’s brooms caused by parasitic mistletoes are commonly used to anchor and obscure nests. Nests are located in larger and taller trees with canopies connected to adjacent trees and are found in more dense stands of trees, rather than being situated at random in the surrounding area. Individuals change nests regularly and maintain several active nests simultaneously. Foraging occurs in all canopy levels, with significant time spent on the ground. Home ranges are relatively large, often greater than 20 ha, with male ranges larger or equivalent to those of females, perhaps due to mate searching. Abert’s Squirrels rarely vocalize, but when threatened, they utter an alarm call of low frequency and short series of chatters and chucks that has been compared to the bark of a poodle. <b>Status and Conservation.</b> Classified as Least Concern on The IUCN Red List. Population trend of Abert’s Squirrelis stable. It tolerates modest levels of timber harvest and lowintensity ground fires that are common in pine-dominated forests they use. Phloem eating results in a significant reduction of pinecone crops in local areas. This largebodied squirrel is hunted for food and sport. <b>Bibliography.</b> Davis &amp; Brown (1988), Doumas et al. (2015), Edelman &amp; Koprowski (2005, 2006), Lamb et al. (1997), Nash &amp; Seaman (1977), Snyder (1992, 1993), Thorington et al. (2012), Yensen &amp; Valdés-Alarcén (1999).
description: Published as part of <i>Don E. Wilson, Thomas E. Lacher, Jr &amp; Russell A. Mittermeier, 2016, Sciuridae, pp. 648-837 in Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona :Lynx Edicions</i> on pages 744-745, DOI: 10.5281/zenodo.6840226