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Mixed Diglossini, May 2, 1965, II.

[[margin]] Cy [[/margin]]  really is quite remarkable!  I must see if they are equally gregarious in the other parts of the Western Cordillera (and in the Central Cordillera).  Does the gregariousness of the Ap here suggest that they are almost exclusively insectivorous (like Sittis)?  Probably not.  The GT's which occur in mixed flocks here usually seem to be eating fruit.  So do other tanagers.  In any case, it is obvious that whatever the advantages of joining mixed flocks may be, the advantages of joining a large flock presumably are larger than those of joining a small flock.

[[margin]] Cy [[/margin]]  What the gregariousness of the local Cys [[underlined]] does [[/underlined]] suggest is that they are [[underlined]] not nectarivorous! [[/underlined]]

[[margin]] Cy [[/margin]]  If the Cys here are obligate commensals, this might explain why the individual seen this morning sang so frequently while with the mixed flock.  Having no "territory of its own", it may have to sing while with mixed flocks in order to "warn off" other individuals of the same species who might not be aware that it was in the area.

[[margin]] Sitti WCC Cy Albi [[/margin]]  Some aspects of the territorial arrangements of the local Diglossines are becoming clear.  The commensal Sittis, WCC's, and Cys probably range over the territories of the local resident, territorial, Albis without coming into [[underlined]] significant [[/underlined]] social contact with them.  (This seems to be characteristic of the relations between commensals and territorial residents everywhere.)  "Glauc"s (if they are a distinct species) may be as resident, local, and territorial as Albis.  And certainly the ranges of the two "species" overlap at lower altitudes here.  There is no evidence, however, that the territories of individuals of the two species overlap.  But both species are so rare (apparently) that it would be rash to assume that the territorial separation is due to special behavior mechanisms (rather than "chance" alone).
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