Landbird monitoring in the Southern Plains Network: 2016 annual report

Ali, Moez; Bonebrake, Kristen; Valentine-Darby, Patricia; Lien, Lauren

In 2016, landbirds were surveyed within all of the Southern Plains Inventory & Monitoring Network (SOPN) parks. However, Alibates Flint Quarries National Monument (NM) and Lake Meredith National Recreation Area (NRA) were treated as one park unit, and no sampling was specifically conducted at Alibates Flint Quarries NM. Sample points were located along a transect for linear features (e.g., most riparian habitats) or a grid for areal features. A total of 34 transects or grids was surveyed in 2016. Survey efforts were focused on the breeding season, when increased territorial behavior by songbirds results in higher detection rates and greater sampling efficiency. The window of primary breeding and, therefore, sampling, was from April through June, with adjustments made for individual park visits based on latitude and elevation. To estimate and monitor landbird population parameters, we sampled based on point-transect surveys. Surveys were conducted three times for each transect or grid to facilitate estimates of occupancy, which rely on an encounter-history matrix derived from repeated visits, rather than a detection function to account for detectability. There was a total of 1,580 point visits (the number of unique points multiplied by the number of visits) on the 34 transects or grids. Of these, 1,161 were point visits in grassland habitats (including 47 point visits in pinyon-juniper woodland habitat) and 419 were point visits in riparian habitats. We recorded a total of 36,695 birds of 217 species on our points. The greatest number of birds were counted at Lake Meredith NRA (n = 6,397), while the smallest number of birds were counted at Lyndon B. Johnson National Historical Park (NHP; n = 2,019). Species richness and community composition varied widely among the parks surveyed. We observed the greatest number of species at Lake Meredith NRA (n = 120) and the fewest at Sand Creek Massacre National Historic Site (NHS; n = 57). The number of birds or species detected is influenced not only by the number of points, but also by the size and diversity of available habitats. Mourning Dove was the most counted species in the SOPN in 2016 (n = 2,242), followed by Western Meadowlark (n = 2,175), Cliff Swallow (n = 1,502), and Red-winged Blackbird (n = 1,068). Eight species, Barn Swallow, Blue Grosbeak, Brown-headed Cowbird, Eurasian Collared-Dove, Lark Sparrow, Mourning Dove, Red-tailed Hawk, and Turkey Vulture, were detected at all 10 parks surveyed. New species, previously unverified for a given park, were recorded during surveys for nine parks (all except Capulin Volcano NM). Overall, the number of new species recorded in 2016 was substantial compared to some previous years.

Landbird monitoring in the Southern Plains Network: 2016 annual report

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