Variation in herpetofauna detection probabilities: implications for study design.

Population monitoring is fundamental for informing management decisions aimed at reducing the rapid rate of global biodiversity decline. Herpetofauna are experiencing declines worldwide and include species that are challenging to monitor. Raw counts and associated metrics such as richness indices are common for monitoring populations of herpetofauna; however, these methods are susceptible to bias as they fail to account for varying detection probabilities. Our goal was to develop a program for efficiently monitoring herpetofauna in southern Texas. Our objectives were to (1) estimate detection probabilities in an occupancy modeling framework using trap arrays for a diverse group of herpetofauna and (2) to evaluate the relative effectiveness of funnel traps, pitfall traps, and cover boards. We collected data with 36 arrays at 2 study sites in 2015 and 2016, for 2105 array-days resulting in 4839 detections of 51 species. We modeled occupancy for 21 species and found support for the hypothesis that detection probability varied over our sampling duration for 10 species and with rainfall for 10 species. For herpetofauna in our study, we found 14 and 12 species were most efficiently captured with funnel traps and pitfall traps, respectively, and no species were most efficiently captured with cover boards. Our results show that using methods that do not account for variations in detection probability are highly subject to bias unless the likelihood of false absences is minimized with exceptionally long capture durations. For monitoring herpetofauna in southern Texas, we recommend using arrays with funnel and pitfall traps and an analytical method such as occupancy modeling that accounts for variation in detection.

Evaluation of roost culling as a management strategy for reducing invasive rose-ringed parakeet (Psittacula krameri) populations.

Rose-ringed parakeets (Psittacula krameri) are one of the most widespread invasive avian species worldwide. This species was introduced to the island of Kaua'i, Hawai'i, USA, in the 1960s. The rapidly increasing population has caused substantial economic losses in the agricultural and tourism industries. We evaluated the efficacy of a roost culling program conducted by an independent contractor from March 2020 to March 2021. We estimated island-wide minimum abundance was 10,512 parakeets in January 2020 and 7,372 in April 2021. Over 30 nights of culling at four roost sites, approximately 6,030 parakeets were removed via air rifles with 4,415 (73%) confirmed via carcasses retrieval. An estimated average of 45 parakeets were removed per hour of shooter effort. The proportion of adult females removed in 2020 was 1.9 × greater when culled outside of the estimated nesting season. Of the four roosts where culling occurred, the parakeets fully abandoned three and partially abandoned one site. Of the three fully abandoned roosts, an estimated average of 29.6% of birds were culled prior to roost abandonment. The roost culling effort was conducted during the COVID-19 pandemic, when tourist numbers and foot traffic were greatly reduced. It is unknown how public perception of roost culling in public areas may impact future efforts. Findings suggest roost culling can be utilized for management of nonnative rose-ringed parakeet populations when roost size is small enough and staff size large enough to cull entire roosts in no greater than two consecutive nights (e.g., if two shooters are available for three hours per night, roost culling should only be attempted on a roost with ≤ 540 rose-ringed parakeets). Supplementary Information: The online version contains supplementary material available at 10.1007/s10530-022-02984-3.

Wildlife Undergrads Spread Their Wings in Citizen Science Research Experience.

Citizen science has become a valuable tool for natural resource professionals; however, many undergraduate students are not aware of its use as a means of collecting data for scientific analysis. To address this, we introduced a bird-focused research experience into an undergraduate Wildlife Management Techniques course. The objective of this course is to provide practical experiences in wildlife science by learning and using tools and techniques applied in the field. Students designed, implemented, and presented the results of a wild bird observation survey that contributed data to an existing e-Bird-based program. Pre-post surveys were collected to assess student learning and behavioral changes. We observed increased student awareness of citizen science. Ninety-two percent of students correctly defined citizen science following the experience. However, only sixteen percent of students stated they would continue participation in STWB, fifty percent were unsure, and thirty-four percent would not continue involvement. Improvements are discussed to promote participation in citizen science, connections with the community, and communication skill development for future employment.

Ecomorphological relationships of a guild of ground-foraging birds in northern California, USA.

We studied habitat and morphological relationships of nine species of birds comprising a groundforaging guild within four distinct locations in northern California. Although the nine species overlapped extensively in habitat use, we observed subtle differences among species in specific characteristics of the habitats they used. About 40% of all cases were classified to the correct species based on a discriminant analysis (DA) of habitats across all study areas. Classification success from DAs on habitats within study areas ranged from 42 to 66%. Morphologies of species differed to varying degrees as 91% of all cases were classified to correct species by a DA of morphological variables. This morphological separation suggested that each species used different modes of obtaining resources. We found only weak relationships between habitat use and morphology. Morphology predicted from 13.6 to 19.0% of the variation in habitat use within each study area and only 13.9% of the habitat variation across all study areas. Habitat predicted from 6.2 to 14.6% of the morphological variation within each study area and 6.9% across all study areas. We suggest that complimentary relationships of habitat and morphology enabled species within this guild to use unique sets of resources.