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Behavior and activity budgets of Sonoran pronghorns (Antilocapra americana sonoriensis).

Knowledge of basic life history is a prerequisite for recovery and effective management of endangered species (Scott et al., 1996). Activity budgets help to increase understanding of constraints a species faces and help wildlife managers determine management strategies (Dietz, 2004). Additionally, baseline behavioral data can be a useful assessment tool for reintroduction efforts of endangered species (Berger et al., 1999), or effects of perturbation on behavior (Clemmons and Buchholz, 1997). A lack of behavioral information was a factor that led to failure of reintroduction efforts for a population of pronghorns (Antilocapra americana) in California (Goldsmith, 1992).

Little is known about behavior and activity budgets of the Sonoran pronghorn (A. a. sonoriensis), despite being listed as endangered since 1967 (United States Fish and Wildlife Service, 1967). Behavioral data are difficult to obtain because the population is <100 individuals (Krausman et al., 2005b) and is distributed over 600,000 ha (Hervert et al., 2000), mostly in wilderness or on an active military firing range where access is restricted (Krausman et al., 2005a).

Many studies have documented activity patterns and behavior of other subspecies of pronghorns (Einarsen, 1948; Buechner, 1950; Byers, 1997; Krausman et al., 2004). To assume, however, that results of these studies apply to Sonoran pronghorns is inappropriate due to regional differences in factors that affect activity patterns, e.g., temperature (Leopold and Krausman, 1987; Tieleman and Williams, 2002), availability of forage (Tieleman and Williams, 2002), or risk of predation (Pettersson et al., 2001). Thus, drawing inferences from other studies might not provide the necessary information about how Sonoran pronghorns respond to conditions of the Sonoran Desert. If behavior of Sonoran pronghorns does not differ substantially from other subspecies that live in similar environments (i.e., A. a. mexicana, A. a. penninsularis), then those subspecies could be used as surrogates to answer behavioral questions that are not possible to address in wild Sonoran pronghorns.

Only one published study exists on activity budgets of Sonoran pronghorns, but that research established only annual activity budgets (Krausman et al., 2004) due to difficulties of collecting behavioral data in the wild. However, in 2003, a semi-captive breeding facility for Sonoran pronghorns was built as part of recovery efforts initiated for the subspecies (Wilson et al., 2006). Establishment of this facility, within habitat of the Sonoran pronghorn, provided a unique opportunity to study behavior of the subspecies in semi-natural conditions.

Our objectives were to compile seasonal diurnal activity budgets for adult females and to determine foraging and maternal behavior. We also collected information on use of shade and frequency of drinking to evaluate how Sonoran pronghorns cope with high temperatures and to inform the ongoing debate about the necessity of water for their survival (Morgart et al., 2005). Finally, we evaluated whether behavior of the Sonoran pronghorn differed from that documented for other desert-dwelling subspecies.

MATERIALS AND METHODS--Study Area--The semi-captive breeding enclosure for Sonoran pronghorns is located in the Sonoran Desert on Cabeza Prieta National Wildlife Refuge, Pima Co., Arizona, at an elevation of 460 m. The enclosure encompasses 260 ha, but during our study, pronghorns could only use 130 ha due to internal fencing and captive management. Managers of the enclosure maintained two water sources for pronghorns during the study. Eight forage-enhancement plots (i.e., 8,000-[m.sup.2] areas watered periodically to increase quantity and quality of forage; Hervert et al., 2001) also were established in the enclosure. An electric fence surrounded the enclosure to restrict predators, although we observed one bobcat (Lynx rufas) and two coyotes (Canis latrans) within the enclosure during the study. A complete description of the enclosure is provided in Wilson (2006).

We divided the year into 4 seasons based on temperature and rainfall in the Sonoran Desert: winter (January-March), spring (April-June), summer (July-September), and autumn (October-December). Rainfall during our study (114, 2, 33, and 4 mm, in winter, spring, summer, and autumn, respectively; http:// was lower than long-term averages (1914-2007) for Ajo, Pima Co., Arizona (18, 4, 33, and 16 mm, in winter, spring, summer, and autumn, respectively; Western Regional Climate Center, pl?az0080), except during winter when rainfall was >6 times the long-term average. Average daily high temperatures during this study (20, 34, 39, and 28[degrees]C, in winter, spring, summer, and autumn, respectively; did not differ substantially from long-term averages for Ajo (21, 33, 38, and 26[degrees]C in winter, spring, summer, and autumn, respectively; Western Regional Climate Center, pl?az0080).

