Prairie Warbler

(Dendroica discolor)

 

By:       Jeremy Poirier, Wildlife Program Manager, International Paper Company and

            Mark Johns, NC PIF Coordinator, NC Wildlife Resources Commission

 

 


Photo by: Jeremy Poirier

 

Not a bird of open prairies as the name suggests, the Prairie Warbler breeds in open, sun filled habitats with shrubby vegetation throughout the coastal plain and piedmont regions of North Carolina.  It is less numerous in the mountain region of the state at lower elevations. The Prairie Warbler is more often heard than seen and their distinctive, drawn-out buzzy ascending song can be heard late into the summer.

 

 Description

 

Predominantly a yellow colored bird with vivid black streaking on the flanks and olive/chestnut markings (most noticeable in males) on the back, it is small headed and long-tailed. Adult male Prairie Warblers also possess a distinctive a black colored half-circle below the eye. Adults are approximately 4.5 - 4.75 inches long and are often seen pumping their tales. Adult females are similar in coloration to males, only paler.  First winter females are noticeable less vivid in color and lack black side streaking and markings on the face.

 

Voice

 

The Prairie Warbler song is a buzzy sounding “zee-zee-zee-zee” that rises steadily in pitch.  It may be a fast or slow. It has been likened to sounding like a helicopter taking off. The call note is a rather musical “chip”.

 

 

 

 

Range

 

Prairie Warblers breed in southeastern and central-eastern United States and winter in South Florida, the West Indies, and coastal Central America. In North Carolina, the Prairie Warbler is most commonly found in the Coastal Plain and less common west of the Piedmont. In North Carolina they start showing up in early April and most depart for wintering areas by mid to late October. Occasional individuals linger along the coast in winter.

 

Habitat and Habits

 

The Prairie Warbler is an early successional bird species that depends (foraging, nesting, etc.) on large patches (20+ acres) of disturbed habitat. More specifically, they require a specific type of early successional habitat collectively referred to as “shrub/scrub” habitat. Examples include overgrown fields with scattered shrubs, utility right-of-ways, thickets, second-growth clearings and young pine plantations. They often breed in loose colonies, with site selection and nest construction conducted by the female. Their open cup nest is constructed low to the ground (mainly 2-10 feet high) in a shrub or small tree and lined with animal hair and/or plant material. Females usually lay between 3-5 eggs and incubation time is approximately 12-13 days, with the young remaining in the nest another 8-10 days. Fledglings are usually independent from parental feeding by day 50 and Prairie Warblers can have two broods per season.

 

Conservation Status

 

It is well documented that early successional birds have experienced some of the most rapid population declines over the last 50 years in eastern North America.  According to Breeding Bird Survey (BBS) trends, the Prairie Warbler is no exception. Loss of suitable sized patches of nesting and wintering habitats, development and agriculture, nest parasitism by Brown-headed Cowbirds and nest predation and hazards during migration are all threats to the long-term viability of the species. However, recent BBS surveys conducted on industrial forestlands throughout the coastal plain of North Carolina show significant numbers of Prairie Warblers nesting in young loblolly pine plantations. For example, the number of Prairie Warblers recorded over the last 3 years on International Paper’s BBS in routes in NC (located in Hertford and Brunswick counties), were 10 times greater than the national average. These data suggest that industrial forestlands can play a key conservation role for the species, most likely due to the large patches of suitable habitat over thousands of acres.

 

Management Recommendations

 

Favorable Prairie Warbler habitat declines as forests mature and the canopy closes. Forest management techniques such as timber harvest, mowing, and/or frequent prescribed fire (3-5 year cycles) in older stands, “reverse” natural forest succession and benefit Prairie Warblers. Furthermore, even aged forest management (e.g., clear cutting, seed tree cut, shelterwood cut) will create larger areas of early successional habitat patches as compared to uneven-aged management systems (e.g., individual tree selection). In general, after harvest, birds associated with shrub/scrub habitat begin to utilize these areas due to the reestablishing vegetative ground cover. It is well documented that the number of bird species increases dramatically 3-4 years post harvest. The key is to get that post harvest vegetative (trees and associated forbs, shrubs, and grasses) established as quickly as possible.

 


*      Although most bird species will re-nest if disturbed during the breeding season, spring and summer (April-July) site preparation activities (herbicide application, burning, mechanical work, etc) may negatively affect ground and shrub nesting birds.

 

*      The use of herbicides is a common silvicultural practice used by land managers to help regenerate planted forest and manage wildlife. There are several management tools that minimize the potential impacts of herbicides on wildlife habitat including bird species like Prairie Warblers:

 

 

o         Unless critical to reforestation objectives, avoid herbicides that target plants that are highly utilized by birds such as legumes and blackberries.  Imazapyr (Arsenal/Chopper[1]) is a good example of a selective herbicide that is highly effective against woody species except pine but not against highly-utilized wildlife plants such as dewberry, blackberry, and legumes. 

