Open Space Advisory Board Agenda and Packet 2017 08 09

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1. Introduction The City of Louisville, Colorado Open Space Division contracted Wildlife Specialties LLC to conduct avian surveys at three Open Space Properties: Coyote Run, Daughenbaugh, and Warembourg (Figure 1) in the late spring/early summer of 2017. All three Open Spaces surveyed are surrounded on all sides by residential and commercial development. Of the three, Coyote Run is the only property that has wildlife habitat connectivity to other Open Space properties. All of the properties are used heavily for recreation and exercise with almost all of the activity occurring on the designated trails. 2. Methods The City of Louisville Request for Proposals for conducting the surveys called for the number and type of avian survey used at each Open Space. Two survey methods were used in the 2017 surveys: point counts (n = 1) and line transects (n = 6). Point count strengths and weaknesses are as follows: Time is available to spot and identify shy and/or hard to observe species. Adaptable to species specific surveys (e.g. Southwestern Willow Flycatchers) and habitats (more dense and diverse habitats). Double counting (counting the same bird twice) is a concern (a bird could be detected visually or aurally in one location and move, undetected, to a different location where it is then again unknowingly detected and recorded as a new detection). Time is "lost" while moving between point count stations. Line transect have their strengths and weaknesses as well: More area is surveyed more quickly as the surveyor slowly walks each transect. Adaptable to species and habitats (better for more open habitats). Double counting is a minor problem. Adequate for habitat studies. Two avian line transect surveys were conducted on each of the Open Space properties. The main assumption of line transect surveys is that detectability remains constant (Bibby et al. 2000). Line transects are often done in large open areas with little cover. This is preferred over point counts in open areas because more birds are observed over the same unit of time while moving. Transect location is usually based on access and are often systematically located to provide a representative sample of the survey area. Prior to the finalization of each transect used at the three Open Space properties, transects were laid out in GIS and the locations were presented to the City of Louisville for concurrence that the selected locations provided the best representation of each Open Space (Figure 2). Preselecting transect locations allowed for positioning the transects to intersect with as many habitat types as possible while maintaining sufficient distance between transects so there would be less chance of double counting birds. Each transect was slowly walked with the surveyor being observant of avian activity within 150 meters (parallel) to each transect. Detections beyond that distance were not recorded. When a bird was observed ahead of the surveyor the distance was estimated from the transect, not from the observer. All distance was measured using a Leupold© LASER range finder. Only one survey was completed at each of the transect locations. Distance sampling was incorporated into the data collections because it is an efficient way to estimate bird density and can provide a measure of bird `detectability'. However, good density estimate require 60-80 bird detections for line transects and 80-100 detections for point transects. 3 10