Population Studied--Biologists from the Arizona Game and Fish Department and the United States Fish and Wildlife Service placed Sonoran pronghorns into the enclosure as part of recovery efforts. One adult female and one young female from Mexico were captured and released into the enclosure in January 2004; one adult male and four adult females were captured in Arizona during April and December 2004, respectively. Enclosure managers fitted each pronghorn with a uniquely colored radiocollar. During February-March 2005, all females gave birth (i.e., four twins, two singletons; Wilson et al., 2008b). In mid-July 2005, however, four young died of unknown causes. One adult female died in mid-November 2005 of unknown causes. Because this female died close to the end of the study, we did not censor her data for autumn. We acknowledge the small sample for our study (n = 6), but the captive population represented ca. 10% of the free-ranging population of Sonoran pronghorns in the United States at the time of study (ca. 50 as of December 2004; Krausman et al., 2005a).

Behavioral Sampling--We observed Sonoran pronghorns with the aid of a spotting scope (Swarovski AT-80 20-60x, Bushnell 15-45x) from Packrat Hill (32[degrees]22'N, 113[degrees]00'W) during 23 January-2 December 2005. Observational distances were 240-2,200 m.

We recorded behaviors (Table 1) of all visible pronghorns by hand or on a handheld computer (Tungsten E2, palmOne, Inc., Milpitas, California) with instantaneous sampling (Altmann, 1974) at 2-min intervals. Because pronghorns had individually colored radio-collars, we obtained repeated measures of behavior of individuals throughout the study. If we saw an individual foraging, we attempted to determine class of forage consumed (i.e., corb-grass, shrub, tree, cactus), because we could not determine species consumed due to long-distance observations (Wallmo et al., 1973). We could not distinguish grasses from forbs so we combined them, although corbs likely constituted the majority of these observations because pronghorns rarely consume grasses (Hervert et al., 2000). We only recorded class of forage when we knew the class an animal consumed (e.g., pronghorn pulling bean pods off palo verde Cercidium). When we observed pronghorns bedding or standing, we noted rumination. When they bedded, we noted whether they bedded in shade or sun.

We allocated an equal number of days to morning and afternoon observations during each season. We applied this sampling scheme to observations collected during winter and autumn and to portions of spring and summer. In late spring and early summer, we could not obtain behavioral observations during the middle of the day because pronghorns became inactive or used heavily vegetated washes. Therefore, during 31 May-2 August, we allocated daily sampling effort from sunrise until we no longer observed pronghorns (ca. 0900-1100 h). We returned in late afternoon when they became active, and we recorded behaviors until sunset. When we could collect observations through late morning, we would not conduct observations during the afternoon. Instead, we allocated sampling effort on the following day from early afternoon until sunset. We did not obtain observations on days with a large amount of disturbance at the enclosure (e.g., a backhoe creating a firebreak around the enclosure). Our sampling strategy provided a sufficient number of observations during each period and season to obtain precise estimates as Wilson et al. (2008a) determined that precise estimates of activity-budget parameters can be obtained with <250 observations/individual.

Activity Budget--We used times of sunrise and sunset from Ajo (United States Naval Observatory, http://aa. and divided days into 6 periods: sunrise, 1 h before and after sunrise; early morning, 1 h after sunrise to 0930 h; late morning, 0932-1200 h; early afternoon, 1202-1430 h; late afternoon, 1432 h to 1 h before sunset; and sunset, 1 h before and after sunset. We observed Sonoran pronghorns 4-5 days/week during 1 of 2 times of day: first light through late morning (morning) or early afternoon to last light (afternoon). We calculated seasonal activity budgets similar to Moncorps et al. (1997) by calculating activity budgets for each adult female during each diurnal period (within a given season). This allows for estimates of activity budget to not be biased by periods with greater numbers of observations. We then averaged activity budgets across the 6 periods for each female. For example, if we observed a female foraging 20, 15, 2, 7, 14, and 28% of observations during sunrise, early morning, late morning, early afternoon, late afternoon, and sunset, respectively, during winter, then we calculated that particular female as foraging 14.3% (i.e., the six percentages were summed, then divided by six) of the time during winter. To create annual activity budgets, we averaged the 4 seasonal values for each female. To determine if activity budgets varied by season, period of day, or if diurnal allocation of time to each behavior varied by season (i.e., season by period interaction), we combined observations within each season into 1 of the 6 diurnal periods for each female. This method also helped us control for potential error in using percentage data to compile activity budgets in an area with variable day length among seasons (Hill et al., 2004).

