Publications

The Banded Ground-cuckoo (Neomorphus radiolosus) is a rare, endangered, and poorly known species endemic to the Choco´ Biogeographic Zone. We summarize 7 months of data from radio tracking an adult in northwestern Ecuador. Home range estimates were 42.2 ha (minimum convex polygon) and 49.9 ha (95% kernel analysis); the core area was 3.4 ha (50% kernel analysis). The bird favored undisturbed habitat and avoided secondary forest. It was primarily insectivorous and rarely associated with army ants (Eciton sp.) and not with mammals. Breeding occurred from March through June and the marked bird was seen with an unmarked individual throughout the study. The Banded Groundcuckoo has a large home range, limited dispersal ability, and apparently depends on undisturbed forest. Deforestation and habitat fragmentation appear to be the gravest threats facing the species. Received 15 December 2006. Accepted 28 April 2007.

Over the last 30 years, sexual selection has become one of the most influential and rapidly growing areas within evolutionary biology and behavioral ecology. Sexual selection has important effects on the evolution of life history traits, mating systems and morphology, and also has been suggested as a factor that promotes speciation. Avian systems have played an essential role as models in the development of sexual selection theory. However, most studies have focused on temperate species, although they account for less than one quarter of avian species worldwide. Therefore, before applying existing theories universally, caution is advised, especially considering latitudinal trends in life history traits and evolutionary strategies. Here, we brought together five tropical bird studies covering different aspects of sexual selection theory. Two studies detail the evolutionary processes involved with plumage signals; one of these deals with the influence of female sensory drive on the evolution of male plumage, and the second investigates how non-random female mate choice can promote genetic introgression along a hybrid zone. A third study examines how sex differences in diet can lead to temporal asynchrony between periods of peak male display activity and female nesting. A fourth study details how differences in lek spatial structure and social organization influence the degree of male reproductive skew among manakins. The fifth study examines differences in the intensity of sexual selection in temperate and tropical taxa and assesses current knowledge regarding the frequency of extra-pair paternity among regions. The contributions of these studies to our current understanding of sexual selection are discussed. Accepted 14 October 2007. Key words: Extra-pair paternity, hybridization, lekking, mate choice, reproductive skew, sexual selection, tropical birds, tropical-temperate comparisons, visual signals.

The Mache-Chindul mountains in north-west Ecuador have a very rich but poorly known avifauna. Here, we report on range extensions for eight species of birds not previously recorded in this area, namely Ornate Hawk-Eagle Spizaetus ornatus, Rufescent Screech Owl Otus (ingens) colombianus, Oilbird Steatornis caripensis, Spotted Barbtail Premnoplex brunnescens, Ochre-breasted Antpitta Grallaricula flavirostris, Pale-eyed Thrush Platycichla leucops, Pale-vented Thrush Turdus obsoletus and Black-lored Yellowthroat Geothlypis auricularis. Birds were captured in mist-nets, or observed on multiple occasions, at Bilsa Biological Station, in Mache-Chindul Ecological Reserve, prov. Esmeraldas. The majority of species were previously known in Ecuador only from the slopes of the Andes, thus these records represent westward range extensions and new minimum elevational limits.

The Banded Ground-cuckoo (Neomorphus radiolosus) is a rare and endangered bird species whose basic biology is poorly known. We provide the first information on nesting biology for the species. We documented two nesting attempts in the Mache-Chindul Ecological Reserve, Esmeraldas Province, northwest Ecuador. Both the first nest, active in March and April 2005, and the second nest, active in May 2005, were in primary rain forest. Both nests were 5 m above ground in small understory trees (Melastomataceae). A pair of adult Banded Ground-cuckoos attended the first nest and contributed equally to incubation, brooding, and provisioning of a single nestling. The nestling spent 20 days in the nest from hatching to fledging and was fed a wide range of both invertebrates (primarily grasshoppers) and vertebrates (mainly small frogs). The chick fledged successfully. The second nest, also attended by a pair of adults, failed during incubation. We relate our findings to what is known of other ground-cuckoo species and discuss the conservation implications of our results. Received 23 February 2006. Accepted 3 September 2006.

Although macaws are arguably the most widely recognized species of bird from Neotropical rainforests, little is known of their basic biology or demography in the wild. In Ecuador, as in other Neotropical countries, it is suspected that several species of macaw are declining in response to human activity and habitat alteration but there is little hard data supporting this supposition. In this paper, we present one full year of data on macaw populations from a relatively pristine site in the Ecuadorian Amazon, and compare this site to two other sites with intermediate and relatively high levels of human activity. At Tiputini Biodiversity Station, a pristine terra-firme forest, macaws were more common in the dry season than in the wet season. This pattern is the opposite of that recently reported for seasonally inundated forests in Peru, suggesting that macaws may make large-scale, seasonal movements across habitat types. We employed the same sampling methodology for shorter periods of time at Sacha Lodge, characterized by intermediate levels of human activity, and at Jatun Sacha Biological Station, characterized by relatively high levels of human activity and habitat degradation. We recorded an intermediate number of macaws at Sacha Lodge, and the lowest densities at Jatun Sacha. Three groups of indicator taxa sampled at all three sites showed a similar pattern. These data provide a baseline for future demographic studies of macaws in the Ecuadorian Amazon and lend tentative support to the idea that macaw population declines may be linked to human activity and habitat alteration

