The Natal mole-rat is a social subterranean rodent that exhibits seasonal reproduction. Nonreproductive females disperse from the natal colony and pair up with unrelated males to establish new colonies. This study set out to determine whether dispersing female Natal mole-rats are induced or spontaneous ovulators. Twelve nonreproductive females removed from natal colonies during breeding season were housed individually. Urine was collected for a period of 5 weeks. Females were subjected to 1 of 3 trials: housed separately without a male, allowed only chemical contact but not physical contact with unvasectomized males, and placed in direct contact with 4 vasectomized males. Urine was collected for a further 5 weeks, and urinary progesterone profiles established. Females housed in direct contact with males exhibited heightened progesterone concentrations and corpora lutea in the ovaries. The act of coitus appears necessary for ovulation to occur in the females despite the fact that males were not capable of fertilization.

Over a 3-year period (1999–2001), we monitored the annual timing of reproduction and hibernation and accompanying changes in body mass of free-living Anatolian ground squirrels (Spermophilus xanthoprymnus) in steppe habitat about 50 km south of Ankara, Turkey. Adult males emerged from hibernation during March, before breeding females. Yearling males emerged with adult males in 2000 but not in 2001. Yearlings of both sexes and adult females were at their lowest body mass of the active season at emergence. Adult males were 139–205% heavier than other age and sex classes when they emerged. Their body mass was near the lowest of the active season at the end of mating season. All adult males had descended testes at emergence, and most yearling males were reproductively active after their 1st hibernation. Females mated shortly after their emergence from hibernation and weaned only 1 litter each year. Females 1st reproduced as yearlings. Parturition occurred in April, and juveniles appeared aboveground from mid- to late May. Thereafter, all age and sex classes were simultaneously active until immergence. In each year, juveniles immerged into hibernation after nonjuveniles. Thus, the annual cycle of Anatolian ground squirrels resembles generally those of most species of hibernating ground squirrels in Europe and North America.

We compared over-winter body temperature (T_b) patterns for more than 6 months in adult (>1 year) black-tailed (Cynomys ludovicianus) and Utah (C. parvidens) prairie dogs from colonies located along gradients of elevation in northern Colorado and southern Utah. In general, black-tailed prairie dogs entered torpor facultatively during winter, whereas Utah prairie dogs hibernated continuously for extended periods. Both black-tailed and Utah prairie dogs displayed significant differences in T_b patterns across elevations, with lower elevation populations entering more shallow and infrequent torpor than prairie dogs at higher elevations. T_b patterns of black-tailed prairie dogs followed 24-h cycles, as most prairie dogs entered into and aroused from torpor between 1100 and 1700 h and bout lengths were clustered around 24-h intervals and multiples thereof. Torpor in Utah prairie dogs did not display the same daily patterns; they entered into and aroused from torpor at all times of the day, and bout lengths were variable. Although black-tailed and Utah prairie dogs are closely related, mechanisms that stimulate and control torpor might differ between them.

The North American red squirrel (Tamiasciurus hudsonicus) typically is regarded as having strong affinities for coniferous forests throughout its geographic range. In the state of Indiana, the red squirrel has expanded its geographic range concurrent with fragmentation of deciduous forests and widespread plantings of conifers. We undertook a radiotelemetry study to assess resource selection and survival of this species in 2 woodlots dominated by deciduous trees in west-central Indiana. Squirrels selected habitats with a high proportion of black walnut (Juglans nigra), avoided other hard mast-producing species, and avoided conifers. Squirrels exhibited overlapping home ranges, consistent with other studies on eastern populations. Individuals whose core areas contained conifers experienced higher survival rates than those individuals whose core areas did not contain conifers. We conclude that the increased safety conferred by conifers, as well as the presence of black walnut in these forests, are likely to contribute strongly to this species' persistence in Indiana.

