Portnoy (1977) found three nesting colonies in 

 Louisiana; two were in marsh habitats and one was on 

 a site formed of dredged material. All birds observed 

 were nesting in woody shrubs. The species requires iso- 

 lated nesting areas far from human disturbance (Ander- 

 son 1978). 



In addition to pesticides and destruction of habi- 

 tat, exceptionally cold weather often causes spoon- 

 bill mortality. Nesting birds are highly sensitive, and if 

 disturbed they may abandon their nests for the season 

 (Anderson 1978). 



5.3.19 RED-TAILED HAWK {Buteo jamakensis) 



In the Chenier Plain, red-tailed hawks are winter 

 residents that arrive in early November and stay until 

 late March (Lowery 1974a). DaUy movement consists of 

 flights from roosting areas to hunting perches, and oc- 

 casional flights between hunting perches. Red-tails are 

 somewhat territorial in winter (Brown and Amadon 

 1968). The winter territory of six red-tails in Michigan 

 ranged from 1.6 to 5 km (1 to 3 mi) (Craighead and 

 Craighead 1956). 



Red-tailed hawks are found in a wide variety of 

 habitats, but usually reside where fields and forests are 

 intermingled. In the Chenier Plain these hawks occur 

 primarily in areas north of the coastal marshes or occa- 

 sionally on levees in the marsh. Red-shouldered hawks 

 {B. lineatus) are usually more common than red- 

 tailed hawks in swamp forests. 



The food of red-tailed hawks is primarily rodents, 

 rabbits and insects (Imliof 1976). Lowery (1974a) ex- 

 amined 65 stomachs of red-tailed hawks collected near 

 Baton Rouge and found cotton rats {Sigmodon 

 hispidus), rice rats (Oryzoniys palustris), harvest mice 

 {Reithrodontomys fulvescens) and house mice (Mus 

 musculus) exclusively. 



Red-tailed hawks are not yet known to nest in the 

 Chenier Plain but the species has extended its range from 

 northern Louisiana into central Louisiana. As with 

 other raptors, there may have been some recent repro- 

 ductive failures due to chlorinated hydrocarbons. Red- 

 tails are frequently shot even though they are protected 

 by the Migratory Bird Treaty Act. 



5.3.20 MARSH HAWK (Circus cyaneus) 



Marsh hawks are common residents in the Chenier 

 Plain, but do not nest there. Migrants usually arrive in 

 early September and some of these are present until 

 late May (Lowery 1974a). There are indications that 

 the species nests in Texas and Louisiana (Lowery 

 1974a, Oberholser 1974). The marsh hawk is more 

 active during twilight periods than most hawks and 

 can often be seen flying over marshes or prairies of 

 the Chenier Plain. While hunting, they often fly more 

 than 160 km (100 mi) in a day (Brown and Amadon 

 1968). The marsh hawk is more conspicuous than 

 most hawks when hunting because it flies low while 

 searching for prey. They may roost communally, but 



leave individually at dawn (Craighead and Craighead 

 1956). In winter, tliis species has a home range from 16 

 ha (40 a) to more than 1 mi^ (Brown and Amadon 

 1968). 



Marsh hawks feed over marshes, tidal flats, fields, 

 pastures, meadows, and prairies (Oberholser 1974). 

 They roost and nest on the ground and eat mammals, 

 snakes, frogs, insects, and other birds (Brown and Ama- 

 don 1968). 



5.3.21 KING RAIL (Rallus elegans) and CLAPPER 

 RAIL (R. longirostris) 



King rails and the clapper rails are common perma- 

 nent residents of the marshes of Louisiana and Texas. 

 King rail numbers increase in winter as northern mig- 

 grants arrive (Lowery 1974a). Because rails are secre- 

 tive and, therefore, difficult to observe, little is known 

 about daily movements. Telemetry studies of clapper 

 rails revealed that movements are restricted to small 

 areas with a radius of only 37 m (121 ft). Movement 

 occurs throughout the day and is more extensive in 

 winter (Sharpe 1976). 



These two large rails are similar in appearance, but 

 differ ecologically. The king rail is primarily a fresh- 

 water species whose distribution corresponds closely 

 with that of the muskrat. The king rail breeds in fresh 

 marshes and rice fields, whereas the clapper rail breeds 

 primarily in salt marshes. The two species may coexist 

 in brackish marshes (Meanley 1969, Lowery 1974a). 



King rails feed mainly on crustaceans, especially 

 crayfish, and aquatic insects, but will also eat fish, 

 crickets, and seeds of aquatic plants. King rails feed in 

 areas of dense plant cover or in narrow, open areas 

 where their cryptic coloration blends in with the marsh 

 background. They usually feed most heavily at dawn 

 and dusk (crepuscular), and at low tide (Meanley 1969). 



Clapper rails frequent areas of dense cordgrass or 

 needlerush. They are primarily crepuscular and feed at 

 low tide, mainly along tidal flats and muddy shores of 

 bayous and tidal creeks. Food consists mostly of crus- 

 taceans, especially crabs (up to 90% fiddler crabs), 

 snails, and other shellfishes (Sanderson 1977). Bateman 

 (1965) found that, in addition to fiddler crabs, square- 

 back crabs and periwinkle snails make up the bulk of 

 the diet. The fall diet is primarily small crabs and 

 snails. 



In Louisiana, the king rail nests over a 7- to 

 8-month period, beginning in March. The species pro- 

 duces several broods and each clutch contains 10 to 12 

 eggs. Sanderson (1977) reported a hatching success of 

 75%, but 50% of the young died during the first week 

 of life. King rails nest on the ground or slightly above 

 the ground, usually in buttonbush (Imhof 1976). 



Clapper rail nesting begins in February or early 

 March, peaks in mid-April to mid-July, and continues 

 into September. Density is about two to three nests per 

 hectare, primarily in taller cordgrass (greater than 55 

 cm or 21 in) (Oberholser 1974, Sharpe 1976). Nests 



236 



