Aridland riparian forests are undergoing compositional changes in vegetation and wildlife communities due to altered hydrology. As flows have been modified, woody vegetation has shifted from native‐tree dominated to non‐native and shrub encroached habitats. Squamate vertebrates such as lizards and snakes are important food web links in riparian ecosystems of the Sonoran Desert. However, little is known about how these communities might respond as riparian forests transition from native tree dominated habitats to open xeroriparian woodlands. We used pitfall arrays deployed across three types of riparian forest to document reptile community patterns, measure vegetation, and produce species‐habitat models. Riparian forests differed on the basis of habitat composition and physiognomy. Two types, cottonwood‐willow (Populus‐Salix) and mesquite (Prosopis) stands, were characterized by high woody species richness. The third type, non‐native saltcedar (Tamarix) stands, had high densities of woody debris and greater canopy coverage. Results show that lizards were common and abundances greatest in cottonwood‐willow, especially for arboreal species. Species‐habitat models for three of five lizard species indicated a negative association to saltcedar‐invaded habitat and no species appeared to select saltcedar‐dominated habitat. Mesquite was an intermediate habitat between upland and riparian, and supports high species diversity. A wildfire in the cottonwood‐willow forest disproportionately affected abundance of ground‐foraging whiptail (Aspidoscelis) lizards; whereas, abundance of arboreal spiny (Sceloporus) species was unchanged. Expected drivers from climate and water use could transition cottonwood forests to other woody‐dominated types. Our results suggest that mesquite woodlands would provide higher quality habitat for riparian reptiles compared to non‐native saltcedar stands.
Passive acoustic recorders have been used successfully as automated survey tools to detect terrestrial wildlife. However, few studies have monitored Neotropical migratory bird use of riparian forest habitat using this technology. Within dryland ecosystems, the forests along rivers support high bird diversity. Many bird species of conservation concern require these floodplain forest habitats for foraging, migration stop-overs, and breeding. Few studies have explored the use of acoustic records in riverine systems designated for conservation for their natural resource value via the Wild and Scenic Rivers Act in the USA. Using acoustic recorders, we document vocal activity of four riparian-obligate species (Bell’s Vireo, Vireo bellii; Summer Tanager, Piranga rubra; Yellow Warbler, Setophaga petechial; and Yellow-billed Cuckoo, Coccyzus americanus) to determine species occurrence along a Wild and Scenic River. We established three study reaches along the perennial Lower Verde River, in the Sonoran Desert of central Arizona, USA. Nine acoustic recorders were used over the period of 80–120 days during the summer of 2018. We measured vegetation composition and structure in 100 m2 plots paired with acoustic recorders. Visualizing vocal activity showed that three species were calling and singing at each reach; whereas, one species, the cuckoo, had fewer recordings and occurred later in the summer. We demonstrate the utility of acoustic monitoring even when applied to rare birds in complex riparian habitats. This information is important for land management and conservation efforts concerning these species of interest and identifying important habitat features in Southwestern US riparian woodlands.
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