Michael J. Rabe

Wildlife Use of Water Catchments in Southwestern Arizona

Abstract Construction of water developments has been used as a wildlife-habitat improvement technique in desert environments since the 1940s. Use of water developments by wildlife has been described in anecdotal observations, through water-hole counts, and with triggered still-cameras, but few studies have directly quantified wildlife use. We used video surveillance equipment to document wildlife use of 3 water catchments located in the Sonoran Desert, southwestern Arizona, USA, from June 2000 to November 2003. For each visitation, we recorded time of day, season of use, and activities engaged in, and we correlated visits with temperature and relative humidity. We logged 37,989 observation hours and documented 34 species using the water catchments. Most of the species recorded visited water catchments year-round with use peaking during June and July. The number of visits by nongame species (i.e., bats, raptors, mammalian predators, and rodents) exceeded the number of visits by game species (mule deer [Odocoileus hemionus], doves [Zenaida spp.], and Gambels quail [Callipepla gambelii]). Visitation frequency for turkey vultures (Cathartes aura), owls, diurnal raptors, mule deer, coyotes (Canis latrans), and other mammalian predators increased with temperature. Most visits culminated in the animal drinking water. Other activities recorded were bathing, consumption of plant material and carrion, and intraspecies and interspecies interactions. We recorded 8 predation attempts: 4 by avian predators and 4 by bobcats (Lynx rufus). Although we documented that a number of species frequented water catchments, our observations do not prove need. However, we believe our observations do provide support for constructing water catchments that can accommodate a wide diversity of species.

SELECTION OF GAMBEL OAK ROOSTS BY SOUTHWESTERN MYOTIS IN PONDEROSA PINE-DOMINATED FORESTS, NORTHERN ARIZONA

Abstract Gambel oak (Quercus gambelii) is a valuable tree species for wildlife. In Arizona, USA, it occurs at higher elevations in association with ponderosa pine (Pinus ponderosa). Southwestern myotis (Myotis auriculus) is a bat species that has been anecdotally documented as selecting Gambel oak for maternity roost sites. During summers of 1999 and 2000, we conducted a radiotelemetry study to determine whether lactating, female southwestern myotis selected Gambel oak as maternity roosts within the ponderosa pine–Gambel oak forest in northern Arizona. We located 34 maternity roosts for southwestern myotis in Gambel oak trees (14 females) and 5 roosts in ponderosa pine snags (1 female). Maternity roosts were located in live Gambel oak trees >26-cm diameter at root collar (drc) that contained cavities. We used Akaikes Information Criterion (AIC) to evaluate 4 a priori hypotheses about southwestern Myotis maternity roost selection in northern Arizona. Our top model contained parameters for roost tree height and density of potential roost trees. Roost trees were taller than randomly selected Gambel oak trees. Forest patches immediately surrounding roost trees contained a higher density of large oak trees (drc >26 cm) than around randomly selected trees. We recommend the protection of large Gambel oak trees and encourage recruitment of large Gambel oak trees from smaller size classes to ensure that roosts remain available for southwestern myotis.

FERAL AFRICANIZED HONEY BEES (APIS MELLIFERA) IN SONORAN DESERT HABITATS OF SOUTHWESTERN ARIZONA

Abstract Africanized honeybees, hybrids between African (Apis mellifera scutellata) and western European (A. m. mellifera) and eastern European (A. m. caucasica, A. m. carnica, and A. m. ligustica) subspecies are widely distributed in urban areas of the southwestern USA. However, little is known about their distribution in rural regions. We collected bees at 54 sites in a 5,350-km2 study area in the Sonoran Desert of southwestern Arizona. We used mitochondrial DNA (mtDNA) analysis of individual worker honeybees (10 per site) to assess genetics of colonies within the study area. Among collected bees, 86.9% possessed African mtDNA. Western European, eastern European, and Egyptian (A. m. lamarckii) mtDNA was present in 5.6%, 4.1%, and 3.4% of collected bees, respectively. There was no apparent relationship between the percentage of bees having African mtDNA and distance to agricultural fields or elevation of the collection site. The preponderance of Africanized honeybees confirms previous studies and predictions concerning their distribution in the southwestern USA.

