L O U I S I A N A B R E E D I N G W O O D WARBLERSWARBLERS This public document was published at a total cost of $5,175.00. Two thousand copies of this public document were published in this first printing at a cost of $5,175.00. The total cost of all printings of this document, including reprints, is $5,175.00. This document was published by the Barataria-Terrebonne National Estuary Program, NSU Campus, P.O. Box 2663, Thibodaux, LA 70310, to provide the public with environmental information under the authority of LA R.S. 30:2011. This material was printed in accordance with standards for printing by state agencies established pursuant to R.S. 43:31. L O U I S I A N A B R E E D I N G W O O D WARBLERSWritten by Bill Fontenot Richard DeMay Illustrated and designed by Diane K. Baker Photography by Greg Lavaty The Estuary Program would like to thank the many members of the “Protection of Habitat for Migratory and Resident Bird” Action Plan Team for their tireless support and commitment to “making things happen”. It is that support and commitment that is the strength of the Estuary Program. I N T R O D U C T I O N imble, energetic, boldly patterned, and brightly colored, North America’s woodN warblers epitomize the lavish degree of biodiversity bestowed upon the New World. One can only imagine the wonder in the ocean-weary eyes of America’s first European explorers when they encountered this elegant display of living jewels, for no Palearctic animal group could approach such opulence in color and variety. Even in the New World, few animal groups can physical appearance. The overwhelming majority match not only the diversity in colors and patterns, of wood warblers possess small bodies, averaging but also the diversity in behavior and niche-occupa- about five inches in length and about one-third of an tion possessed by the wood warblers. Some behave as ounce in weight – some 20% smaller and 35% ligh- nuthatches do, scurrying flat against trunks and large ter than a House Sparrow. Their bills are generally branches of trees while combing bark crevices for thin and needle-like, specialized for capturing small invertebrate prey. Others act like flycatchers, adapted arthropods such as insects, caterpillars, insect eggs, to catching flying insects in mid air. Some appear mollusks, and spiders. Similarly, their thin, weak- distinctly wren-like, replete with bobbing heads and looking legs are designed for maneuvering between cocked tails. Some of the ground-hugging species tight, twiggy and leafy spaces. behave as thrushes do. But most have carved their In order to taxonomically separate them from own distinctive niches out of the wooded ecosystems Old World warblers (which are actually more closely of the Americas, chasing down food items in a defini- related to the thrushes) of Europe, Asia, India, tively furtive style all their own. Africa, and Australia, New World warblers are com- Regardless of geographical range or niche, all monly referred to as the “wood warblers.” At least wood warblers share 115 species of wood warblers occur in the Americas, common cha- from throughout all of Canada south through all of racteristics. the United States, Mexico, and Central America, As with and down through northern Argentina in South all animal America. Fifty-three of these species breed in the groups, United States. it is the Taxonomically, wood warblers are thought to foraging be closely related to the tanagers; and recent DNA behavior studies have indicated that they share many genetic of warblers affinities with the orioles. In fact, ornithologists -- the way in believe that all “nine-primaried songbirds,” including which they procure the tanagers, orioles and blackbirds, wood warblers, their food -- which grosbeaks, sparrows, and buntings are closely related. ultimately dictates their 2 Blackburnian Warbler 3 As recently as 1992 all of these groups were combi- the tanagers, grosbeaks, thrushes, and orioles, ned into one family – the Emberizidae – but more most warbler species are classified as Neotro- recently each of these groups have been reassigned pical migrants, moving all the way south from Considering that warblers are to individual families. Currently, all wood warblers their temperate breeding grounds down into the primarily insectivorous, most species reside within the family Parulidae. American tropics each fall, and returning north are forced to move out of their Here in North America, wood warblers achieve each spring. Several warbler species, however, have their peak species diversity between the southern adapted more varied diets, allowing them to linger breeding ranges each year as cool Great Lakes region and the Canadian maritime within the southern reaches of the temperate weather sets in, reducing insect provinces, southward through the Appalachian zone (i.e. extreme southern California and the U. Mountains. S. Gulf Coast) for the duration of each winter. activity. Most North American wood warbler species These