Long-wattled Umbrellabirds Cephalopterus penduliger are restricted to the Choco´ Biogeographical Region, an area with exceptional levels of avian diversity and endemism. Due to widespread habitat loss and hunting pressure, the species is considered globally Vulnerable and Endangered within Ecuador. Little is known of the species’ basic biology. This paper presents data on the first confirmed nest recorded for the species. The nest was found in June 2002 atop a tree fern Cyathea sp. located in secondary forest near Mindo, north-west Ecuador, at 1,600 m in the subtropical zone of the Andean slope. Data collected during incubation and nestling provisioning suggest that females may be responsible for all parental care. At the nest, the female provided food an average of once per hour, and brought roughly twice as many invertebrate food items as vertebrate or regurgitated food items. A male was never seen at the nest. In addition to presenting data from the nest, we compare Long-wattled Umbrellabirds to congeners and discuss implications for the conservation of this species.

In most species of fairy-wren (Malurus spp.), males are known to carry brightly coloured petals and display them to conspecifics.A lthough petal-carrying by males is often considered an inter-sexual courtship display, anecdotal observations suggest that it may also serve an intra-sexual aggressive function. In this study, we tested hypotheses for the function of petal-carrying displays in the Red-backed Fairy-wren (Malurus melanocephalus) through behavioural observations and aviary-based experiments. All petal displays observed were perpetrated by males, with 90% directed toward females and 10% toward other males. Most petal displays were performed by males in nuptial plumage during intrusions into neighbouring territories, and most displays coincided with the potential fertile period of the female to whom the display was directed. Display items consisted primarily of seeds from Gahniasp. and flowers from Banksiasp. and Lantanasp., all of which were red or pink and similar to the red backs of nuptial males. Aviary trials found no significant difference in the responses by adult females or adult males tostimulus males with or without petals, substantiating neither a courtship role nor an aggressive role for the display. On the basis of the context of displays in the field, we conclude that the petal-carrying display in the Red-backed Fairy-wren primarily serves an inter-sexual,courtship function, though we could not rule out an intra- sexual, aggressive function.

The red-backed fairy-wren is a socially monogamous passerine bird which exhibits two distinct types of breeding male, bright males that breed in bright red and black plumage and dull males that breed in dull brown plumage. Most males spend their first potential breeding season in dull plumage and subsequent breeding seasons in bright plumage, but a relatively small proportion of males develop bright plumage in their first breeding season. This study quantifies morphology, behavior, and reproductive success of dull and bright males to assess the adaptive costs and benefits of bright plumage while controlling for age. Older bright males (two years of age or older) attempted to increase their reproductive success via copulations with extrapair females, whereas younger (one-year old) bright males and dull males did not. Thus, older bright males spent less time on their own territories, intruded on neighboring groups with fertile females more frequently, gave more courtship displays, and had larger sperm storage organs than did younger bright males and dull males. Microsatellite analyses of paternity indicate that the red-backed fairy-wren has extremely high levels of sexual promiscuity, and that older bright males had higher within-brood paternity than dull males or younger bright males. Regardless of age, bright males were more attractive to females in controlled mate choice trials than were dull males, and both age classes of bright males obtained higher quality mates earlier in the breeding season than did dull males, when nesting success was higher. In conclusion, although it appears that bright plumage increases access to higher quality mates, age also plays a central role in determining a male’s overall reproductive success because of the high levels of sexual promiscuity exhibited by the red-backed fairy-wren. Key words. Delayed plumage maturation, Malurus melanocephalus, red-backed fairy-wren, sexual promiscuity, sexual selection.

Europa Island is a major breeding place for green turtles (Chelonia mydas; 0.7 to 2.4 million juvenile turtles hatch there annually), Great Frigatebirds (Fregata minor; 700 to 1100 breeding pairs), and Lesser Frigatebirds (Fregata ariel; 1000 to 1200 pairs). By visual observation, we quantified the proportions of males, females, and juveniles of both frigatebird species prospecting over the hatching sites and preying on hatchling turtles. Of 1828 juveniles observed hatching at daytime (35 separate turtle emergences), 1632 were immediately eaten by male Great Frigatebirds. Only 10 hatchlings were preyed upon by female Great Frigatebirds; the remaining 186 were captured by juvenile Great Frigatebirds. Such feeding behavior was not observed in Lesser Frigatebirds. We suggest that the sexual and species differences in hatchling turtle predation are due to size differences between the two species and between male and female Great Frigatebirds. Key words: feeding ecology, frigatebirds, green turtle, predation, sexual size dimorphism.

In many bird and mammal species, males are signi¢cantly larger than females. The prevailing explanation for larger-sized males is that sexual selection drives increased male size. In addition, researchers commonly assume that the extent of dimorphism indicates the strength of selection for increased size in males. Here, through reconstruction of ancestral morphology for males and females of one large avian clade we present data that contradict this assumption and illustrate that selection for decreased female size explains `male-biased’ dimorphism ca. 50% of the time. Our ¢ndings are also inconsistent with ecological niche partitioning between the sexes and increased breeding bene¢ts from reduced female size as general explanations for the evolution of size dimorphism within the clade. We conclude that it is incorrect to assume sexual dimorphism results from a single selective factor, such as directional sexual selection on increased male size. Rather, we suggest that the selective forces leading to sexual dimorphism may vary between species and should be tested on a case-by-case basis using a phylogenetic approach. Keywords: Aves; niche-partitioning hypothesis; sexual dimorphism; sexual selection