Statistical Analysis--We used a two-factor repeated-measures analysis of variance (ANOVA) with season and period as repeated factors (Cody and Smith, 1997) for analysis of activity budgets. For all other tests, we used repeated-measures ANOVA (Cody and Smith, 1997) with Bonferroni corrected ([alpha] = 0.05/6) paired t-tests for multiple comparisons (Zar, 1999). For repeated-measures tests, we tested that the sphericity assumption was met. If the assumption was not met, we used the Huynh-Feldt Epsilon adjusted P-value (SAS Institute, Inc., 2003). We transformed (arcsine-square root) all data to meet normality assumptions (Zar, 1999) and performed residual diagnostics to check that data met normality and variance assumptions (Neter et al., 1996). We performed all statistical analyses with SAS (SAS Institute, Inc., 2003). By using a repeated-measures design, we increased our power to detect differences in activity budgets if they existed and, therefore, helped to compensate for the small samples. The University of Arizona Institutional Animal Care and Use Committee approved this research (protocol 06-016).

RESULTS--Activity Budgets-We recorded behavior of Sonoran pronghorns on 148 days (35, 44, 42, and 27 for winter, spring, summer, and autumn, respectively). We recorded 49,035 behavioral observations with an average of 8,173 [+ or -] 250 (SE) observations/individual. We observed individual pronghorns during 34.7 [+ or -] 0.7% of observation bouts. We observed [greater than or equal to] 1 pronghorn during 76.6% of observation bouts. Annually, adult females spent most time foraging (46.3 [+ or -] 1.6%), followed by standing (21.0 [+ or -] 1.0%), bedding (16.4 [+ or -] 0.9%), and traveling (14.1 [+ or -] 0.8%).

Percentage of time that adult females foraged ([F.sub.3,15] = 35.49, P< 0.001), bedded ([F.sub.3,15] = 6.16, P = 0.006), and stood ([F.sub.3,15] = 37.21, P < 0.001) differed seasonally, but traveling did not ([F.sub.3,15] = 1.71, P= 0.207; Table 2). Pronghorns spent more time foraging during autumn than other seasons, which had similar levels. They spent a similar percentage of time bedded in spring, summer, and autumn, but tended to bed more during winter. They stood a similar percentage of time during spring and summer, with a small decrease in winter, and a marked decrease in autumn (Table 2).

Diurnal patterns of behavior differed across seasons. Percentage of time adult females foraged ([F.sub.15, 75] = 4.54, P < 0.001), bedded ([F.sub.15, 75] = 5.65, P < 0.001), stood ([F.sub.15,75] = 2.50, P = 0.005), and traveled (F15, 75 = 10.58, P < 0.001) exhibited a season by period interaction (Fig. 1). Pronghorns shifted from relatively crepuscular foraging patterns in winter through summer, to a more diurnal pattern in autumn (Fig. 1). Pronghorns also shifted bedding patterns in spring and summer to peak during mid-day, whereas in winter and autumn, bedding primarily occurred during early morning (Fig. 1). The time of greatest seasonal difference in traveling was early afternoon, with higher amounts of travel during winter and autumn than spring and summer (Fig. 1). Finally, they showed similar patterns of standing during summer and autumn, with peaks in late morning and late afternoon, whereas during spring, pronghorns stood most frequently during mid-day (Fig. 1). Standing did not vary diurnally in winter (Fig. 1).