Water Quality at Wildlife Water Sources in the Sonoran Desert, United States

Abstract Surface water is an important limiting factor for wildlife populations in desert environments where water sources are uncommon or have been lost or degraded due to human activities. To address this need, wildlife water developments have been constructed in many areas of the southwestern United States, particularly in the Sonoran Desert. Previous studies of wildlife water developments are limited and critics have asserted that water quality at these facilities may be deleterious to animal health. Water quality was evaluated at natural, modified natural, and constructed water sources in the Sonoran Desert of southwestern Arizona and southeastern California. Samples were taken from primary sources of surface water available to wildlife, including natural tinajas (rock basins), modified tinajas, springs, rainwater catchments (“guzzlers”), and wells. Water samples were tested for 21 chemical constituents known to affect animal health, blue-green algal toxins, and a presumed waterborne pathogen, the protozoan avian parasite Trichomonas gallinae. Seven chemical constituents were absent or below detection limits. The majority of constituents detected (10/13, 77%) occurred at levels below recommended guidelines for domestic animals. Elevated pH, alkalinity, and fluoride were found in rainwater catchments, springs, and wells, respectively, but at relatively low levels unlikely to affect animal health. Blue-green algal toxins were not detected and there was no evidence of Trichomonas. Although specific water quality guidelines for wildlife are lacking, these results do not support hypothesized negative impacts to wildlife populations from developed water sources.

Reducing Lead on the Landscape: Anticipating Hunter Behavior in Absence of a Free Nonlead Ammunition Program.

Lead is a neurotoxin that has been documented to affect many forms of wildlife, and has been identified as a limiting factor in a population of California Condors in Northern Arizona. The Arizona Game and Fish Department provides vouchers for free nonlead ammunition to hunters selected to hunt within the distribution of California Condors, with the intention of having fewer lead-laden offal piles available to California Condors. Although wildlife agencies may reasonably assume voucher programs motivate hunters into choosing nonlead ammunition, the lead reduction efforts attributable to the voucher program has not been empirically quantified. Our intention was to compare a control group of hunters to a treatment group of hunters within California Condor occupied areas. Both groups received educational materials regarding the deleterious effects of lead, but the treatment group also received a voucher for a free initial box of ammunition. About half of the control group used nonlead ammunition, compared to about three-fourths of the treatment group. Prominent barriers to adoption of nonlead ammunition included a general difficulty of obtaining it, obtaining it in the desired caliber, and its costliness. Frequently mentioned motivations for using nonlead was the exhortation to use it by the Department, and the desire to aid California Condor recovery by hunters. The disparate compliance rates found herein confirm and quantify the success of nonlead ammunition voucher programs, but underscore the importance of working to increase the supply of nonlead ammunition with the end of facilitating its procurement and reducing its cost.

MULTISTATE ANALYSIS OF FIXED, LIBERAL REGULATIONS IN QUAIL HARVEST MANAGEMENT

Abstract We derived consequences (realizations of hunter efficiency, relative harvest rates) of fixed, liberal quail (northern bobwhite [Colinus virginianus], Gambels quail [Callipepla gambelii], and scaled quail [C. squamata]) harvest regulations applied at large scales from time series on quail abundance, total harvest, and hunter participation. Data came from Kansas (1966–2001), Missouri (1983–2001), Oklahoma (1990–2001), north and south Texas (1986–2001), and Arizona (1982–1999), USA, where harvest regulations were liberal (season length 2.5–4 months, daily bag limit 8–15 birds) during the periods of record. For all study regions, hunter-days were expressible as a linear function of quail abundance, and total harvest was expressible as a linear function of hunter-days. These results implied that hunter efficiency (harvest/hunter-day/index bird) declined monotonically and curvilinearly as quail populations increased. Likewise, relative harvest rate declined monotonically and curvilinearly as abundance increased, which implied that harvest was not self-limiting; however, the rate of decline generally was low because harvest rate was the product of an increasing (hunter-days) and a decreasing function (hunter efficiency) of quail abundance. Under fixed, liberal regulations, variations in quail abundance seem to govern harvest rates at the state or regional level; the regulations per se probably are biologically inconsequential.