By the early 1990's, communication among Mexican field workers suggested that a declining trend was the norm for all leatherback nesting populations on the Pacific coast. In the absence of ample coverage of the entire shoreline, however, investigators could not rule out the possibility that the geography of nesting had shifted and that, for reasons unknown (but perhaps related to intense El Niño episodes in the late 1980's and early 1990's), females were favoring a different suite of beaches than they had previously been the case.