Foraging Behavior--Diets differed by season (Table 3). Forbs-grass ([F.sub.3, 15] = 52.83, P < 0.001), shrubs ([F.sub.3, 15] = 17.96, P < 0.001), and trees ([F.sub.3, 15] = 63.77, P < 0.001) differed in use by season, but not cactus ([F.sub.3, 15] = 0.94, P = 0.512; Table 3). Use of forbs-grass decreased from a high in winter to lows in summer and autumn (Table 3). Use of shrubs was greatest in summer and least in spring, with intermediate levels in winter and autumn (Table 3). Pronghorns foraged on trees most frequently during spring and autumn (Table 3), but browsed on different parts of trees; fruits, e.g., mesquite (Prosopis) and palo verde beans were consumed most during spring and foliage was consumed more frequently during autumn.


Percentage of time pronghorns ruminated while inactive (i.e., bedded plus standing) varied seasonally ([F.sub.3, 15] = 10.10, P = 0.001), with rumination occurring more frequently during autumn than in other seasons. They ruminated 48.4[+ or -]4.3,49.9[+ or -]6.1,44.3[+ or -]5.2, and 71.4[+ or -] 6.4% of time while inactive during winter, spring, summer, and autumn, respectively. However, the actual percentage of time pronghorns ruminated (i.e., proportion of time ruminating while inactive times proportion of time inactive times 100) each season (19.5 [+ or -] 1.6, 19.5 [+ or -] 2.6, 18.4 [+ or -] 2.2, and 20.8 [+ or -] 2.5% of time, for winter, spring, summer and autumn, respectively) did not differ ([F.sub.3, 15] = 0.40, P = 0.750).

Shade Seeking--Percentage of time pronghorns bedded in shade varied seasonally (F3,15 = 13.93, P = 0.008). They bedded in shade 6.4 [+ or -] 4.1, 78.8 6.9, 99.4 [+ or -] 5.5, and 27.2 [+ or -] 5.5% of time during winter, spring, summer, and autumn, respectively. Bedding in shade occurred more frequently during spring and summer than in winter and autumn.

Drinking Activity--We first observed pronghorns drinking from water troughs on 12 April. All pronghorns drank from waterers through the end of the study. Excluding winter, percentage of time spent drinking did not differ among seasons ([F.sub.2, 10] = 1.46, P = 0.280; Table 2).

Maternal Behavior--Females nursed their young 14.3 [+ or -] 1.4 weeks with a peak from birth through 4 weeks of age, after which nursing declined until it became negligible after 12 weeks of age (Fig. 2). Females groomed their young 3.8 [+ or -] 0.6 weeks post parturition.

DISCUSSION--Management and recovery of endangered species are difficult tasks because they rely on obtaining adequate information on life history (Scott et al., 1996) and these data often are difficult to obtain. The semi-captive breeding enclosure provided a reasonable approach to study behavior, and under semi-natural conditions, data on behavior still represent that of free-ranging populations (Zinc and Krausman, 2000).

Sonoran pronghorns in this study lived in a semi-captive facility with minimal human interaction or disturbance. Also, they had been in captivity <1 year at the beginning of the study. Thus, conditions were ideal for obtaining observations representative of free-ranging individuals.

Annual activity budgets for Sonoran pronghorns correspond to the annual activity budget of an adjacent free-ranging population of Mexican pronghorns (A. a. mexicana) in Arizona, differing only in percentage of time traveling (Krausman et al., 2004), which, given captive conditions, would be expected. In the same study, Krausman et al. (2004) observed free-ranging Sonoran pronghorns foraging less and traveling more than observed in our study. Contradictory results for Sonoran pronghorns between our study and those of Krausman et al. (2004) might be due to greater observational distances in their study (i.e., 1-10 km), different sampling techniques, and differences in range conditions (i.e., quality and quantity of forage) between the two study areas and periods. Whereas these differences might be the result of our study population being in captivity, discrepancies are more likely related to sampling differences between studies. Observations of Sonoran pronghorns by Krausman et al. (2004) were opportunistic, whereas their observations of Mexican pronghorns were systematic and more similar to our current study.

