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Burrowing Owls (Athene cunicularia) have experienced significant population declines over the last 100 years in parts of the United States and Canada. This decline may be associated with increasing urbanization and land-cover change; however, owls can occupy urbanized environments. To determine habitat selection in the southeast valley of Phoenix, Arizona, we conducted visual surveys for owls during summer 2011 and measured microhabitat and landscape characteristics in 23 agricultural fields (fields) and along 15 canal right-of-ways (trails). We estimated occupancy rate and detectability using Program MARK. We identified microhabitat selection to relate owl occurrence to landscape variables. Occupancy rate was 32% in both fields and trails and owls had greater detectability along trails. Burrowing Owl occurrence was similar in fields with varying agricultural stages (from undisturbed to harvested) and moisture conditions. Owl occupancy was positively associated with soil type and canal water presence, and occupancy decreased when developed landscape cover (e.g., roads and buildings) increased. These findings suggest that Burrowing Owls are able to live in urbanized environments below 40% developed land cover provided that water and suitable soils are available.
Most fish use suction to capture prey, which is effective on a wide variety of items. However, it is ineffective on attached prey, which require a biting or scraping mode of food acquisition. Members of the Cyprinodontiformes, however, are unusual in that they use a biting mode of prey capture on water column prey. The swordtail, Xiphophorus helleri, is a member of this clade that feeds both in the water column and grazes on the benthos. We sought to determine if swordtails would modulate prey capture mechanics in response to varying food types and presentations. “Blood worms” (chironomid larvae) and brine shrimp served as prey of differing sizes that could be caught in the water column, presumably via differing levels of inertial suction. These were compared with commercial algae tabs that served as a benthic prey item, which should elicit biting or scraping. Prey capture was recorded using high-speed video at 250 frames per second. Sequences were analyzed frame by frame to track movement of the jaws during the feeding event. We found that when feeding in that water column, both maximum gape distance and maximum premaxillary protrusion were smaller than during bottom feeding. Bottom-feeding events were slower and more exaggerated, characteristic of scraping food capture.
This paper reports on the reproductive seasonality and developmental characteristics of Page springsnail (Pyrgulopsis morrisoni) observed for two consecutive years in a carefully monitored ex-situ population housed at the Phoenix Zoo's Conservation Center. During 2010 and 2011, Page springsnails exhibited seasonal reproductive activity beginning in mid-July and continuing through November each year, with peak reproductive activity occurring from August to October which differs from previously reported observations. An isolated group of Page springsnails photographed, described and measured weekly for 10 weeks beginning in July in order to determine the rate and characteristics of development. The females deposited a single egg at a time and there was an 8-to-10-day interval between the detection of newly emerged snails. Juvenile snails emerged at 0.3 mm to ≥0.4 mm and reached adult size of at least 2.5 mm with three whorls present, after approximately 6 weeks. The maximum adult snail size recorded in the collection was 3.9 mm, but we only observed one snail at that size.
The antelope jackrabbit, Lepus alleni occurs from south-central Arizona, southward to northern Nayarit, Mexico. In Arizona and the northern part of Sonora the species is sympatric with Lepus californicus. Lepus alleni belongs to the white-sided jackrabbit group of the genus, which separated from a common ancestor to Lepus californicus ∼1.2 MYBP. Genetic evidence indicates that this white-sided jackrabbit group separated into at least three species during the Pleistocene, while L. californicus expanded its range. We contend that L. alleni is a tropic-subtropic species restricted to remnant savannas and those more mesic portions of the Sonoran Desert where summer precipitation and humidity are adequate, and to areas of maritime dew lacking L. californicus. Not only is L. californicus better adapted to aridity, this species is also able to tolerate relatively cold temperatures. L. alleni is confined to habitats having mean annual temperatures between 20°C and 60°C, and goes into hypothermia when body temperatures drop to 28°C. The adaptive advantages of the antelope jackrabbit are its larger size (553–670 mm) allowing for greater heat retention, mobility, feeding on taller vegetation, and ability to peer over taller cover. These morphological and physiological adaptations of L. alleni to climatic conditions and environmental changes are closely related to its evolutionary history. This has restricted this species to habitats with moderate environmental characteristics.
Fungi in the genus Armillaria are associated with an important disease of deciduous and coniferous trees and shrubs in western North America. This study examined the distribution of Armillaria by forest habitat types on the Kaibab National Forest and northern Coconino National Forest, Arizona. Over 400 trees were examined for Armillaria in 76 Interior West Forest Inventory and Analysis permanent plots representing 17 different habitat types. Samples of the fungus associated with Armillaria root disease were collected from 23 trees and identified using DNA sequencing. All samples were determined to consist of a single species, Armillaria solidipes Peck [= A. ostoyae (Romagnesi) Herink]. Only 10 of the 76 plots and 5 of the 17 habitat types sampled had Armillaria solidipes present on one or more trees. A. solidipes was more commonly found in mixed-conifer and subalpine forests and was rare in ponderosa pine (Pinus ponderosa Doug. Ex. Larson & C. Larson) forests, which was consistent with previous root disease studies conducted in the Southwest. However, our estimates of Armillaria presence may be conservative since we did not examine entire root systems.
Naturally occurring sulfates are common contaminants of groundwater. Dissolved sulfates are used by sulfate reducing bacteria which release hydrogen sulfide. Sulfate reducing bacteria are common in anaerobic environments such as deep wells. This results in production of hydrogen sulfide, a corrosive gas. Monitoring and control of sulfate reducing bacteria may be used to control the formation of hydrogen sulfide. To this end, the present study examined the prevalence of sulfate-reducing bacteria from five groundwater sources on the Mogollon Rim in central Arizona. The five samples were negative by both assays. Results serve as a basis for future study of ground-water microbiology and sulfate-reducing geochemistry in the Mogollon Rim.