Manakin Species Research Articles

UNIDIRECTIONAL INTROGRESSION OF A SEXUALLY SELECTED TRAIT ACROSS AN AVIAN HYBRID ZONE: A ROLE FOR FEMALE CHOICE?

Hybridization can be an evolutionary creative force by forming new polyploid species, creating novel genetic variation or acting as conduits of potentially advantageous traits between hybridizing forms. Evidence for the latter is often difficult to find because alleles under positive selection can spread rapidly across a hybrid zone and sweep to fixation. In Western Panama, an avian hybrid zone between two species of manakins in the genus Manacus exists where the unidirectional introgression of bright, yellow plumage into a white population provides evidence for the importance of hybrid zones as conduits of advantageous traits. Several lines of indirect evidence suggest that sexual selection favoring yellow plumage drives this asymmetrical spread, but more direct evidence is lacking. Along the edge of the hybrid zone, both yellow- and white-collared manakins are found in the same mating arenas or leks and compete for the same females (“mixed leks”), providing us with a unique opportunity to understand the dynamics of yellow plumage introgression. We studied these mixed leks to determine whether yellow males have a mating advantage over white males and, if so, whether the mating advantage is driven by male-male interactions, female choice, or both. We found that yellow males mated more than white males, suggesting that sexual selection favoring yellow males can, indeed, explain the spread of yellow plumage. However, we found that this advantage occurred only in mixed leks where the frequency of yellow males is greater than white males. This suggests that the advantage of yellow males may depend on the presence of other yellow males, which may slow the rate of introgression in leks where yellow frequency is low such as in areas where yellow males are beginning to colonize the white population. This, along with the geographic barrier posed by major rivers in the hybrid zone, may initially limit or slow the spread of yellow plumage. Finally, we found that yellow and white males were similar in aggression and body size, and held comparable positions within leks. Because these traits or factors are often important in or dictated by aggressive male-male interactions, these comparisons indicate that male-male interaction is not the primary mechanism for the spread of yellow plumage. However, white and yellow males received similar numbers of courtship visits from females but differed in the number of matings, suggesting that females actively rejected white in favor of yellow males. Our results indicate that sexual selection by female choice has driven the unidirectional introgression of yellow plumage into the white population, providing a mechanism for how hybrid zones act as conduits of novel and advantageous traits.

CLIMATE CHANGE EFFECTS ON NEOTROPICAL MANAKIN DIVERSITY BASED ON ECOLOGICAL NICHE MODELING

Abstract ABSTRACT Assessing the nature and magnitude of potentialeffects of climate change on populations isimportant to anticipating effects on speciesdiversity for conservation planning. We usedecological niche modeling to predict present andfuture distributions of 49 species of manakins(Pipridae) and allies. Predictions forpresent-day distributions were highly coincidentwith independent test data, suggesting goodpredictive ability. Assuming no dispersal,projections of potential distributions underfour scenarios of climate change predicted that20% of manakin species would likely goextinct from their current ranges, and thatdistributions would in general be reduced andfragmented, regardless of the area ofpresent-day potential distribution or rarity.Predicted changes in potential distributions,spatial configuration of suitable habitats, andgeographic position of species ranges were moredramatic for species inhabiting flatlands thanfor montane species. These results are anexample of how ecological niche mo...

Vertical lek placement of forest-dwelling manakin species (Aves, Pipridae) is associated with vertical gradients of ambient light

We studied the interaction of ambient light and plumage colour in four sympatric neotropical manakin species which differ in signal colours and vertical lek placement. We estimated bird conspicuousness by modelling chromatic and achromatic background contrast of signal colours in tetrachromatic colour space. Spectral composition of ambient light varies gradually from the understory to the canopy and may affect where manakins lek. Under the given spatial requirements for their horizontal display flights, manakins place their leks at that position along the vertical gradient where ambient light increases chromatic and/or achromatic contrast of their colour signals against the background and/or within their coloration patterns. This suggests that physical factors can be important for placement of display sites, since they may critically influence the effectiveness and efficiency of conspecific communication.

Manakins (Pipridae) in Second-Growth and Old-Growth Forests: Patterns of Habitat Use, Movement, and Survival