Annual activity budgets of other populations also are similar to our results. In Montana, females (A. a. americana) foraged a similar percentage of time (ca. 46%), but bedded less (ca. 28%) than in our study (Byers, 1997). Activity budgets in West Texas (Buechner, 1950), however, differed from our results with pronghorns foraging a greater percentage of time (ca. 70%) and traveling and standing less (ca. 7 and 2%, respectively). Differing results may be due to slightly different definitions of what constitutes foraging (Buechner, 1950:301). Interestingly, pronghorns in Montana and Texas foraged a similar percentage of time during the season of lowest availability of forage as did pronghorns in our study (Buechner, 1950; Byers, 1997). Thus, overall seasonal activity budgets are similar across subspecies when periods of lowest availability of forage are considered.


While seasonal activity patterns differed little between populations, it is important to consider how Sonoran pronghorns allocated time diurnally within a season. Sonoran pronghorns faced different environmental constraints (e.g., thermal and forage conditions) during this study and responded by altering their allocation of time to different behaviors. Temperature during spring and summer constrained activity of Sonoran pronghorns. Animals alter diurnal activity to adjust for temperature (Arnold, 1981), but compensate for reduction in mid-day activity with increased crepuscular or nocturnal activity (Roberts and Dunbar, 1991; Hayes and Krausman, 1993). Sonoran pronghorns decreased percentage of time active (i.e., foraging and traveling) during the hottest part of the day by switching to a more crepuscular activity pattern, which can significantly reduce water loss (Soholt et al., 1977). Other studies on desert-dwelling ungulates detected similar increases in crepuscular activity patterns during the hottest parts of the year Uarman and Jarman, 1973; Leopold and Krausman, 1987; Alderman et al., 1989; Krausman et al., 1999).

Use of shade by Sonoran pronghorns increased during spring and summer, and a similar pattern was documented in mule deer (Odocoileus hemionus; Tull et al., 2001). On cooler summer days, pronghorns remained active longer into the morning than on hotter days. Similarly, Leopold and Krausman (1987) observed that desert mule deer (O. h. eremicus) ceased activity when ambient temperature was >30[degrees]C. Arabian oryx (Onyx leucaryx) sought shade when ambient temperatures were >35[degrees]C, and percentage of time spent inactive in the shade was positively correlated with ambient temperature (Ostrowski et al., 2003). Minimizing time spent in the open during the hottest parts of the day in spring and summer significantly reduces water loss and thermal load (Finch, 1972) and is common among desert-dwelling ungulates (Jarman and Jarman, 1973; Roberts and Dunbar, 1991; Krausman et al., 1999). On the western section of Cabeza Prieta National Wildlife Refuge during summer, shaded areas are 3.3[degrees]C cooler than in sun (Cain et al., 2008).

During autumn, availability of forage likely constrained activity of pronghorns. Although we did not measure availability of forage due to restricted access to the enclosure, we observed visible browse lines and denuded vegetation in the enclosure, indicating limited forage. Forage conditions in the enclosure decreased throughout the year as rainfall was lower than average in all seasons but winter. Increased time spent foraging suggests that during autumn, pronghorns had difficulty finding sufficient forage (Jarman and Jarman, 1973; Arnold, 1981; Hanley, 1982; Forchhammer, 1995; Moncorps et al., 1997). Constraint of activity due to availability of forage is further supported by initiation of supplemental feeding of alfalfa hay on 2 December after we observed [greater than ore equal to] 2 adult females in poor body condition (i.e., visible ribs, no rump fat, pelvis visible through skin).

Sonoran pronghorns live in a harsh desert environment with periods of extreme drought (Bright and Hervert, 2005). In 2002, the most extreme drought on record occurred and even the most drought-resistant plants (e.g., creosote-bush Lamrea tridentata) suffered increased mortality U. Morgart, personal observation). As a result, there was an 80% decrease in the population of Sonoran pronghorns in the United States (Bright and Hervert, 2003). Our data allow some extrapolation to how free-ranging Sonoran pronghorns might respond to decreasing forage during a drought. Knowing how Sonoran pronghorns might respond to drought conditions provides managers with information to implement management strategies that help decrease risk of extirpation during future droughts. Specifically, managers can use this information to help determine how many, and how large forage-enhancement plots need to be to meet foraging demands of Sonoran pronghorns during periods when most of their forage is desiccated.