We report on the natural history of 3 rare and mostly unstudied felids, the clouded leopard (Neofelis nebulosa), Asiatic golden cat (Catopuma temminckii), and marbled cat (Pardofelis marmorata), in Phu Khieo Wildlife Sanctuary, Thailand. From February 1999 to February 2003, 4 clouded leopards (2 males and 2 females), 2 Asiatic golden cats (1 male and 1 female), and 1 female marbled cat were captured, radiocollared, and tracked for 1–17 months. Clouded leopards exhibited annual ranges (95% minimum convex polygon) of 22.9–45.1 km², traveled an average of 1,932 m each day, and were active during 58% of diel activity readings. Asiatic golden cats ranged 32.6–47.7 km², traveled an average of 1,597 m each day, and exhibited an arrhythmic activity pattern of 58% activity. A marbled cat was tracked for 1 month, ranged 5.3 km², and was primarily nocturnal in its habits. Examination of limited data indicated diverse prey use by clouded leopards. Illegal hunting and collecting of aloewood (Aquilaria crassna) threaten the felid community in Phu Khieo Wildlife Sanctuary.

We used data collected from 1979 to 1998 at Powdermill Biological Station in southwestern Pennsylvania to explore the relationship between Cuterebra (botfly) and white-footed mice (Peromyscus leucopus), deer mice (Peromyscus maniculatus), and eastern chipmunks (Tamias striatus). Overall, P. leucopus and P. maniculatus exhibited similar levels of botfly infestation (as measured by prevalence), while T. striatus showed greater prevalence than the mice. Adult P. leucopus and T. striatus exhibited greater prevalence than juveniles, and adult and juvenile P. maniculatus showed similar prevalence levels. Male and female prevalence was similar in each species. Botfly-infested individuals tended to remain significantly longer in the trapping area than noninfested individuals and were more likely to meet our criteria for “residents” than were noninfested individuals. We question the relative impact of botflies on individual survival in these species.

Considerable research supports the tenet that quantity and quality of food limit vertebrate populations. We evaluated predictions that increased availabilities of food and the essential amino acid methionine were related to population limitation of the hispid cotton rat (Sigmodon hispidus). Effects of supplemental food and methionine on density, survival, and reproductive parameters of wild cotton rats were assessed in north-central Oklahoma in 1998–1999. Twelve enclosed groups of 16 adult cotton rats each (8 male, 8 female) were randomly assigned to either no supplementation (control), supplementation with a mixed ration that had methionine at slightly below maintenance levels (0.20%), or a methionine-enhanced mixed ration (1.20%). In general, densities of cotton rats were twice as high and were sustained longer with dietary supplementation, and methionine-supplemented populations maintained the highest densities. Treatment effects on survival depended on time of year, with higher survival in supplemented enclosures in October and November. Per capita recruitment was highest with methionine-enhanced food. Treatment effects on proportions of overall and female cotton rats in reproductive condition depended on sampling date, but males were most reproductively active with methionine supplementation. Methionine supplementation resulted in an earlier and longer reproductive season. Density-dependent and density-independent factors no doubt interplay to determine population dynamics of cotton rats, but our results suggest that methionine plays a role in the population dynamics of wild cotton rats, apparently by enhancing overall density, recruitment, and reproductive activity of males.

Previous experiments designed to estimate daily digestible energy requirements for body-mass maintenance in white-tailed deer (Odocoileus virginianus) were conducted using deer adapted to northern environments. However, animals adapted to warmer, drier environments may have lower metabolic requirements than their temperate conspecifics. We conducted a feeding trial to estimate digestible energy requirements for maintenance of body mass of white-tailed deer in southern Texas and to determine if those requirements vary over time. By restricting dietary levels of digestible energy and measuring deer body mass every 3 days for a 30-day period, we developed a model relating digestible energy intake and change in body mass over time for 11 adult, nongravid females during autumn. Predicted daily digestible energy intake requirements for body-mass maintenance (kJ/kg body mass^0.75) ranged from 820 ± 168 SE at trial initiation to 357 ± 42 at trial completion. Our experiment demonstrated that daily digestible energy maintenance requirements decline during extended periods of energetic restriction and that values previously reported may overestimate the requirements for deer in southern latitudes.

We examined food habits of Tylonycteris pachypus and T. robustula by fecal analysis in 2 counties of Guangxi, South China. The diet of T. robustula included 7 orders of insects: Hymenoptera (62.3% by volume), Diptera (29.6%), Coleoptera (6.0%), Hemiptera (1.5%), and traces of Orthoptera, Trichoptera, and Ephemeroptera. The diet of T. pachypus included all the main orders consumed by T. robustula (53.4%, 29.0%, 13.4%, 2.1%, respectively) and 3 other orders: Homoptera, Blattodea, and Embioptera. No differences were found in diets of males and females of either species. The diet of T. pachypus showed clear seasonal variation from spring to autumn and differences in diet between the different geographical areas studied. There were no differences in the 4 dominant insect orders consumed by both species in Longzhou County, but insects consumed by T. pachypus were characteristically smaller than those eaten by T. robustula, and food-niche breadth (based on prey size) also was smaller than that of T. robustula.

