Wildfire perimeters on US bird survey routes in 2000-2021 were followed by more woodpeckers and fewer canopy gleaners; total bird counts and richness did not change clearly

We tested if large wildfires change breeding bird groups on North American Breeding Bird Survey (BBS) routes in the contiguous United States. We put MTBS fire perimeters (1984-2026) on BBS route lines and approximate stop locations, and used BBS 50-stop counts from 1997-2025. Design A compared 106 routes with at least 10% of a 400 m route buffer inside one year's wildfire perimeters (2000-2021) with 1,449 unburned routes in the same Bird Conservation Region. It used route-by-observer and stack-year fixed effects. Design B compared burned and unburned stops on the same survey runs on 80 of these routes. We fixed the bird groups by family before we looked at outcomes. After fire, woodpecker counts increased (A: +0.108 +/- 0.040 log units, placebo p = 0.010; B: +0.062 +/- 0.018). Canopy foliage and bark gleaner counts decreased (A: -0.121 +/- 0.039, placebo p = 0.005; B: -0.069 +/- 0.022). Both effects were larger at higher burn fractions and had the same sign in the West and East, in 2000-2010 and 2011-2021 fires, and in both designs. They were clear in the Pacific states and weak in the Interior West. Total counts, species richness and open-forest insectivores did not change clearly. In design A, a linear trend term absorbed most of the canopy decline. The within-route design was flat before the fire and kept the decline (-0.095 +/- 0.030 with a trend term). Observer turnover, survey date and run quality did not change clearly after fire. Limitations: the route lines are from 1966-1998, the stop locations are approximate, perimeters do not show burn severity, the routes are roadside, detection can change in open habitat, and most events are in the western US. Ten prescribed-fire events were too few to test.

wildfire · Breeding Bird Survey · MTBS · woodpeckers · canopy gleaners · before-after-control-impact · stacked event study · observer effects · community composition · disturbance ecology · fire ecology · placebo inference