species are referred to as Neararctic migrants are highly migratory. Considering that warblers are - sometimes called temperate migrants – along primarily insectivorous, most species are forced to with the more familiar species of ducks and geese move out of their breeding ranges each year as cool that spend winter months across the vast wetland weather sets in, reducing insect activity. Along with habitats of Louisiana. Pine Warbler 4 W A R B L E R S I N L O U I S I A N A t least 74 distinctive habitat types and accompanying plant communi- ties Ahave been identified and cataloged across Louisiana’s 33 million acres. Nearly half of these habitat types are wooded, most of which are utilized by wood war- blers on a seasonal or permanent basis. Louisiana’s geographical location near the center of the North American continent and on the north- central coast of the Gulf of Mexico – at the cusp of the temperate north and the tropical south – allows our state (along with Texas) to receive and conduct a much higher-than-average amount of migratory bird traffic compared to other states. Well over half of the 810 bird species living in the U.S. and Canada – nearly 460 species – have been recorded in Loui- siana. To date, 46 of the 53 warbler species native to the United States and Canada -- a whopping 87% -- have been recorded in Louisiana. Louisiana is a warbler-friendly state. On a temporal scale, general warbler presence in Louisiana is dictated by season, and can be subdi- vided into five categories: 1) Year Round Residents, bases of pine needle clus- 2) Neotropical Migrant Breeders, 3) Spring and Fall ters for insects and other Transients, 4) Winter Residents, and 5) Accidental arthropods which find refuge and Casual Species Occurrences. there even during the colder win- ter months. It will also readily seek out Year-Round Residents wild berries and selected seeds (i.e. pine and As a strongly migratory group, few wood warbler sweetgum) during the winter months, thus allowing species fall into this category. Moreover, the majority it a comfortable year round food supply throughout of U.S. warbler species breed to the north of Louisi- the Gulf Coastal and Middle/Southern Atlantic ana. Combine these two factors, and the list of po- Coastal states, including all of Louisiana. tential Louisiana year-round residents is dramatically Wren-like in behavior, the Common Yellow- pared. Indeed, the only two species which routinely throat forages in dense, low vegetation, most often occur on a year round basis are the Pine Warbler and associated with damp or wet habitats which tend to the Common Yellowthroat. mitigate the severity of winter temperatures, allow- The Pine Warbler is among the most deliberate ing arthropods to remain at least somewhat active. hunters of the wood warblers, methodically prob- The Common Yellowthroat enjoys the largest ing its relatively large bill into protected places such North American breeding range of any warbler, as pinecones, sweetgum balls, bark crevices, and the absent only from the southwestern deserts and 5 Snow Goose Chen caerulescens American White Pelican Pelecanus erythrorhynchos extreme northern Canada. This species breeds During spring migration, hormonally-induced throughout Louisiana, but becomes a bit more scarce breeding urges propel most Neotropical migrants in the northern half of the state during the winter northward directly over the Gulf of Mexico. In the months. According to ornithologists Dunn and United States, the geographical focal point of this Garrett (in Warblers, 1997), the bulk of north- great northbound river of birds includes the Louisiana ern breeding Common Yellowthroats overwinter In the United States, the geographical within the coastal marshes of the southern Atlantic, focal point of this great northbound southern Pacific, and Gulf of Mexico coastal plains of the United States, explaining the profusion of this river of birds includes the Louisiana species within this habitat throughout Louisiana’s and upper Texas coasts, where inclem- coastal zone each winter. ent weather often grounds the birds Neotropical Migrant Breeders at first available landfall, creating Neotropical Migrant Breeders describes those wood warbler species that nest in Louisiana, but spectacular birdwatching events migrate out of the state each fall and winter. Twelve known as “fallouts.” species fall into this category: Northern Parula, Yellow-throated Warbler, Prairie Warbler, Black & White Warbler, American Redstart, Prothonotary and upper Texas coasts, where inclement weather Warbler, Worm-eating Warbler, Swainson’s Warbler, often grounds the birds at first available landfall, Louisiana Waterthrush, Kentucky Warbler, Hooded creating spectacular birdwatching events known as Warbler, and Yellow-breasted Chat. Each of these “fallouts.” During such events it is not unusual for a species is discussed in detail in the next section of good birder to record 15 or more warbler species in a this publication.