We examined food habits of Brazilian free-tailed bats (Tadarida brasiliensis) at 3 colonies in central Texas over 3 summers. Fecal samples collected from 1,550 bats contained remains of 12 orders and 35 families of insects, documenting the most diverse diet ever reported in insect-eating bats. Daily and seasonal patterns of insect consumption were similar at the 3 sites and closely correlated to patterns of emergence, migration, and availability of adult populations of corn earworms Helicoverpa zea and fall armyworms Spodoptera frugiperda, both species of noctuid moths and major crop pests. The percentage of feces volume comprised by moth remains increased from 14.8% ± 2.1 SE (range: 6.3–43.7%) to 43.0% ± 7.1 (range: 1.7–73.5%) in samples collected at midnight versus dawn on days when large influxes of migratory moths arrived in Texas in early morning, following their massive emergence from northern Mexico. Daily patterns diminished later in the season, after moth populations became established in local crops and were available in large numbers throughout night. Moth consumption decreased in both evening and dawn feeding periods when crops senesced and moth populations declined. These and other data suggest that crop pests comprise a substantial portion of the bats' diet and that bats provide valuable natural pest control services.

Bat conservation is hindered by a lack of geographic-specific knowledge of characteristics of roost sites used by reproductive females. We examined roost selection by reproductive female Myotis evotis (long-eared myotis) in the Channeled Scablands of northeastern Washington. We used radiotelemetry to locate 35 roosts of reproductive female Myotis evotis. Habitat variables were measured for each roost itself and at a 0.1-ha microplot and 78-ha macroplot surrounding each roost. We measured habitat variables at random 0.1-ha microplots in the vicinity of each roost and at general random 0.1-ha microplots and 78-ha macroplots. Thirty-four roosts were found in crevices in small basalt rock formations. All radiomarked bats switched roosts at least once and roost switching apparently involved the entire colony. The average number of switches was 3.3 with an average of 2 days between roost switches. The distance traveled between day roosts averaged 148.9 m. Compared to random plots, roosts were in more open, rocky habitats, closer to edge of forest stands, and relatively distant from sources of permanent water.

Most recent research on the roosting habits of temperate, forest-living bats has focused on species that use enclosed cavities, but less has been done to address roosting by foliage-living species, which are assumed to have more flexible roost requirements. Numerous studies have suggested that bats select roosts on the basis of microclimate, yet few have tested this hypothesis empirically and none have addressed the use of foliage roosts in this context. We used radiotelemetry to locate roost sites of reproductive female hoary bats (Lasiurus cinereus) then compared a variety of physical features of these trees with randomly selected nonroost trees. We also recorded ambient temperature and wind speed at roost and nonroost sites to test the hypothesis that physical features associated with foliage roosts provide energetic benefits. Hoary bats selected roost sites on the southeast side of mature white spruce trees (Picea glauca; X̄ orientation 158.6 ± 6.3° SSE). Roost trees were more likely than random trees to be the same height as the surrounding forest canopy; had less canopy cover facing out from the tree in the direction of the roost branch; and had lower forest density on their southeast side. Wind speed was significantly lower at roosts sites compared with opposite sides of the same trees, presumably due to increased protection from prevailing west winds. Incorporating an estimate of convective cooling due to wind, we predicted daily thermal energy expenditure for normothermic bats and found that selected roost sites provided statistically significant energy savings (up to 1.60 ± 0.99 kJ/day) relative to the predicted expenditures if bats had roosted on the opposite sides of trees. Our results provide direct evidence that hoary bats select forest roosts on the basis of microclimate and suggest that roost requirements of foliage-roosting species may be more specific than has been previously assumed.

We tested the 5% rule for the ratio of radiotransmitter mass to body mass by applying radiotransmitters and passive integrated transponders (PIT tags) or PIT tags alone to adult, female big brown bats (Eptesicus fuscus) roosting in buildings in Fort Collins, Colorado. We used records from PIT readers at roosts to compute apparent annual survival of both groups from 2001 to 2003 and found them to be similar. All bats examined 1 year after radiotagging were reproductively active and had body masses similar to bats not radiotagged. Big brown bats do not appear to suffer from major long-term effects of carrying transmitters within the 5% rule.

