| The use of surrogate species, in which a focal species is used to represent other species of interest, is a common practice in conservation. However, the validity of this concept has been rarely tested. This 1996--1999 study assessed the utility of the Cerulean Warbler (Dendroica cerulea ) as a surrogate species in eastern Ontario and was undertaken at the Queen's University Biological Station (44°34'N, 76°20'W).; A documentation of Cerulean Warbler habitat requirements, achieved while avoiding inconsistencies uncovered in a review of the avian habitat literature, indicated that Cerulean Warblers have potential as indicators of the deciduous forest health as Cerulean Warbler reproductive success appears to be dependent on complex forest canopies (based on analyses of 115 territories and 95 nests). A January 1998 ice storm drastically altered canopy structure and subsequent nesting success dropped to 8.9% (n = 45 nests) from a pre-storm average of 75.7% (n = 37, 1994--7). The decrease may be related to damage-induced reductions in foliage arthropod populations, indicating potential utility of the Cerulean Warblers as indicators of insect populations. Interestingly, 1999 nesting success increased (36.4%, n = 30) as did average territory size (pre-storm mean---0.69ha, 1998---0.74ha, 1999---1.17ha). This increase was accompanied by a significant shift in 1999 nest-site selection patterns towards locations higher in larger trees with more foliage cover. The utility of Cerulean Warblers as a population or health indicator was compromised by the plasticity in their habitat affinities that may render this species resilient to certain habitat disturbances.; The results of extensive survey indicated that, while Cerulean Warblers were the fourth most common warbler in the study area, they have no potential as indicators of high avian biodiversity. However, their broad distribution did confer the Cerulean Warbler potential as an umbrella species. The spatial distribution of this species matched those of other mature forest species implying that Cerulean Warbler habitat management would provide for other species. Finally, Cerulean Warblers could be used as a flagship species by focusing efforts aimed at the preservation of mature, deciduous forest and the conservation of other species that require similar habitats. |
