Mercedes S Foster

Despite considerable research on lek-breeding birds, many aspects of the evolution of the lek soc... more Despite considerable research on lek-breeding birds, many aspects of the evolution of the lek social system, including the origin of male aggregation, remain unresolved. Originally, clusters may have formed passively as a byproduct of independent but concurrent responses by males to some external stimulus (e.g., a concentration of display sites, prominent food source, or a travel corridor commonly used by females) that drew them at a particular time to a site where they might increase their probabilities of encountering females. In contrast, male aggregation may have been active, with a male purposely seeking to associate with another male (or males) because proximity to that male allowed him to enhance his own reproductive success by improving his ability to attract females (i.e., learning from his associate) or to intercept females attracted to that male. To identify factors important in the formation of male aggregations, I studied these alternatives in the Dwarf Tyrant-Manakin (Tyranneutes stolzmanni), a species in which some breeding males occupy solitary courts where they attempt to attract females for reproduction, whereas other males occupy courts clustered into leks, where they interact to attract females. I compared habitat characteristics and resource availability at courts of grouped and solitary males as well as certain traits of the males in an attempt to distinguish between passive or active lek formation in this species. Little evidence suggests that Dwarf Tyrant-Manakins are passively clustered as a result of common attraction to or use of a limited or unevenly distributed resource. Several observations suggest the contrary. Evidence for the active aggregation of males is more promising, suggesting that males may associate with other males on the basis of their vocal behavior. The issue is confounded, however, by the observation that male call behavior appears to change with a change in social status. A definitive answer for T. stolzmanni will require additional analyses of vocal behavior as well as of the characteristics of the vocalizations themselves. Finally, the behavior and social organization of this species may reflect characteristics of the ancestral manakin line that gave rise to both the Tyrant and Core clades of modern manakins.

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Breeding Habits of the Toad Bufo coccifer in Costa Rica, with a Description of the Tadpole

Southwestern Naturalist, Nov 20, 1981

Bird Specimens and Documentation: Critical Data for a Critical Resource

The Condor, May 1, 1990

ABSTRACT As governments impose increasingly stringent regulations on the collection of bird speci... more ABSTRACT As governments impose increasingly stringent regulations on the collection of bird specimens and as man alters ever greater areas of habitat with the loss of many of their contained species, museum specimens increase immeasurably in importance. Yet at present, museum collections do not contain an adequate representation of the world&#39;s avifauna and, unfortunately, are not likely to do so. Thus, it is imperative that data associated with specimens that are obtained be as complete as possible. To this end, we describe categories of information with wide application to many types of studies, outline character states, and recommend standard forms of data notation. We recognize that under certain circumstances, it may be appropriate to record more limited data. However, we encourage at least those engaged in general collecting to record as many of these standard data as possible.

Dispersal of mimetic seeds of three species of Ormosia (Leguminosae)