Until recently, many believed that Sonoran pronghorns obtained water through means other than drinking water (Morgart et al., 2005). Morgart et al. (2005) documented many instances of free-ranging Sonoran pronghorns drinking at human-made water developments. We also observed pronghorns regularly drinking from two water sources in the enclosure during April-December. The earliest Morgart et al. (2005) recorded Sonoran pronghorns drinking was 11 April, whereas we first observed captive pronghorns drinking on 12 April. Drinking by desert-dwelling ungulates is related to water content of forage and drinking ceases when water is >70% (Beale and Smith, 1970; Jarman, 1973). Sonoran pronghorns in this study likely did not drink water until April because forbs (i.e., the major food item in their diet during winter; Table 3) have high water content (Beale and Smith, 1970). Only after their diet shifted to browse was drinking necessary to meet water requirements. Sonoran pronghorns in this study might have drunk before 12 April, on days that we did not collect observations. That we could have continuously missed them drinking for >3 months prior to our first observation of drinking, however, is unlikely. It is equally unlikely that if pronghorns did drink during winter, that it only occurred at night.

We observed no difference among seasons (except winter) in percentage of time that Sonoran pronghorns drank. Other studies, however, have shown seasonal variation in amount of free water consumed by ruminants and its positive correlation with ambient temperatures (Beale and Smith, 1970; Jarman, 1973). Sonoran pronghorns in this study could have exhibited seasonal variation in amount of freewater consumed if they increased the volume of freewater consumed per unit of time, or drank at night (which has been observed; T. Tibbitts, pers. comm.). Drinking at night might occur regularly for Sonoran pronghorns because nocturnal activity of other desert-dwelling ungulates has been documented Uarman and Jarman, 1973; Krausman et al., 1985; Hayes and Krausman, 1993).

Sonoran pronghorns groomed their young for a similar period of time as reported for other populations (3-5 weeks; Kitchen, 1974), although Byers (1997) reported that one component of what we defined as grooming (i.e., licking the perianal region; Table 1) did not cease until ca. 6 weeks of age. Weaning also was similar to other reports (Buechner, 1950; Kitchen, 1974; Autenrieth and Fichter, 1975; Byers, 1997).

This study provides the first seasonal diurnal activity budgets for Sonoran pronghorns and also complements limited data on foraging, drinking, and maternal behavior of free-ranging Sonoran pronghorns. The results help to elucidate how Sonoran pronghorns cope with a harsh environment at the southern edge of their range and how their behavior might change during drought. Our study occurred in the most natural conditions possible in captivity. Due to changes in management of captive Sonoran pronghorns (i.e., initiation of supplemental feeding), these might be the only data collected on activity due to limitations of studying their behavior in the wild. We believe these data represent an integral component to furthering our understanding of basic behavior of Sonoran pronghorns and can be used to assist in recovery of this endangered subspecies.

Our results indicate that temperature and availability of forage influence behavior of Sonoran pronghorns. We documented that Sonoran pronghorns used water regularly. Because availability of water potentially can affect foraging behavior and quality of diet (Lautier et al., 1988; Fox et al., 2000), existing water developments should be maintained and additional water developments considered. Activity budgets developed in this study also might be useful in refinement of sightability models used to estimate size of the population of Sonoran pronghorns (Risenhoover, 1986). Our results also support the idea that behavioral data from adjacent populations might be used as a surrogate when data cannot be obtained directly from Sonoran pronghorns.

Associate Editor was Celia Lopez-Gonzalez.

We thank the staff at Cabeza Prieta National Wildlife Refuge for assistance, especially C. S. McCasland, M. P. Coffeen, M. A. Bissell, and T. W. Henley. We also thank the Arizona Game and Fish Department for assistance. J. P. Marshal, B. D. Jansen, J. W. Cain, III, J. D. Yoakum, and J. L. Koprowski provided valuable comments and discussion throughout this study. J. D. Yoakum and J. L. Koprowski reviewed an early version of the manuscript. We also thank three anonymous reviewers for detailed comments that greatly improved the manuscript. We thank M. Rivera Soldevilla for translating the abstract into Spanish. This study was funded by the United States Fish and Wildlife Service, United States Geological Survey, United States Fish and Wildlife Foundation, and T&E, Inc.

