DOI: 10.5061/dryad.f4qrfj70b
title: Data for: Evaluating Golden-winged Warbler use of alder and aspen communities managed with shearing in the western Great Lakes

description: Best management practices are often written by researchers to guide land
 managers and landowners in the creation of habitat for wildlife species of
 interest. These documents are based on research evaluating the habitat
 needs of a species, but also describe tools and strategies managers can
 implement to create or restore desired conditions. Shrub and sapling
 shearing is a management practice often used to improve habitat for
 early-successional species, yet little monitoring or research has focused
 on wildlife response to shearing. The goal of this research was to
 formally evaluate the effect of shrub and sapling shearing as a best
 management strategy for Golden-winged Warbler (Vermivora chrysoptera)
 conservation at a regional scale. Specifically, we surveyed for male
 Golden-winged Warblers during the breeding season in sheared sites and
 untreated reference sites across portions of the western Great Lakes to
 assess the effects of 1) management status (i.e., sheared aspen or alder
 vs un-treated sites), and 2) the patch-level vegetation characteristics on
 male abundance. We found that male Golden-winged Warbler abundance was
 twice as high in sheared sites than in mature reference sites and peaked
 when sapling cover was ~40%. Male abundance was also negatively associated
 with percent cover of forbs and non-vegetated ground. These findings
 highlight the importance of patch-level heterogeneity when implementing
 shearing treatments for Golden-winged Warblers, and demonstrate the
 potential need for pre-treatment site assessments to help focus
 conservation efforts for this species. Ultimately, our results support the
 use of a site-specific, nuanced approach to shearing implementation to
 maximize cost efficiency and desired species outcomes.
description: We counted male Golden-winged Warblers at each site using a
 passive 10-minute point count between May 25 and July 2 each year
 (2012–2013, 2015–2018; n=1,222 point counts conducted). Points were
 visited once, annually, in 2012–2013 (n=13 points per year) and twice
 annually in 2015–2018 (n=68–217 points per year), and surveys were
 conducted in favorable weather conditions (no heavy precipitation, wind,
 or fog) and between 30 minutes before sunrise and five hours after
 sunrise. Golden-winged Warbler count data were truncated to include only
 males detected within 100 m, which eliminated ~3% of detections. Prior to
 the start of each point count, we recorded survey metadata including
 weather conditions (precipitation type, Beaufort wind index, percent cloud
 cover [0- 175 100%] rounded to the nearest 25%), point location, date,
 survey start time, and observer identity. Beaufort wind categories 0–2
 were combined into a low wind index category and Beaufort categories 3–5
 were combined to make a high wind index category for modeling. All
 visually and aurally detected Golden-winged Warblers were recorded as well
 as detection type (visual, audio, both), sex, and distance (estimated to
 the nearest 5m). We collected vegetation data at each location where
 Golden-winged Warblers were surveyed during 2015–2018 to examine
 relationships between male Golden-winged Warbler abundance and patch-level
 habitat characteristics. We sampled vegetation annually each field season
 from early July to August, except at reference sites which we only
 surveyed once under the assumption that the vegetation structure at these
 sites remained consistent throughout the duration of our sampling. We
 quantified vegetation characteristics along three 100-meter transects
 radiating from each point count location at 0, 120, and 240-degree
 azimuths. Every ten meters along each transect (n=30 locations/transect),
 we used an ocular tube (James and Shugart 1970) to record the presence or
 absence of vegetation strata: bare ground, leaf litter, graminoids (grass
 and sedge), forbs, ferns, Rubus, shrubs, saplings, and canopy trees. Leaf
 litter and bare ground strata were combined into non-vegetated strata for
 modeling. At the same 30 locations, we recorded the presence or absence of
 woody regeneration (shrubs and saplings) in four categories [none, small
 (0–1 m tall), medium (&gt; 1–2 m tall), and large (&gt; 2 m tall)]
 within a 1-meter radius area, for a site-level percent 199 occurrence
 value of each category. Although we aimed for 30 locations of sampling at
 each site, we truncated transect lengths when they extended beyond the
 boundary of a treatment footprint thus resulting in fewer than 30 subplots
 for some sites with irregular boundaries or a small footprint. We
 estimated patch-level cover and occurrence values for each vegetation
 component by dividing the number of subplots where a component was present
 by the total number of subplots sampled. Percent occurrence (measured at 1
 m radius woody regeneration plots) differs from the commonly used percent
 cover metric (which was used for other metrics in this study) because it
 does not take the density of each habitat element into account, only its
 presence or absence throughout the site.