Estimating offsets for avian displacement effects of anthropogenic impacts

Abstract

Biodiversity offsetting, or compensatory mitigation, is increasingly being used in temperate grassland ecosystems to compensate for unavoidable environmental damage from anthropogenic developments such as transportation infrastructure, urbanization, and energy development. Pursuit of energy independence in the United States will expand domestic energy production. Concurrent with this increased growth is increased disruption to wildlife habitats, including avian displacement from suitable breeding habitat. Recent studies at energy‐extraction and energy‐generation facilities have provided evidence for behavioral avoidance and thus reduced use of habitat by breeding waterfowl and grassland birds in the vicinity of energy infrastructure. To quantify and compensate for this loss in value of avian breeding habitat, it is necessary to determine a biologically based currency so that the sufficiency of offsets in terms of biological equivalent value can be obtained. We describe a method for quantifying the amount of habitat needed to provide equivalent biological value for avifauna displaced by energy and transportation infrastructure, based on the ability to define five metrics: impact distance, impact area, pre‐impact density, percent displacement, and offset density. We calculate percent displacement values for breeding waterfowl and grassland birds and demonstrate the applicability of our avian‐impact offset method using examples for wind and oil infrastructure. We also apply our method to an example in which the biological value of the offset habitat is similar to the impacted habitat, based on similarity in habitat type (e.g., native prairie), geographical location, land use, and landscape composition, as well as to an example in which the biological value of the offset habitat is dissimilar to the impacted habitat. We provide a worksheet that informs potential users how to apply our method to their specific developments and a framework for developing decision‐support tools aimed at achieving landscape‐level conservation goals.

Bird Displacement by Wind Turbines: Assessing Current Knowledge and Recommendations for Future Studies

“…(5) In gradient study designs, as much as possible, estimate the maximum influence distance, rather than simply reporting the significance of the variable 'distance to turbine' effect on abundance or space use. The estimate of distance-based threshold responses to wind farms is very important to better understand displacement impacts but also to guide policy and EIA decisions, such as the establishment of protected areas and management actions for species of concern [102].…”

“…Future studies will improve our knowledge on the topic and will be essential to guide wind energy development on a large scale, but also at a project level. To date, mitigation measures aiming at bird displacement include avoiding areas with sensitive species to this effect and the implementation of compensatory programs that include habitat management actions [102].…”

Upland burning and grazing as strategies to offset climate-change effects on wetlands

“…Impacts to breeding ducks in the sub-region of the PPR that we studied could be much greater than areas with lower wetland densities. On average it is estimated that a comparable wetland to T8 in the same Waterfowl Breeding Population and Habitat Survey stratum contains 6-8 pairs of breeding ducks (Shaffer et al 2019). This means that for every wetland not ponded in stratum 46 there could be displacement of 6-8 breeding duck pairs.…”

A framework for evaluating the implications of assumptions in broad conservation strategies

“…We found case examples from North American wildlife management and theoretical evidence that underpin the "more acres, more animals" assumption. As wildlife declines have been increasingly linked to loss of habitat (Shaffer et al, 2019), there is a basis for the expectation that private lands conservation program enrollment could reverse observed wildlife population declines by reducing decline drivers. For example, dramatic declines in grassland-dependent birds resulting from westward agricultural expansion (Reynolds, 2004) were, in some cases, reversed as a result of agricultural private lands conservation programs implemented in the post-WWII era (Heard et al, 2000).…”