Submitted 19 November 2007. Accepted I September 2008.


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School of Natural Resources, University of Arizona, Tucson, AZ 85721 (RRW, PRK) United States Fish and Wildlife Service, P.O. Box 1306, Albuquerque, NM 87103 (JRM) Present address of RRW Department of Wildland Resources, Utah State University, Logan, UT 84322 Present address of PRK College of Forestry and Conservation, Wildlife Biology Program, 32 Campus Drive, University of Montana, Missoula, MT 59812

* Correspondent:
TABLE 1--Description of behaviors recorded for Sonoran pronghorns
(Antilocapra americana sonoriensis) in a semi-captive breeding
facility, Cabeza Prieta National Wildlife Refuge, Pima Co.,
Arizona, 2005.

Behavior Description

Foraging Consuming or searching for forage
Standing Standing, but not defecating,
 urinating, or consuming forage
 Ruminating or Standing ruminating or standing
 not ruminating not ruminating
Traveling Running, trotting, or walking with
 head up (not searching for forage)
Bedded Lying prone on ground
 Sun or shade Bedded in sun or shade
 Ruminating or Bedded ruminating or bedding
 not ruminating not ruminating
Maternal behavior Any nursing or grooming activity
 between females and young
 Nursing Females standing allowing young
 to nurse, young not groomed
 Grooming young Female grooming young or licking
 perianal region, not nursing
 Nursing while Both grooming and nursing occurring
 grooming young simultaneously
Drinking Head below top of water trough

TABLE 2--Percentage of time adult female Sonoran
pronghorns (Antilocapra americana sonoriensis n = 6)
devoted to each of five categories of behavior by
season in a semi-captive breeding facility on Cabeza
Prieta National Wildlife Refuge, Pima Co., Arizona, 2005

 Behavior (a)

 Foraging Bedding Standing

Season [chi SE [chi SE [chi SE
 square] square] square]

Winter 41.6A 1.6 20.3A 1.3 20.2A 1.5
Spring 45.8AB 1.8 14AAB 1.5 24.6AB 1.2
Summer 41.6AB 2.0 14.8B 1.5 26.4B 1.6
Autumn 56.2C 2.2 16.0AB 2.2 13.0C 0.9

 Behavior (a)

 Traveling Drinking

Season [chi SE [chi SE
 square] square]

Winter 14.7A 1.4 0.0A 0.0
Spring 12.6A 2.4 1.1B 0.1
Summer 15.4A 1.0 0.8B 0.1
Autumn 13.8A 0.9 0.8B 0.1

(a) Different letters indicate differences (P < 0.05) between seasons
within a behavior based on Bonferroni corrected ([alpha] = 0.05/6)
paired t-tests.

TABLE 3--Percentage of time adult female Sonoran pronghorns
(Antilocapra americana sonoriensis n = 6) seasonally foraged on
different classes of forage in a semi-captive breeding facility,
Cabeza Prieta National Wildlife Refuge, Pima Co., Arizona, 2005.
We lumped forbs and grasses into one category because of
difficulty in distinguishing between them due to observational

 Class of forage (a)

 Forb-grass Shrub
Season [bar.x] SE [bar.x] SE

Winter 59.1A 5.4 39.7A 6.3
Spring 13.6B 2.4 11.3B 1.9
Summer 3.5B 1.2 61.4A 4.8
Autumn 4.9B 2.6 24.9AB 4.9

 Class of forage (a)

 Tree Cactus
Season [bar.x] SE [bar.x] SE

Winter 0.5A 0.5 0.7A 0.7
Spring 72.1B 3.3 2.9A 1.1
Summer 31.1C 4.1 4.0A 1.3
Autumn 56.9BC 7.6 13.3A 7.5

(a) Different letters indicate differences (P < 0.05)
among seasons within a forage class based on Bonferroni
corrected ([alpha] = 0.05/6) paired t-tests.
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Author:Wilson, Ryan R.; Krausman, Paul R.; Morgart, John R.
Publication:Southwestern Naturalist
Article Type:Report
Geographic Code:1USA
Date:Mar 1, 2009
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