Social flexibility, that is, the expression of different types of social systems within one species, has been reported in several mammalian taxa, including rodents. However, sociality in rodents has been studied mostly in captivity and the results are often regarded as laboratory artifacts. We present field data for 2 populations of the striped mouse (Rhabdomys pumilio), a diurnal muroid rodent from southern Africa. The 2 populations inhabit different environments and demonstrate differences in social organization. R. pumilio in the arid succulent karoo lives in social groups, comprising multiple adults of both sexes that share 1 nest and the same territory. Striped mice in the moist grasslands of South Africa are solitary. Females inhabit exclusive territories and territories of males overlap those of several females; association between the sexes appears to be restricted to mating. Home ranges of females in the grasslands were 6 times larger and home ranges of males were 10 times larger than their counterparts in the succulent karoo. Onset of reproductive activity occurred earlier and at a significantly lighter body weight in grasslands. In the succulent karoo, sexually mature offspring remain in their natal group without reproducing. We suggest that group living in the succulent karoo is in response to habitat saturation and the benefits of philopatry, whereas living alone in the grasslands may be a response to limiting resources, such as food.

Loss of cached foods is a constant threat to animals that hoard food, and pilfering plays an important role in the evolution of hoarding strategies. Although pilfering is known to affect the behavior of scatter hoarders, pilfering has been assumed to be less important for larder-hoarding animals. In this study, I used a mark-recapture study of cached Norway spruce (Picea abies) cones to quantify pilfering rates in larder-hoarding red squirrels (Tamiasciurus hudsonicus). Red squirrels stole 26% of the cones that they ate and lost 25% of the cones cached in their middens. Most squirrels stole cones (97%) and lost cones to stealing (92%). However, individual squirrels stole 1–100% of the cones that they ate and lost 1–84% of the cones cached in their middens. Numbers of cones gained by and lost to stealing were not related to the age or sex of individual squirrels or the distances between or numbers of cones cached in individual territories. Squirrels with small middens, however, ultimately gained cones, and those with large middens lost cones. Because food is frequently a limiting resource for red squirrels, these changes in food abundance may directly affect the fitness of individual squirrels. Thus, pilfering likely plays an important role in shaping the hoarding and defensive behaviors of larder-hoarding animals.

We describe distinctive characteristics of the magnum-trapezoid and other carpals found associated with an antler of the extinct genus Bretzia from southwestern Idaho from late Pliocene (Blancan V) Glenns Ferry Formation deposits (2.4 × 10⁶ years ago) of the Birch Creek drainage. This antler and elements of the foreleg represent a midpoint in the known evolutionary history of the genus. The oldest known antlers from a species of Bretzia are from the Pliocene Ringold sediments (4.2 × 10⁶ years ago) of Washington; and the most recent antlers are from South Dakota and Nebraska sediments of Rancholabrean–Holocene times (10,000–15,000 years ago). Carpal elements of the foreleg of Bretzia have a unique feature of the magnum-trapezoid not found in other extant New World cervids studied.

Young arctic ungulates must grow quickly to use forages available during brief summers. We measured growth and organ maturation in Rangifer tarandus (reindeer, caribou) and Ovibos moschatus (muskoxen) at 3 stages: the neonatal period (1–30 days), during transition from milk to plants (30–60 days), and at maturity. Although reindeer provided greater maternal investment than muskoxen in utero (6.9% compared with 4.8% maternal mass), both species grew at similar rates (0.002 compared with 0.005 day⁻¹). High thyroid secretion and large hepatic lipid reserves in neonates indicated high rates of energy metabolism for thermogenesis and use of nutrients sequestered in utero. Mass gains during the neonatal period were associated with large gastric abomasa that would allow young ungulates to digest milk soon after birth. Body growth continued during transition to forage (60 days of age), which was accompanied by expansion of rumen, small intestine, and colon. Growth and organ maturation of arctic ungulates, therefore, emphasizes maternal investment in utero and the duration of growth, with little variation in growth rate during both neonatal and transitional phases.

