Associated Species: Other species that may use habitat in a similar way and/or respond similarly to threats, management, and conservation activities include Flammulated Owl, Olive-sided Flycatcher, Violet-green Swallow, Pygmy Nuthatch, and Western Tanager.

Distribution: Grace's Warblers breed from southwestern Colorado and southern Utah, south through central Arizona, western New Mexico, and into north-central Mexico. Wintering areas extend from northern Mexico to Central America.

Habitat Requirements: Grace's Warblers inhabit open ponderosa pine forests with pines 5 m (16 ft) tall, especially with a shrubby understory, usually Gambel oak.

Ecology: Birds arrive in Colorado in early May and lay eggs in late May and early June; the young fledge by late June and early July. Nearly four decades after Webster (1961) declared this "one of the least known of North American parulids," little new information has been published about its ecology.

Management Issues and Conservation Recommendations: Threats to Grace's Warblers include the loss of mature ponderosa pines due to timber harvest, and the closing of ponderosa stands by dense young trees due to fire suppression. Restore ponderosa pine forests to presettlement conditions of large trees, in clusters, with an open understory of grasses.

Status and Reasons for Concern: Grace's Warblers have a high conservation need locally and throughout their range. A very high proportion (estimated at 30.6%) of their total population occurs within Physiographic Area 87, indicating that this area has high responsibility for their conservation. These warblers are not adequately monitored by the BBS within Physiographic Area 87, and data collected between 1969 and 1996 are too sparse to allow analysis of trends (n = 11 routes). Continent-wide results do not show a statistically significant annual rate of change (P = 0.42; n = 32) between 1966 and 1996, although results for the same period in New Mexico approach statistical significance (P = 0.12; n = 14 routes). This species is monitored by MCB with point transects.

Biological Objective: Maintain or increase the species' distribution and abundance, based upon results of the BBS and MCB monitoring programs.

Selected References: Andrews and Righter 1992, Kingery 1998, Webster 1961.