Habitat heterogeneity is necessary to support reptile species diversity and abundance. In the Nor... more Habitat heterogeneity is necessary to support reptile species diversity and abundance. In the North American Desert Southwest, there is little information regarding habitat preferences that influence reptile community occupancy. In south central New Mexico, we sampled reptiles on Holloman Air Force Base (HAFB) in relatively undisturbed habitat within gypsum sand dunes and clay/loamy soil to determine species richness and relative abundance using Occupancy Modeling. Species were intensively surveyed using pitfall traps, funnels traps, road cruising and active searching. We found six species of lizards, five species of snakes, and one turtle; lizards being more abundant, particularly the Common Side-blotched (Uta stansburiana) and Little Striped Whiptail (Aspidoscelis inornata) lizards. We also related reptile species assemblages to habitat gradients (cover and soil type) using Canonical Correspondence Analysis (CCA). Uta stansburiana, A. inornata, and Eastern Collared Lizards (Crotaphytus collaris) were the only reptiles observed at a high enough frequency to analyze their habitat associations using CCA. Uta stansburiana had a close association with bare ground, A. inornata was associated with clay/loamy soil, and C. collaris was most closely associated with greater densities of grasses and forbs. There may be confounding influences on the lack of reptile species detected, most notably precipitation, given persistent drought conditions in the Desert Southwest. After rain events resume, it may be necessary to re-examine reptile composition and their habitat associations to investigate the re-establishment and recruitment abilities of these arid-adapted species.
One-third of known amphibian populations have become extinct, with habitat loss and degradation b... more One-third of known amphibian populations have become extinct, with habitat loss and degradation being the leading causes in the United States. Site occupancy has been suggested as one of the most effective state variables in describing population declines. The objectives of this study were to determine occupancy estimates of five southwestern desert anurans, accounting for imperfect detection, and to determine the main factors impacting detection. We conducted call and visual surveys on three consecutive nights after rain events at 21 breeding sites for Mexican Spadefoot (Spea multiplicata), Plains Spadefoot (Spea bombifrons), Couch’s Spadefoot (Scaphiopus couchii), Great Plains Toad (Anaxyrus cognatus), and Green Toad (Anaxyrus debilis). We used occupancy modeling to estimate the proportion of sites occupied for all species detected during the sampling period. Spea multiplicata and A. debilis were most prevalent, followed by A. cognatus, Sp. bombifrons, and Sc. couchii, respectively. In addition to the inclusion of repeated site surveys to decrease bias, incorporating visual surveys greatly improved occupancy estimates for southwestern desert anurans. Detection was highest on survey night one for Sp. multiplicata, Sp. bombifrons, Sc. couchii, and A. debilis (72.2–100%); warmer air temperature improved detection of A. cognatus. Sky conditions did not significantly influence desert anuran detectability. Immediate survey after rain events and the combination of call and visual surveys are critical to increase accuracy when studying desert anurans.
Habitat heterogeneity is necessary to support reptile species diversity and abundance. In the Nor... more Habitat heterogeneity is necessary to support reptile species diversity and abundance. In the North American Desert Southwest, there is little information regarding habitat preferences that influence reptile community occupancy. In south central New Mexico, we sampled reptiles on Holloman Air Force Base (HAFB) in relatively undisturbed habitat within gypsum sand dunes and clay/loamy soil to determine species richness and relative abundance using Occupancy Modeling. Species were intensively surveyed using pitfall traps, funnels traps, road cruising and active searching. We found six species of lizards, five species of snakes, and one turtle; lizards being more abundant, particularly the Common Side-blotched (Uta stansburiana) and Little Striped Whiptail (Aspidoscelis inornata) lizards. We also related reptile species assemblages to habitat gradients (cover and soil type) using Canonical Correspondence Analysis (CCA). Uta stansburiana, A. inornata, and Eastern Collared Lizards (Crotaphytus collaris) were the only reptiles observed at a high enough frequency to analyze their habitat associations using CCA. Uta stansburiana had a close association with bare ground, A. inornata was associated with clay/loamy soil, and C. collaris was most closely associated with greater densities of grasses and forbs. There may be confounding influences on the lack of reptile species detected, most notably precipitation, given persistent drought conditions in the Desert Southwest. After rain events resume, it may be necessary to re-examine reptile composition and their habitat associations to investigate the re-establishment and recruitment abilities of these arid-adapted species.
One-third of known amphibian populations have become extinct, with habitat loss and degradation b... more One-third of known amphibian populations have become extinct, with habitat loss and degradation being the leading causes in the United States. Site occupancy has been suggested as one of the most effective state variables in describing population declines. The objectives of this study were to determine occupancy estimates of five southwestern desert anurans, accounting for imperfect detection, and to determine the main factors impacting detection. We conducted call and visual surveys on three consecutive nights after rain events at 21 breeding sites for Mexican Spadefoot (Spea multiplicata), Plains Spadefoot (Spea bombifrons), Couch’s Spadefoot (Scaphiopus couchii), Great Plains Toad (Anaxyrus cognatus), and Green Toad (Anaxyrus debilis). We used occupancy modeling to estimate the proportion of sites occupied for all species detected during the sampling period. Spea multiplicata and A. debilis were most prevalent, followed by A. cognatus, Sp. bombifrons, and Sc. couchii, respectively. In addition to the inclusion of repeated site surveys to decrease bias, incorporating visual surveys greatly improved occupancy estimates for southwestern desert anurans. Detection was highest on survey night one for Sp. multiplicata, Sp. bombifrons, Sc. couchii, and A. debilis (72.2–100%); warmer air temperature improved detection of A. cognatus. Sky conditions did not significantly influence desert anuran detectability. Immediate survey after rain events and the combination of call and visual surveys are critical to increase accuracy when studying desert anurans.
