Teresa Lorenz

The role of wood hardness in limiting nest site selection in avian cavity excavators

Woodpeckers and other primary cavity excavators (PCEs) are important worldwide for excavating cavities in trees, and a large number of studies have examined their nesting preferences. However, quantitative measures of wood hardness have been omitted from most studies, and ecologists have focused on the effects of external tree- and habitat-level features on nesting. Moreover, information is lacking on the role of wood hardness in limiting nesting opportunities for this important guild. Here, we used an information theoretic approach to examine the role of wood hardness in multi-scale nest site selection and in limiting nesting opportunities for six species of North American PCEs. We found that interior wood hardness at nests (n = 259) differed from that at random sites, and all six species of PCE had nests with significantly softer interior wood than random trees (F1,517 = 106.15, P < 0.0001). Accordingly, interior wood hardness was the most influential factor in our models of nest site selection at both spatial scales that we examined: in the selection of trees within territories and in the selection of nest locations on trees. Moreover, regardless of hypothesized excavation abilities, all the species in our study appeared constrained by interior wood hardness, and only 4-14% of random sites were actually suitable for nesting. Our findings suggest that past studies that did not measure wood hardness counted many sites as available to PCEs when they were actually unsuitable, potentially biasing results. Moreover, by not accounting for nest site limitations in PCEs, managers may overestimate the amount of suitable habitat. We therefore urge ecologists to incorporate quantitative measures of wood hardness into PCE nest site selection studies, and to consider the limitations faced by avian cavity excavators in forest management decisions.

Conspecifics Take Over Black-Backed Woodpecker Nest Following Removal of Resident Pair

Abstract On 16 April 2016, a nesting pair of Black-backed Woodpeckers (Picoides arcticus) were illegally killed by a poacher near Rimrock Lake, Washington. We captured the incident on camera and were surprised to observe a female Black-backed Woodpecker visit the partially excavated nest cavity a mere 3 h after the “removal” of the breeding pair (and presumed territory holders). Within 72 h, a male and female were both observed at the abandoned nest and began excavating the partially completed cavity. The intruding pair successfully fledged 2 young from this nest on 10 June 2016. To our knowledge, this is the 1st reported case of a pair of Black-backed Woodpeckers taking over excavation duties at a cavity started by another pair in the same breeding season. While formal studies are needed, this incident suggests conspecific attraction may be used for territory settlement in Black-backed Woodpeckers.

Tag-Team Takeover: Usurpation of Woodpecker Nests by Western Bluebirds

Figure 4: Sequence of interactions between Western Bluebirds and Hairy Woodpeckers at the Hause Creek Nest. Each video file is approximately two hours long and in sequential, although not continuous, order. Figure 2: Data combined from both nests. Only includes interactions against woodpecker species. Bluebird nest box Brown Creeper Conclusion • These bluebird nest attacks were different from typical bird nest defense in that both sexes of the Western Bluebird attacked woodpeckers.

Incorporating Shrub and Snag Specific LiDAR Data into GAP Wildlife Models

Abstract The U.S. Geological Survey’s Gap Analysis Program (hereafter, GAP) is a nationally based program that uses land cover, vertebrate distributions, and land ownership to identify locations where gaps in conservation coverage exist, and GAP products are commonly used by government agencies, nongovernmental organizations, and private citizens. The GAP land-cover designations are based on satellite-derived data, and although these data are widely available, these data do not capture the 3-dimensional vegetation architecture that may be important in describing vertebrate distributions. To date, no studies have examined how the inclusion of snag- or shrub-specific Light Detection and Ranging (LiDAR) data might influence GAP model performance. The objectives of this paper were 1) to assess the performance of the National GAP models and Northwest GAP models with independently collected field data, and 2) to assess whether the inclusion of 3-dimensional vegetation data from LiDAR improved the performance of...