[1] Trademark of American Cyanamid

o       Avoid tank mixes

o       Favor banded (usually done with a backpack crew) vs. broadcast applications (via helicopter)

o       Leave portions of the stands untreated which will provide potential nesting habitat and stagger herbicide treatments 

o       If possible, avoid 2nd year herbaceous treatments

 

*      Leaving unmerchantable trees and “whips” standing during a timber harvest will provide future perches that early successional birds, like Prairie Warblers, will be able to utilize. These perches can be very important for singing males.


*      Diversify the harvest area by leaving small patches of undisturbed “scrubby” habitat along roads and ditches and scattered throughout the site if possible

 

 

Scientific Literature on Prairie Warblers, other early successional birds and information on management for early successional birds

 

Annand, E. and F. Thompson, III. 1997. Forest bird response to regeneration practices in central hardwood forests. Journal of Wildlife Management. 61: 159-171.

 

Askins, R. 2001. Sustaining biological diversity in early successional communities: the challenge of managing unpopular habitats.  Wild. Soc. Bull. 29: 407-412.

 

Askins, R. 1998. Restoring forest disturbances to sustain populations of shrub land birds.  Restoration and Management Notes. 16: 166-173.

 

Brawn, J., S. Robinson, and F. Thompson III. 2001. The role of disturbance in the ecology and conservation of birds.  Annu. Rev. Ecol. Syst. 32: 251-276.

 

Conner, R.N. and C.S. Adkisson. 1975. Effects of clearcutting on the diversity of breeding birds. Journal of Forestry (783).

 

Easton, W.E. and K. Martin. 2002. Effects of thinning and herbicide treatments on nest-site selection by songbirds in young managed forests. The Auk 119(3):685-694.

 

Hunter, W.C., D.A. Buehler, R.A. Canterbury, J.C. Confer and P.B. Hamel. 2001. Conservation of disturbance-dependent birds in eastern North America. Wild. Soc. Bull. 29(2):440-455.

 

Krementz, D.G. and J.S. Christie. 2000. Clearcut stand size and shrub-successional bird assemblages. The Auk 117(4):913-924.

 

King, D.I., R.M. Degraaf and C.R. Griffin. 2001. Productivity of early successional shrubland birds in clearcuts and groupcuts in an eastern deciduous forest. Journal of Wildlife Management 65(2):345-350.

 

Lorimer, C. 2001. Historical and ecological roles of disturbance in eastern North American forests: 9,000 years of change. Wild. Soc. Bull. 29: 425-439.

 

Noble, R.E., R.B. Hamilton and W.C. McComb. 1980. Some effects of forestry on nongame birds. Annual Forestry Symposium. Louisiana State University, Baton Rouge.

 

Robinson, W. and S. Robinson. 1999. Effects of selective logging on forest bird populations in a fragmented landscape. Conservation Biology 13: 58-66.

 

Rodewald, P.G. and M.C. Brittingham. 2004. Stopover habitats of landbirds during fall: use of edge-dominated and early-successional forests. The Auk 121(4):1040-1055.

 

Santillo, D.J., P.W. Brown and D.M. Leslie, Jr. 1989. Response of songbirds to glyphosate-induced habitat changes on clearcuts. Journal of Wildlife Management 53(1):64-71.

 

Thompson III, F. and  R. DeGraaf. 2001. Conservation approaches for woody, early successional communities in the eastern United States.  Wild. Soc. Bull.  29: 483-494.

 

Trani, M.K., R.T. Brooks, T.L. Schmidt, V.A. Rudis and C. M. Gabbard. 2001. Patterns and trends of early successional forests in the eastern United States. Wild. Soc. Bull. 29(2):413-424.

 

Warson, B.E., W.E. Palmer, P.T. Bromley and J.R. Anderson. 1998. Maintaining early-successional habitats using a metal wick herbicide applicator. Proc. Annu. Conf. Southeast. Assoc. Fish and Wildl. Agencies 52:265-273.

 

 

Wilson, M.D. and B.D. Watts. 2000. Breeding bird communities in pine plantations on the coastal plain of North Carolina. The Chat Vol. 64(1):1-14.

Woodward, A.A., A.D. Fink and F.R. Thompson III. 2001. Edge effects and ecological traps: effects on shrubland birds in Missouri. Journal of Wildlife Management 65(4):668-675.

Yahner, R.H. 2000. Long-term effects of even-aged management on bird communities in central Pennsylvania. Wild. Soc. Bull. 28(4):1102-1110.

Yahner, R.H. 2003. Responses of bird communities to early successional habitat in a managed landscape. Wilson Bull. 115(3):292-298.