This paper presents evidence of the presence and subsequent loss of postnatal skin in an ecdysis-like process in southern right whales, Eubalaena australis. Individuals whose skin was noticeably uneven, spongy, broken, and often light gray in color formed ≥20% of right whale neonates seen on the South African coast on any day up to and including the 1st week of September. Thereafter ≥85% of calves were of the normal, smooth-skinned appearance. The 50% transition point between the 2 forms occurred on 31 August (95% CI 1.1 days), or about a week after birth. Histological analysis of skin from stranded neonates showed a definite cleavage plane in the midepidermis, the mechanical integrity of which was further compromised by low concentrations of desmosomes and intracellular filaments. We propose that focal edema develops between the cells and forms the cleavage plane, which eventually leads to separation of the outer epidermal cell layer (cf. spongiosis in humans). The movement from the intrauterine to the oceanic milieu, and the osmoregulatory consequences thereof, may be a catalytic factor for this process to occur. This ecdysis may have important consequences for the cyamid fauna of neonatal right whales.

Balaenopteridae actively feed by engulfment. They swim rapidly at their prey (40–50 km/h), with their mouth open and their lower jaw pulled wide open at a 90° angle. Their mouth and ventral pouch engulf up to 60 m³ of water, then the mouth closes and food is swallowed after the expulsion of water through the baleen. These highly specialized feeding mechanisms are associated with a developed ascending process of the maxilla and a hooklike and outwardly bent coronoid process of the dentary. These features participate in the strengthening of the architecture of the skull and jaw. Although all fossil baleen mysticetes bear a developed coronoid process, only 6 taxa (Piscobalaena nana, Cetotherium rathkei, Herpetocetus sendaicus, Metopocetus durinasus, Mixocetus elysius, and Nannocetus eremus) have a posteromedially expanded ascending process of the maxilla. Feeding strategies and mechanisms of each extant family of baleen whales are compared and correlated with the associated skull and dentary features. This correlation suggests a preliminary phylogeny of the mysticetes and a new definition of the Cetotheriidae sensu stricto (Piscobalaena nana, Cetotherium rathkei, Herpetocetus sendaicus, Metopocetus durinasus, Mixocetus elysius, and Nannocetus eremus).

Phylogenetic relationships among 51 individuals of South American mouse opossums (Thylamys) were examined by using nucleotide sequence data from the mitochondrial cytochrome-b gene. Parsimony, likelihood, Bayesian, and genetic distance analyses revealed several distinct clades. T. macrurus (subtropical forest of eastern Paraguay) was strongly differentiated from all other species. T. venustus (Yungas forest on eastern slopes of the Andes of Bolivia and Argentina) separated into 2 strongly supported clades, providing support for recognition of 2 species, T. venustus and T. cinderella, but not supporting the distinctness of T. sponsorius. T. tatei (central coast of Peru) was sufficiently different from T. elegans (Matorral of Chile) to support species recognition. The dichotomy between northern (Chile and Bolivia) and southern (Argentina) clades of T. pallidior suggested the presence of 2 subspecies. High levels of DNA sequence variation indicated substantial genetic differentiation among and between clades, and combined with the phylogenetic analyses provide support for the systematic conclusions. Estimates of times since divergence suggest a radiation beginning in the Miocene and continuing through the Pliocene and correspond with changes in climate, vegetation, and geology that occurred during these times.

Female pseudohermaphroditism is characterized by gonads consistent with chromosomal sex combined with ambiguous, masculinized external genitalia. Recognized in many mammals, this condition results from fetal exposure to androgens that can be embryonic, maternal, or environmental in origin. Female pseudohermaphrodite black and brown bears (Ursus americanus and U. arctos) from Alberta, Canada, and polar bears (U. maritimus) from Svalbard, Norway, have been identified. Recent population surveys in Nunavut, Canada, led to the discovery of 11 additional female pseudohermaphrodite polar bears. Each bear was screened for the presence of sex-determining region-Y (Sry) and amelogenin-Y (AMELY) genes as indicators of Y-chromosome DNA. One bear possessed both genes, implying that trisomy or a chromosomal rearrangement may account for her virilized phenotype. Preliminary data suggested that Sry was also present in the other 10 bears; further testing disproved that result, revealed an important source of error when using polymerase chain reaction (PCR) to screen for the Sry gene, and led to the development of new amelogenin primers that provide superior sex information for bears. Ultimately, these extensive screens also supported the conclusion that 10 of 11 morphologically abnormal individuals may possess no genuine male-specific DNA. Therefore, nongenetic mechanisms such as maternal tumors, freemartinism, or endocrinological effects of environmental contaminants may also influence the development of the female pseudohermaphrodite phenotype in Nunavut polar bears.

