192 BULLETIN 2 03, UNITED STATES NATIONAL MUSEUM 



take root again in the mud, thus forming an almost impenetrable 

 tangle of roots and branches in an ever-widening band extending out- 

 ward from the dry land. Its dense, dark foliage forms a low, gloomy 

 forest of branches in which this well-named warbler finds a secure 

 retreat and to which it is almost exclusively confined. It has not 

 always been easy to obtain in these tangles, for Brewster (1902) says 

 that— 



during January, February, and a part of March, 1887, Mr. Frazer repeatedly 

 visited all the mangrove thickets that he could find near La Paz, and made every 

 effort to secure a good series of these Warblers, but he took only eight in all 

 and did not shoot more than a pair in any one day. He notes the bird as "rare," 

 but adds that "its numbers increased slightly in March." It cannot be very 

 numerous here at any time, for the total area covered by its favorite mangroves is 

 very limited. Indeed, the place where most of his specimens were obtained 

 "comprises only about two acres, through which winds a small creek, fordable at 

 low tide; but at high water everything is submerged up to the lower branches 

 of the mangroves. I always found the birds working near the surface of the 

 water on the stems of the mangroves or hopping about on the mud, but the 

 males resorted to the tops of the bushes to sing. Their notes are similar in 

 general character to those of the Yellow Warbler." 



W. W. Brown was evidently more successful a little later in the 

 season, for, in that same locality in May and June, he collected a large 

 series of these beautiful birds for several American collections, mainly 

 Col. John E. Thayer's. He wrote to Colonel Thayer (1909) : 



I found the Mangrove Warbler a rare bird, but my previous experience with 

 this species in Panama, the Pearl Islands, and in Yucatan is what made me 

 successful. I learned its song and alarm note in 1893. The first morning I went 

 into the mangrove swamps of La Paz I whistled the song of the Yucatan species 

 and the birds answered me; this is the secret of my success, for the species is 

 very secretive in its habits. I found it so difficult to get that I offered fifty 

 cents apiece to the duck hunters and others, including the local taxidermist, 

 but they all failed to get it! By covering eight miles of territory I generally 

 managed to get four or five. Sometimes when I shot one it would fall in the 

 mangroves, with a tide running fast. Under such conditions it generally took 

 ti long time to find it, and a great deal of cutting with the machete. 



Referring to the form found in El Salvador, Dickey and van Rossem 

 (1938) remark: "To add to the difficulties in tlie path of the collec- 

 tor, the brown and yellow plumage of the males blends perfectly with 

 ihe dead or dying mangrove leaves which are kept in continual motion 

 by the sea breeze." 



Nesting. — Brown sent Colonel Thayer (1909) three nests of the 

 mangrove warbler, only one of which contained a set of three eggs. 

 Of this he says : "The nest with eggs is made (and the others resemble 

 it very much) of light green fern down, cobwebs, and light-colored 

 dried grasses, with a few white feathers plastered on the outside. 

 It is beautifully lined with feathers. It is not so perfectly shaped 

 or so well made as the Yellow Warbler's nest." 



