PIF
Priority Bird for Southern Blue
Ridge
This dull colored wood-warbler is known for its amazing vocal abilities. Throughout its range it is noted for the habit of constantly wagging its tail up and down while moving along the ground, or while sitting singing on tree limbs. This pronounced habit is reflected in that both the genus and species name mean "tail-wagger." The loud, ringing song of the Louisiana Waterthrush compensate for its drab coloration. Song notes include clear, slurred whistles followed by a complex jumble of shorter phrases. This noticeably distinct song is easily loud enough to be heard over the background noise of the rushing water streamside habitats the waterthrush prefers. It forages primarily on the ground along flowing streams, but will also search for food in stagnant pools of water along swamp edges. Migration will also find it in parks and gardens at times. Easily heard, this bird often takes some searching to locate due to its cryptic colors that blend in well in dark streamside environments.
This bird most frequently breeds along the borders of woodland streams, especially fast-flowing ones with gravel bottoms. It is a neotropical migrant that winters in similar habitat in parts of Mexico, Central America, northwestern South America and the West Indies. Neotropical (New World) migratory birds breed during summer in temperate North America, migrating north each spring from wintering areas, then fly back south to spend the bulk of the year in Mexico, Central or South America, or the Caribbean.
This waterthrush is a species of the eastern United States where the habitat type it uses is most common. Its breeding range is apparently expanding northward into such states as New York, Connecticut, Vermont and Michigan, most likely in response to the reforestation of areas that were extensively lumbered in the late 1800’s and early part of the 20th century.
Breeding Bird Survey (BBS) data may not be an accurate method for determining population status of this species. Most BBS routes are run after the Louisiana Waterthrush has finished singing, and do not adequately census the riparian habitat it uses. BBS data show a long-term decline in breeding population size overall, but the trend since 1978 shows a very slight increase. However, in the east they seem to be slightly declining. This is a difficult bird to survey with general methods, since it sings early in the season and often at odd times of the day like mid-morning or just before sunset.
Male and female birds are identical in plumage. The Louisiana Waterthrush is very similar to the Northern Waterthrush, a bird that does not breed in our state but does migrate through, and often uses similar habitat. The Louisiana Waterthrush has a larger bill, a whiter and broader strip over its eye, less streaking in the throat area, and is generally whiter in color on its sides, belly and under the tail than the Northern Waterthrush. Both waterthrushes walk with a teetering motion similar to the Spotted sandpiper.
Adults have small, hard to see, white spots at the tips of their tail feathers. Juveniles and even second year birds usually lack these spots. The adult birds also have a hidden, whitish median crown strip which young birds lack.
The Louisiana Waterthrush breeds most frequently along gravel-bottomed streams flowing through deciduous forest. It may occasionally breed in cypress swamps and bottomland forests along mud-bottomed streams, but in rather low densities. It uses similar habitat during migration and on the wintering grounds, but may be found in parks, gardens and thickets as long as water is available.
The linear territories are established along streams by males beginning as early as mid March in North Carolina. Males begin singing as soon as they arrive in the spring, and countersinging and chases are common near territorial borders early in the breeding season. A primary purpose of song in this species is to attract a mate, as singing virtually ceases after pair formation. Nest construction begins about the time of spring leaf-out, with both sexes building the nest. The preferred nest sites are small hollows or cavities near the root base of upturned trees, within the bank of a streamside or under fallen logs. In areas of the state where streams flow through heavily populated areas, there are often excessive amounts of run-off due to extensive impervious surfaces (roads, parking lots, etc.). The result can be flooding during nesting time, with nests, or even eggs or young birds being lost. Suburban streams flood more frequently now than even 10 or 20 years ago, and this may be bad news for the waterthrush. Thus the advantage of protection from predators or even cowbirds by nesting under the overhang of streamside banks may be lost in some parts of the state.
Foraging behavior is closely tied to flowing water, with extensive probing into crannies in streamside rocks and roots. Prey is also taken from leaves, stems of plants, leaf litter, soil and moss. The main food items taken are aquatic insects and invertebrates, as well as small flying insects. In addition, mollusks, earthworms, crustaceans and even small fish and amphibians may be taken. The waterthrush has an interesting habit of also foraging on floating debris. This bird is an extremely fast feeder, with up to 10 or more feeding maneuvers per minute typical.
This is a bird of the eastern United States, with birds absent from most of Florida during the breeding season and just barely getting into southern Maine. In North Carolina, it is fairly common breeder in the mountains and Piedmont, but less so in the Coastal Plain. Some North Carolina mountain streams may have a singing bird every 100 yards or so early in the springtime. It winters from northern Mexico south through Central America to Panama, also occurring commonly in the Caribbean region and rarely in northern South America. Occasional birds winter within the southeastern United States.
The Louisiana Waterthrush, a nighttime migrant, sometimes collides with buildings or radio towers during migration. As with most neotropical migrants, good estimates of the number of birds impacted is rare. Detailed studies to document the impact these structures are having on migratory landbirds is badly needed. Extensive deforestation on the wintering grounds is likely a serious problem in certain areas. Birds that use suburban habitats are likely affected by increased flooding regimes in streams. Protection of forest tracts and water resources inhabited by this species during the breeding and wintering seasons is needed. The Louisiana Waterthrush is ranked as a species in need of monitoring attention in the southern United States by the US Fish & Wildlife Service, and as a species of concern by Partners in Flight in the south.
Peterson Field Guides: Warblers by Dunn and Garrett, 1997, Houghton Mifflin Company
The Bird Life of Texas by Oberholser, 1974, Univ. of Texas Press