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Papers by Niki Harings
In south central New Mexico, we sampled reptiles on Holloman Air Force Base (HAFB) in relatively undisturbed habitat
within gypsum sand dunes and clay/loamy soil to determine species richness and relative abundance using Occupancy
Modeling. Species were intensively surveyed using pitfall traps, funnels traps, road cruising and active searching. We
found six species of lizards, five species of snakes, and one turtle; lizards being more abundant, particularly the Common
Side-blotched (Uta stansburiana) and Little Striped Whiptail (Aspidoscelis inornata) lizards. We also related reptile
species assemblages to habitat gradients (cover and soil type) using Canonical Correspondence Analysis (CCA). Uta
stansburiana, A. inornata, and Eastern Collared Lizards (Crotaphytus collaris) were the only reptiles observed at a high
enough frequency to analyze their habitat associations using CCA. Uta stansburiana had a close association with bare
ground, A. inornata was associated with clay/loamy soil, and C. collaris was most closely associated with greater densities
of grasses and forbs. There may be confounding influences on the lack of reptile species detected, most notably precipitation, given persistent drought conditions in the Desert Southwest. After rain events resume, it may be necessary to re-examine reptile composition and their habitat associations to investigate the re-establishment and recruitment abilities of these arid-adapted species.
most effective state variables in describing population declines. The objectives of this study were to determine occupancy estimates of five southwestern desert anurans, accounting for imperfect detection, and to determine the main factors impacting detection. We conducted call and visual surveys on three
consecutive nights after rain events at 21 breeding sites for Mexican Spadefoot (Spea multiplicata), Plains Spadefoot (Spea bombifrons), Couch’s Spadefoot (Scaphiopus couchii), Great Plains Toad (Anaxyrus
cognatus), and Green Toad (Anaxyrus debilis). We used occupancy modeling to estimate the proportion of sites occupied for all species detected during the sampling period. Spea multiplicata and A. debilis were most prevalent, followed by A. cognatus, Sp. bombifrons, and Sc. couchii, respectively. In addition to the inclusion
of repeated site surveys to decrease bias, incorporating visual surveys greatly improved occupancy estimates for southwestern desert anurans. Detection was highest on survey night one for Sp. multiplicata, Sp. bombifrons, Sc. couchii, and A. debilis (72.2–100%); warmer air temperature improved detection of A. cognatus. Sky conditions did not significantly influence desert anuran detectability. Immediate survey after
rain events and the combination of call and visual surveys are critical to increase accuracy when studying desert anurans.
In south central New Mexico, we sampled reptiles on Holloman Air Force Base (HAFB) in relatively undisturbed habitat
within gypsum sand dunes and clay/loamy soil to determine species richness and relative abundance using Occupancy
Modeling. Species were intensively surveyed using pitfall traps, funnels traps, road cruising and active searching. We
found six species of lizards, five species of snakes, and one turtle; lizards being more abundant, particularly the Common
Side-blotched (Uta stansburiana) and Little Striped Whiptail (Aspidoscelis inornata) lizards. We also related reptile
species assemblages to habitat gradients (cover and soil type) using Canonical Correspondence Analysis (CCA). Uta
stansburiana, A. inornata, and Eastern Collared Lizards (Crotaphytus collaris) were the only reptiles observed at a high
enough frequency to analyze their habitat associations using CCA. Uta stansburiana had a close association with bare
ground, A. inornata was associated with clay/loamy soil, and C. collaris was most closely associated with greater densities
of grasses and forbs. There may be confounding influences on the lack of reptile species detected, most notably precipitation, given persistent drought conditions in the Desert Southwest. After rain events resume, it may be necessary to re-examine reptile composition and their habitat associations to investigate the re-establishment and recruitment abilities of these arid-adapted species.
most effective state variables in describing population declines. The objectives of this study were to determine occupancy estimates of five southwestern desert anurans, accounting for imperfect detection, and to determine the main factors impacting detection. We conducted call and visual surveys on three
consecutive nights after rain events at 21 breeding sites for Mexican Spadefoot (Spea multiplicata), Plains Spadefoot (Spea bombifrons), Couch’s Spadefoot (Scaphiopus couchii), Great Plains Toad (Anaxyrus
cognatus), and Green Toad (Anaxyrus debilis). We used occupancy modeling to estimate the proportion of sites occupied for all species detected during the sampling period. Spea multiplicata and A. debilis were most prevalent, followed by A. cognatus, Sp. bombifrons, and Sc. couchii, respectively. In addition to the inclusion
of repeated site surveys to decrease bias, incorporating visual surveys greatly improved occupancy estimates for southwestern desert anurans. Detection was highest on survey night one for Sp. multiplicata, Sp. bombifrons, Sc. couchii, and A. debilis (72.2–100%); warmer air temperature improved detection of A. cognatus. Sky conditions did not significantly influence desert anuran detectability. Immediate survey after
rain events and the combination of call and visual surveys are critical to increase accuracy when studying desert anurans.