Journal of Tropical Ecology, Jul 1, 1998

ABSTRACT. Seeds with ‘imitation arils’ appear wholly or partially covered by pulp or aril but act... more ABSTRACT. Seeds with ‘imitation arils’ appear wholly or partially covered by pulp or aril but actually carry no fleshy material. The mimetic seed hypothesis to explain this phenomenon proposes a parasitic relationship in which birds are deceived into dispersing seeds that resemble bird-dispersed fruits, without receiving a nutrient reward. The hard-seed for grit hypothesis proposes a mutualistic relationship in which large, terrestrial birds swallow the exceptionally hard mimetic seeds as grit for grinding the softer seeds on which they feed. They defecate, dispersing the seeds, and abrade the seed surface, enhancing germination. Any fruit mimicry is incidental. Fruiting trees of Ormosia spp. (Leguminosae: Papilionoideae) were observed to ascertain mechanisms of seed dispersal and the role of seemingly mimetic characteristics of the seeds in that dispersal. Seed predation and seed germination were also examined. Ormosia isthamensis and O. macrocalyx (but not O. bopiensis) deceived arboreally-foraging frugivorous birds into taking their mimetic seeds, although rates of seed dispersal were low. These results are consistent with the mimetic seed hypothesis. On the other hand, the rates of disappearance of seeds from the ground under the Ormosia trees, hardness of the seeds, and enhancement of germination with the abrasion of the seed coat are all consistent with the hard-seed for grit hypothesis. RESUMEN. Semillas con arilos falsos aparecen estar cubiertas en parte o completamente por pulpa o arilo, pero en realidad no llevan ninguna materia carnosa. El hipótesis semilla mímica propone que las semillas parecen frutos carnosos cuyas semillas están dispersadas por aves y que engañan las aves a dispersar sus semillas sin recibir una recompensa nutritiva — una relación parasítica. El hipótesis semilla dura para arenisca propone que aves grandes y terrestres tragan las semillas mímicas y excepcionalmente duras como arenisca para moler las semillas más suaves en que se alimentan; las aves defecan y dispersan las semillas, y las rascan, lo cual mejora la germinación — una relación mutua. Cualquier mimetismo es incidente. Se observaron árboles de Ormosia espp. (Leguminosae: Papilionoideae) con frutos para averiguar los mecanismos de dispersión de semillas y el papel que hacen las características aparentemente mímicas de sus semillas en esa dispersión. Se examinaron también la depredación y germinación de semillas. Las semillas mímicas de Ormosia isthamensis y O. macrocalyx (pero no O. bopiensis), engañaron aves frugivoras y arbóreas en comerlas, aunque las tasas de dispersión eran bajas. Estos resultados son consistente con el hipótesis semilla mímica. En cambio, las tasas de desaparición de semillas caídas de Ormosia, dureza de las semillas, y mejoramiento de germinación con la raedura de las capas de las semillas son consistente con el hipótesis semilla dura para arenisca.

Rain, Feeding Behavior, and Clutch Size in Tropical Birds

The Auk, Oct 1, 1974

THAT avian clutch size generally decreases with latitude has been

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Odd Couples in Manakins: A Study of Social Organization and Cooperative Breeding in Chiroxiphia linearis

The American Naturalist, Sep 1, 1977

Male long-tailed manakins (Chiroxiphia linearis) perform highly specialized communal or cooperati... more Male long-tailed manakins (Chiroxiphia linearis) perform highly specialized communal or cooperative displays to advertise their presence and to excite females for copulation. For the purpose of performing these displays, males form persistent associations (pairs or trios) analogous to those between members of heterosexual monogamous pairs. Associations persist through an entire breeding season or from year to year. One male is dominant in the association and responsible for all copulations. Evidence argues against a close kin relationship between males, and the behavior of the subordinate individual does not appear to be altruistic. The subordinate male probably receives a delayed benefit if he outlives his dominant partner. It is suggested that on re-pairing, he will assume the dominant position in the new partnership because of the psychological advantage gained as a result of his familiarity with and prior possession of the court where the displays are performed. Ultimately, his mating success will be greater than that of a solitary male who cannot perform alone, and, therefore, is incapable of attracting and exciting females. Long-tailed manakin social organization, male-male bonding, and communal courtship behavior can best be explained on the basis of selection operating on the individual.

Biodiversity of fungiinventory and monitoring methods

ABSTRACT Incluye bibliografía e índice Papers from a workshop held from October 15-19, at the Sys... more

Fruit pulp rewards for dispersers: Content, packaging, and relation to seed size

101st ESA Annual Meeting (August 7 -- 12, 2016), Aug 10, 2016

Rhinophrynus dorsalis Dumeril and Bibron (alma de vaca: Mexican burrowing toad)

The role of white-eyed vireos in the dispersal of Bursera Simaruba fruit

... 622 RUSSELL GREENBERG ET AL. ... 1990, as follows: February 1989 - five trees at Sian Ka&#x27... more ... 622 RUSSELL GREENBERG ET AL. ... 1990, as follows: February 1989 - five trees at Sian Ka'an; October 1989 - six trees at Sian Ka'an, three at Puerto Morelos and three at Chichén Itzá; March 1990 - 15 trees at Sian Ka'an ... All trees were at least 8 m tall and had 200-4000 fruits. ...