Podilymbus podiceps  

The sight of a Pied-billed Grebe floating on or diving into a body o water surrounded by cattails is a familiar one for North American birders. Even when concealed in emergent vegetation, these grebes can be distinguished by their calls. These grebes are opportunistic feeders, catching fish, frogs and crustaceans in the water, and also picking insects and a variety of other invertebrates from vegetation or even in the air. When on the surface of water, Pied-billed Grebes can escape danger by quietly sinking into the water or crash-diving to go under water. They can remain there with only their eyes and nostrils exposed.  Males defend their breeding territories aggressively, ofter attacking conspecifics and other birds from underwater (Muller and Storer 1999).

DISTRIBUTION. During the 1987-1992 field work seasons of the TBBA project, atlasers found breeding evidence for Pied-billed Grebes in all regions of Texas, with the fewest in the Trans-Pecos, Rolling Plains, South Texas Brush Country and Edwards Plateau. They are most common in the Coastal Prairies and Coastal Sand Plain region (see the region map in Lockwood and Freeman [2004]). In Oklahoma atlasers found only 4 confirmed and 10 probable breeding sites scattered across that state (Jackson 2004).,

Pied-billed Grebes are widespread in North America, Middle America and South America. In North America, the densest breeding occurrs in the waterfowl “factories” of the Dakotas and adjoining Canadian provinces. Northern populations are primarily migratory, moving south after the breeding season to join sedentary populations in the southern United States and Mexico (Howell and Webb 1995, Am. Ornithol. Union 1998, Sauer et al. 2007).

SEASONAL OCCURRENCE. Migratory and wintering Pied-billed Grebes are uncommon to common in Texas from late July to early May when they may be present on both fresh and brackish water. Resident birds breed essentially year-round, but most commonly from March to September, based on egg collection dates from March to August 25 and small young reported from February 22 to January 17 (Oberholser 1974, Muller and Storer 1999, Lockwood and Freeman 2004).

BREEDING HABITAT. Across their range in North America Pied-billed Grebes generally breed in bodies of water, partly open, and edged with aquatic vegetation (Harrison 1979). In Arizona (Wise-Gervais 2005) atlasers found about 80% of breeding records in marshland habitats like those listed by Harrison (1979). In Colorado atlasers found  all records in similar habitats (Potter 1998).

In water at least 30 cm (1 ft) deep both sexes build a floating nest of decaying plant material anchored to or among live or dead vegetation. The shallow depression, slightly above water, has a typical outside diameter of  38 cm (15 in), height above water of 8 cm 3.3 in), inside diameter 12 cm (5 in) and cup depth 5 cm (2 in; Harrison [1979] who provides nest photos).

In the nest the female usually lays 4-8 (range 3-10) smooth pale blue or green eggs at irregular intervals. The eggs, which turn buff or brown during incubation are indistinguishable from those of Horned (Podiceps auritus) and Eared (P. nigricollis) grebes. Incubation, mostly by the female, starts after the first egg is laid and lasts about 23 days. During breaks in incubation, the eggs are covered with wet debris (Harrison 1979, Muller and Storer 1999).

STATUS. Lockwood and Freeman (2004) describe Pied-billed Grebe as a rare to uncommon breeder in Texas with the caveat that in any favorable year the species may be locally common. The TBBA map is generally similar to the distribution of breeding symbols on the map in Oberholser (1974), suggesting no drastic change in breeding range has occurred in recent years. Data from the North American Breeding Bird Survey suggest a +7.8% annual population change for Texas for 1980-2006. These data and the position of this state well within both the breeding and wintering ranges of this species make its future in Texas seem secure.

Literature cited.

American Ornithologists’ Union. 1998. Checklist of North American birds, 7^th ed. Am, Ornithol. Union, Washington, DC.

Harrison, H. H. 1979. A field guide to western birds’ nests. Houghton Mifflin, Boston, MA.

Howell, S. N. G. and S. Webb. 1995. A guide to the birds of Mexico and northern Central America. Oxford University Press, New York.

Jackson, J. A. 2004. Pied-billed Grebe (Podilymbus podiceps). In Oklahoma breeding bird atlas, pp. 20-21 (D. L. Reinking, ed.). University of Oklahoma Press, Norman.Lockwood, M. W. and B. Freeman. 2004. The TOS handbook of Texas birds. Texas A&M University Press, College Station.

Muller, J. M. and R. W. Storer. 1999. Pied-billed Grebe (Podilymbus podiceps). In The birds of North America, No. 410 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.

Oberholser, H. C. 1974. The bird life of Texas. University of Texas Press, Austin.

Potter, K. M. 1998. Pied-billed Grebe (Podilymbus podiceps). In Colorado breeding bird atlas, pp. 40-41 (H. E. Kingery, ed.), Colorado Bird Atlas Partnership, Denver.

Sauer, J. R., J. E. Hines, and J. Fallon. 2007. The North American breeding bird survey, results and analysis 1966-2006. Version 7.23.2007. USGS Patuxent Wildlife Research Center, Laurel MD < http://www.mbr-pwrc.usgs.gov/bbs>

Wise-Gervais, C. 2005. Pied-billed Grebe (Podilymbus podiceps). In Arizona breeding bird atlas. pp. 92-93 (T. E. Corman and C. Wise-Gervais, eds.), University of New Mexico Press, Albuquerque.