Populations Of Ground-nesting Birds Research Articles

Use of Predator-Deterrent Fences to Increase Attwater's Prairie-Chicken Nest Success

AbstractWe retrospectively evaluated 20 y of using predator-deterrent fences to mitigate unusually high nest predation for the critically endangered Attwater's prairie-chicken Tympanuchus cupido attwateri at the Attwater Prairie Chicken National Wildlife Refuge. Refuge staff constructed fences of 0.9-m-high, 0.32–0.64-cm mesh hardware cloth, with 15.2-m-long sides, and staked at the bottom to discourage predators from going under the fence. Workers placed fences around nests at a mean of 3.2 d of incubation. Eighty-two percent of fenced nests were successful vs. 12% for unfenced nests. Daily survival rate increased from 0.9159 for unfenced nests in 1997–2011 to 0.9916 for fenced nests during 2000–2019. Fencing did not increase abandonment or reduce the proportion of eggs that hatched in successful nests. After 2012, we reduced fence sides from 15.2 m to 7.6 m in length. Larger and smaller fences were equally effective with respect to daily survival rate and proportion of abandoned nests. The median proportion of eggs that hatched from successful nests was 6% higher for larger fences vs. smaller fences, but this difference was not statistically significant. Predator-deterrent fences substantially increased Attwater's prairie-chicken nesting success in this study, and may represent a viable management strategy for increasing nesting success for other populations of ground-nesting birds with high conservation value.

The new faces of nest predation in agricultural landscapes\u2014a wildlife camera survey with artificial nests

European populations of many ground-nesting farmland birds have declined in recent decades. Increases in predator populations and nest predation may play an important role in this decline, along with habitat loss. However, the role of various predators has often remained unclear. We conducted a study with artificial nests and wildlife cameras (n = 104) in agricultural landscapes during 2015–2016 in South Finland. Our trials formed a 400-m wide gradient from forest to field. The aim of our study was to monitor nest survival and nest predators in a spatial and temporal scale. We tested the effect of distance to the forest and nest visibility to nest predation. During an 8-day period, 39.4% of the artificial nests were predated. Fifty percent of the predators were birds, 40% mammals, and 10% remained unknown. The three dominant predators of our artificial nests were the raccoon dog (Nyctereutes procyonoides) with 11 nests and the hooded crow (Corvus corone cornix) and the magpie (Pica pica) with 10 depredated nests each. Our analysis indicates that avian predators preyed upon nests in open fields further away from the forest edge, whereas mammalian predation concentrated closer to the forest edge. Predation occurred more likely at the beginning of the survey and nest survival increased as days passed. Our study highlights the efficiency of using wildlife camera traps in nest predation studies. We also suggest that the ongoing expansion of alien predators across Europe may have a greater impact on ground-nesting bird populations than previously anticipated.

Absence of effects of predator control on nesting success of Northern Lapwings Vanellus vanellus: implications for conservation

The control of generalist predator populations is increasingly adopted as a management tool to combat declines in ground-nesting bird populations. However, compensatory predation by uncontrolled species frequently occurs, so determining the relative impacts of different predatory species, and hence the relative benefits of their control, can be difficult. Islands, with their reduced faunas, provide natural experimental units for investigating specific predator–prey interactions in detail. We studied Northern Lapwing Vanellus vanellus breeding success on an island where feral Ferrets Mustela furo and Hooded Crows Corvus cornix were subjected to trial control regimes over 2 years. In both years, Lapwing hatching success was >80%, with neither Ferret nor Crow control selected as important predictors. Fledging rates in both years were 0.7 young per pair, despite highly effective predator removal, although Crow control potentially resulted in compensatory predation by Common Ravens C. corax. Neither mustelid nor corvid control produced significant immediate benefits for Lapwings. This suggests that mesopredator release of mustelids in mainland situations is unlikely to be a consistent threat to Lapwing, and provides further evidence that declines in this species are unlikely to be tackled successfully through predator management alone.

Forest composition, leaf litter, and songbird communities in oak- vs. maple-dominated forests in the eastern United States

Within the eastern deciduous forest region, forest composition varies, with some areas dominated by a mix of oaks ( Quercus spp.) and other areas dominated by a mix of sugar maple ( Acer saccharum) and other tree species. Prescribed fire is being used on an experimental basis to assess its effectiveness in restoring and maintaining oak-dominated forests. Maple-dominated forests are susceptible to invasion by non-native earthworms, such as Lumbricus terrestris, given the palatability of leaf litter and suitable soil conditions, especially in northern parts of the region. What are the implications of this variation on leaf litter availability and habitat for ground-nesting songbirds? We investigated this question by comparing forest composition, leaf litter, and songbird communities in maple-dominated forests in west-central Indiana and oak-dominated forests, recently burned and unburned, in southeastern Ohio. We also assessed abundance of earthworms and decomposition rates of different types of leaves in the maple-dominated forests in Indiana. Leaf litter and ground-nesting bird species were abundant in unburned oak-dominated forests, but were absent or nearly absent in recently burned oak-dominated forests and in maple-dominated forests. The lack of leaf litter and absence of ground-nesting bird species in maple-dominated forests may be due to the combination of abundant non-native earthworms, alkaline and calcium-rich soils, palatable leaves, and rapid leaf litter decomposition rates. Effects of burning on leaf litter and ground-nesting bird species in oak-dominated forests are probably temporary, as long as prescribed fires are not applied on a frequent or widespread basis. Our study is the first one to show a correlation between forest composition, leaf litter availability, earthworm abundance, and songbird populations. Many researchers are investigating effects of non-native earthworm invasions on ecosystem properties in eastern deciduous forests. We recommend that researchers should also monitor songbird populations to assess whether declines in ground-nesting bird populations are occurring in response to these changes.