Subterranean tuco-tucos (genus Ctenomys) are a speciose group of South American hystricognath rodents, often taken as an example of explosive speciation. The 4th intron of the rhodopsin gene (567 bp) and partial sequence of the 2nd intron of the vimentin gene (403 bp) were used to assess phylogenetic relationships among 20 species of Ctenomys and 3 octodontid species. Some of the main groups of Ctenomys species previously reported in the literature (e.g., the “boliviensis” group) are confirmed, as is the lack of resolution of basal nodes. This star-like pattern of diversification of tuco-tucos was recovered with both the new nuclear dataset and an expanded mitochondrial dataset, providing further evidence that Ctenomys underwent a phase of rapid diversification early in its history.

Genetic diversity within a population of the southern plains woodrat was examined using DNA sequences (967 base pairs [bp]) obtained from the control or d-loop region of the mitochondrial genome. One hundred fourteen individuals from 10 collection sites were assigned to 42 haplotypes. Haplotype diversity values were moderate to high (0.974 overall and ranged from 0.524 to 0.964 across collecting sites), whereas nucleotide diversity values were low (0.008 overall and ranged from 0.001 to 0.010 across sites), indicating that this population possesses a high number of closely related haplotypes. Seventy-nine percent of the genetic variability was partitioned within groups that corresponded to the collecting sites. In addition, 13 samples from Texas, New Mexico, and Mexico were included as references for evaluating the evolutionary history of haplotypes. Nested clade analysis revealed that restricted gene flow with isolation by distance in conjunction with contiguous range expansion was responsible for the observed pattern of genetic diversity. A test of neutrality supported the diagnosis of restricted gene flow, but failed to support contiguous range expansion due solely to population growth. Examination of the spatial distribution of the haplotypes indicated that most haplotypes were restricted to a single collecting site; however, a small number of haplotypes were found at 2 or more sites. A phylogenetic analysis indicated that some haplotypes (28.6%) were restricted to the study area whereas the remaining haplotypes occupied a broader geographic region.

Phylogeographic relationships were evaluated at the intraspecific level using nucleotide sequence data from the mitochondrial cytochrome b gene of representative specimens of “colilargo” (Oligoryzomys longicaudatus) from 31 localities, along its distributional range over a large part of the western Andes and southern Argentina. Based on approximately 1,000 base pairs (bp), we recognized a single species on both the Chilean and the Argentinean side as far as at least latitude 51°S, rejecting the subspecific distinctiveness of longicaudatus and philippi. We thus placed the latter in full synonymy with O. longicaudatus as earlier studies proposed, and enlarged its range as far as Torres del Paine, about 51°S. The occurrence of subspecies in this range is doubtful given the low sequence divergence values and the absence of significant associations between haplotypes and their geography. Additionally, we hypothesized that the entrance of this species into the Chilean side of the Andes mountains occurred through the Patagonian forests of southern Argentina, with further dispersal to the north from the south.

Taxonomic relationships among red tree voles (Phenacomys longicaudus longicaudus, P. l. silvicola), the Sonoma tree vole (P. pomo), the white-footed vole (P. albipes), and the heather vole (P. intermedius) were examined using 664 base pairs of the mitochondrial cytochrome b gene. Results indicate specific differences among red tree voles, Sonoma tree voles, white-footed voles, and heather voles, but no clear difference between the 2 Oregon subspecies of red tree voles (P. l. longicaudus and P. l. silvicola). Our data further indicated a close relationship between tree voles and albipes, validating inclusion of albipes in the subgenus Arborimus. These 3 congeners shared a closer relationship to P. intermedius than to other arvicolids. A moderate association between pomo and albipes was indicated by maximum parsimony and neighbor-joining phylogenetic analyses. Molecular clock estimates suggest a Pleistocene radiation of the Arborimus clade, which is concordant with pulses of diversification observed in other murid rodents. The generic rank of Arborimus is subject to interpretation of data.