Forest Management, Barred Owls, and Wildfire in Northern Spotted Owl Territories

Abstract

The Northern Spotted Owl (Strix occidentalis caurina) (NSO) was listed as federally threatened in 1992 due to widespread logging of its old-growth forest habitat. The NSO recovery plan in 2011 elevated competition with Barred Owls (Strix varia) (BO) and wildfires as primary NSO threats based partly on the assumption that severely burned forests were no longer NSO nesting and roosting habitat. We quantified amount of logging before and/or after wildfire and opportunistic detections of BOs within two home range scales (0.8 and 2.09 km) at 105 NSO sites that experienced severe wildfire from 2000–2017. Logging affected 87% of severely burned NSO sites, with BO recorded at 22% of burned-and-logged sites. Most (60%) severely burned NSO sites had evidence of logging both before and after fires while only 12% of severely burned sites had no logging or BO detections, indicating rarity of NSO territories subjected to severe fire without the compounding stressors of logging and invasive BOs. We recommend changes to NSO habitat modeling that assume nesting and roosting habitat is no longer viable if severely burned, and to the US Fish and Wildlife Service’s practice of granting incidental take permits for NSOs in logging operations within severely burned owl sites.

Ten Principles for Bird-Friendly Forestry: Conservation Approaches in Natural Forests Used for Timber Production

“…American migratory species that are negatively affected by logging include the Eastern Whip-poor-will (Antrostomus vociferus), Bicknell's Thrush (Catharus bicknelli), Cerulean Warbler (Setophaga cerulea-72%), Canada Warbler (Cardellina canadensis-62%) Wilson's Warbler (Cardellina pusilla-57%), Blackpoll Warbler (Setophaga striata-92%), and Purple Finch (Haemorhous purpureus-47%), which have declined between 47-92% since 1970 [66,69,71,75]. Particularly vulnerable to negative impacts of logging operations are avian guilds and species that rely on large, mature trees for breeding, notably woodpeckers and other cavity-nesting birds [2,[4][5][6][7]21,76] as well as raptors and other canopy-nesting birds [2,4,7,8,[77][78][79][80]. Many cavity nesters use snags, including dying, dead, and rotten trees, for nesting and foraging, and logging and snag removal can thus reduce or eliminate nesting and foraging opportunities [21,76,81,82].…”

“…Logging has been implicated in the declines of the Middle Spotted Woodpecker (Dendrocoptes medius) in Sweden [83] and the Ivory-billed Woodpecker (Campephilus principalis) [84], Red-cockaded Woodpecker (Picoides borealis) [85], and Red-headed woodpecker (Melanerpes erythrocephalus) [86] in the United States. Forest-breeding raptors and other predatory birds whose declines are associated with logging include the Black Stork (Ciconia nigra) in the Baltic countries of Estonia, Lithuania, and Latvia [78,79] Figure 2 and the Northern Goshawk (Accipiter gentilis) [77] and Northern Spotted Owl (Strix occidentalis caurina) [80] in the northwestern United States. In the case of Black Storks, reproductive success is tied to the availability of mature trees, which have increasingly been eliminated since the intensification of forestry in the Baltic countries starting in the mid-1990s [78,79] Figure 3.…”

“…In addition to cavity-and canopy-nesting birds, ground-nesting and insectivorous birds in general appear to be particularly vulnerable to the negative effects of logging in mature forests [2,4,[6][7][8][9]. Particularly vulnerable to negative impacts of logging operations are avian guilds and species that rely on large, mature trees for breeding, notably woodpeckers and other cavitynesting birds [2,[4][5][6][7]21,76] as well as raptors and other canopy-nesting birds [2,4,7,8,[77][78][79][80]. Many cavity nesters use snags, including dying, dead, and rotten trees, for nesting and foraging, and logging and snag removal can thus reduce or eliminate nesting and foraging opportunities [21,76,81,82].…”

“…Whereas natural disturbances such as forest fires are typically followed by ecological succession without human disturbance, logging operations may be followed by a high intensity of human activities, with corresponding detrimental impacts on birds [49,80,96]. Hunting, recreation, and other human activities following logging operations, may drive declines in bird populations that could otherwise recover over time [49].…”