Veery Habitat Model
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Veery, Catharus fuscescens
Use of Study Area Resources:
Reproduction. Veeries breed across southern Canada and the upper Midwest through New England, southward into the Appalachians. They winter in northern South America (Moskoff 1995).
Cover. The veery breeds in damp, deciduous or mixed forests (Kendeigh 1948, Dilger 1956, Morse 1971, Paszkowski 1984). Riparian cover types are preferred in many regions of the United States (Tubbs 1980). Plants characteristic of early successional and/or wetter areas are significantly more common in veery territories than in territories of other thrushes (Bertin 1977, Paszkowski 1984).
Area. In Illinois veeries breed in forest patches > 27 ha (Herkert 1995); 90% of the occurrences were in patches > 100 ha. In Wisconsin 88% of occurrences were in patches > 100 ha (Temple 1986). Robbins et al. (1989) observed veeries in patches as small as 9 ha, but found maximum likelihood of occurrence in patches between 250 and 3000 ha.
Edge. Fragmentation increases access by brown-headed cowbirds (Molothrus ater) to forest interiors. As a result, cowbird parasitism may reduce veery reproductive success (Moskoff 1995). Temple (1986) found that a "core area" model, discounting the value of habitat within 100 m of the forest edge, was more accurate for veery than a "total area" model. This indicates that forest interiors are more valuable to veeries than forest edge.
Moisture. Robbins et al. (1989) found a significant association between veery occurrences and moisture gradient. Territories are typically located near densely vegetated streams or swamps (Bertin 1977, Holmes and Robinson 1988, Moskoff 1995). Bertin (1977) postulated that moisture regime (cooler microclimate) may be more important than shrub cover and proximity to water in habitat selection.
Habitat was based on vegetative cover (see table, below), patch size, distance from edge, and moisture regime. Patches of suitable forest types of 300 ha or larger were regarded as optimal (1.0); 100 to 300 ha was scored 0.7; 10 to 100 ha was scored 0.3; any smaller = 0.
The edges of forested patches were regarded as less valuable than forest interiors. Scores for habitat within 60 m of non-forested covers were multiplied by 0.5.
Hydric soils were identified using digital USDA/NRCS soils maps. Sites either having hydric soils, located within 60 m of ponds or streams, or mapped as shrub or forested wetlands were regarded as having suitable moisture levels. Drier sites were regarded as less suitable, and scores of such areas were multiplied by 0.5.
|Cover Types||Cover Suitability
(0 - 1 scale)
|Upland deciduous forest||1.0|
|Upland coniferous forest|
|Upland mixed forest||1.0|
|PEM, L2EM||Lake/pond, emergent vegetation|
|PFOcon||Palustrine forest, conifer|
|PFOdec||Palustrine forest, deciduous||1.0|
|PSSdec||Palustrine scrub shrub, deciduous||1.0*|
|PSScon||Palustrine scrub shrub, conifer|
|PAB, L2AB||Lake/pond, aquatic vegetation|
|L1UB, PUB||Lake/pond, unconsolidated bottom|
|L2US||Lake, unconsolidated shore|
|L2RS||Lake, rocky shore|
|R1UB||Riverine subtidal unconsolidated|
|E1AB||Estuarine subtidal vegetated|
|E1UB||Estuarine subtidal unconsolidated bottom|
|E2AB||Estuarine intertidal algae|
|E2EM||Estuarine intertidal emergent|
|E2RS, R1RS||Estuarine, tidal river rocky shore|
|E2SS||Estuarine intertidal shrub|
|E2US, R1US||Estuarine, riverine intertidal unconsolidated shore|
|M1AB||Marine subtidal vegetated|
|M1UB||Marine subtidal unconsolidated bottom|
|M2AB||Marine intertidal algae|
|M2RS||Marine intertidal rocky shore|
|M2US||Marine intertidal unconsolidated shore|
|NOTES||*Score if adjacent to forested cover|
Overall habitat suitability was calculated as the product of the cover, area, edge, and moisture scores. Comparison of this product with veery occurrences from the 1990 Breeding Bird Survey led us to discard areas that were relatively unsuitable (overall product < 0.5) . The final model then was rescaled to a 0 - 1.0 basis
Model Testing: The veery occurrences along Breeding Bird Survey routes throughout the study area were used to test the final habitat map. We compared the presence of habitat near a random set of 797 upland points to that for Breeding Bird Survey stops at which veeries were observed in 1997 or 1998. Of the 812 sites with birds, 703 had mapped habitat, while 657 sites out of the 797 randomly distributed sites had habitat. The Chi-square was significant, indicating that the overall model does indicate localities useful to veeries. When just the higher scored habitats were tested (0.7,1.0 habitat suitability levels), the level of significance increased, respectively. This stronger association for the higher scored habitats indicating that the relative habitat scoring was valid.
Bertin, R. I. 1977. Breeding habitats of the Wood Thrush and Veery. Condor 79:303-311.
Dilger, W.C. 1956. Adaptive modifications and ecological isolating mechanisms in the thrush genera Catharus and Hylocichla. Wilson Bull. 68:171-199.
Herkert, J.R. 1995. Status and habitat area requirements of the veery in Illinois. The Auk 112(3):794-797.
Holmes, R.T. and S. K. Robinson. 1988. Spatial patterns, foraging tactics, and diets of ground-foraging birds in a northern hardwood forest. Wilson Bull. 100:377-394.
Kendeigh, S.C. 1948. Bird populations and biotic communities in northern lower Michigan. Ecology 29:101-114.
Paszkowski, C.A. 1984. Macrohabitat use, microhabitat use, and foraging behavior of the Hermit Thrush and Veery in a northern Wisconsin forest. Wilson Bull. 96(2):286-292.
Morse, D. H. 1971. Effects of the arrival of a new species upon habitat utilization by two forest thrushes in Maine. Wilson Bull. 83:57-65.
Moskoff, W. 1995. Veery (Catharus fuscescens). In The Birds of North America, No. 142 (A. Poole and F. Gill, eds.). The Academy of Natural Sciences, Philadelphia, and The American Ornithologists' Union, Washington, D.C.
Robbins, C.R., D.K. Dawson and B.A. Dowell. 1989. Habitat area requirements of breeding forest birds of the middle Atlantic states. Wildl. Monogr. 103:1-34.
Temple, S.A. 1986. Predicting impacts of habitat fragmentation on forest birds: a comparison of two models. Pages 301-304 in J. Verner, M.L. Morrison, and C.J. Ralph (eds.) Wildlife 2000: Modeling Habitat Relationships of Terrestrial Vertebrates. Univ. Wisconsin Press, Madison, WI.
Tubbs, A.A. 1980. Riparian bird communities of the Great Plains. Pp. 419-433 in Proceedings of the workshop: management of western forests and grasslands for nongame birds (R. M. DeGraaf and K. E. Evans, compilers). USDA For. Serv. Gen.