52 Rio Agua Dulce April 7 Groups of chiapensis calling - The surprising thing is that nigricaudatus was occurring in what I judged to be exactly the same type of situation in which chiapensis was occurring. This will require further work but I am sure that there is little if any difference in habitat preference in the area in question. I noted no wrens of either species in the dry fields back from the river. (see photos). Saw another th nigricaudatus nest placed 10 feet up in a loblom acacia in a clearing in a dense, rich stand of various bushes beneath and near large anote tree - a perfect situation for chiapensis I should think. One bird was seen to gather nesting fibers in the trees - not on the ground. Later, I saw a group of wrens foraging in small trees beneath large ones - these small-leaved lushy trees are very similar in growth form to trees frequent by humilis at Piedra la Cuesta, Guerrero - may be the same tree. I noticed that the small wrens made much use of the large trees - flying often to them and foraging thru the branches. They almost invariably sing in a rather exposed position from a high branch or limb in a tree - often a tall anote. Saw one small wren climb a foot or so up a vertical tree trunk - wood heater style - then fly to ground for a moment and work its way up thru the branches of a tree.