AbstractWe used capture and recapture data (1985 to 1994) to examine seasonal variation in habitat use, movements within and among habitats, and survival rates of manakins (Manacus candei, Corapipo altera, Pipra mentalis, P. pipra) in northeastern Costa Rica. Manakins were captured in young and old second-growth woodlands in the lowlands and in old-growth forest at approximately 50, 500, and 1,000 m. Manakin species differed in their use of habitats, with old-growth forest species showing large and predictable seasonal variation in capture rates. Corapipo capture rates in lowland (nonbreeding) habitats were greater during the wet season than during the dry season and were greater in old-growth forest than in second growth. Capture rates at 500 m were higher in the dry season. Pipra mentalis capture rates were high in second growth and old growth. Capture rates were higher in the wet season and were correlated with capture rates of Corapipo, indicating that at least some individual P. mentalis migrate along the elevational gradient. P. pipra capture rates were highest at 1,000 m; few individuals descended to lowlands in the wet season. Manacus capture rates were highest in young second growth and did not vary between wet and dry seasons. Use of second-growth habitats by species typically associated with old-growth forests illustrates the value of maintaining a mosaic of habitats to accommodate seasonal changes in use of habitats. Contrary to expectations based on lek mating systems, there was little evidence that movements within habitats (i.e. recapture distances) varied between sexes. Yet, recapture percentages were higher in all species for adult females than males. Adult survival rates were ∼0.75 for Manacus in young second growth, 0.62 for Corapipo in old-growth forest at 50 m and 0.66 at 500 m, and 0.70 for Pipra mentalis in lowland old-growth forest. Results support the suggestion that geographic variation in survival rates may be common in the tropics and illustrate the need for examining survival rates separately by age and sex.

MANAKINS (PIPRIDAE) IN SECOND-GROWTH AND OLD-GROWTH FORESTS: PATTERNS OF HABITAT USE, MOVEMENT, AND SURVIVAL

We used capture and recapture data (1985 to 1994) to examine seasonal variation in habitat use, movements within and among habitats, and survival rates of manakins (Manacus candei, Corapipo altera, Pipra mentalis, P. pipra) in northeastern Costa Rica. Manakins were captured in young and old second-growth woodlands in the lowlands and in old-growth forest at approximately 50, 500, and 1,000 m. Manakin species differed in their use of habitats, with old-growth forest species showing large and predictable seasonal variation in capture rates. Corapipo capture rates in lowland (nonbreeding) habitats were greater during the wet season than during the dry season and were greater in old-growth forest than in second growth. Capture rates at 500 m were higher in the dry season. Pipra mentalis capture rates were high in second growth and old growth. Capture rates were higher in the wet season and were correlated with capture rates of Corapipo, indicating that at least some individual P. mentalis migrate along the elevational gradient. P. pipra capture rates were highest at 1,000 m; few individuals descended to lowlands in the wet season. Manacus capture rates were highest in young second growth and did not vary between wet and dry seasons. Use of second-growth habitats by species typically associated with old-growth forests illustrates the value of maintaining a mosaic of habitats to accommodate seasonal changes in use of habitats. Contrary to expectations based on lek mating systems, there was little evidence that movements within habitats (i.e. recapture distances) varied between sexes. Yet, recapture percentages were higher in all species for adult females than males. Adult survival rates were ∼0.75 for Manacus in young second growth, 0.62 for Corapipo in old-growth forest at 50 m and 0.66 at 500 m, and 0.70 for Pipra mentalis in lowland old-growth forest. Results support the suggestion that geographic variation in survival rates may be common in the tropics and illustrate the need for examining survival rates separately by age and sex.

Interspecific synchrony and asynchrony in the fruiting phenologies of congeneric bird-dispersed plants in Panama

Plants potentially compete for seed dispersal. Selection may favour temporally segregated fruiting phenologies to minimize this competition and also to maintain resident populations of dispersal agents. Alternatively, selection may favour temporally aggregated fruiting phenologies when the effectiveness of seed dispersal agents varies seasonally or when large, synchronous fruit displays enhance dispersal. These evolutionary scenarios assume that plants share seed dispersal agents. This assumption and temporal overlap in fruiting phenologies were evaluated for the Miconia and Psychotria of central Panama. These two genera accounted for 18 and 27%, respectively, of 1096 fleshy fruits found in regurgitation or faecal samples taken from 2054 birds of 103 species netted in the forest understorey. Two species of manakins accounted for 62% (123/200) of all Miconia fruit taken. Three species of manakins and three species of migratory thrushes accounted for 97% (282/292) of all Psychotria fruits taken. There is a high potential for intrageneric competition for seed dispersal for both plant genera. Null model analyses showed that the fruiting phenologies of Miconia (14 species) are segregated in time, while fruiting of Psychotria (21 species) is highly aggregated. The Miconia were found in up to 24% of the diet samples for the two manakin species, suggesting that Miconia may be a critical resource for both species. The Psychotria fruited when the diversity of understorey fruits was greatest, suggesting a high potential for both intra- and extrageneric competition. The abundance and nomadism of the six bird species that consumed most Psychotria fruit peaked when the Psychotria fruited, supporting the enhancement hypothesis.

Ultraviolet cues affect the foraging behaviour of blue tits

The function of avian ultraviolet (UV) vision is only just beginning to be understood. One plausible hypothesis is that UV vision enhances the foraging ability of birds. To test this, we carried out behavioural experiments using wild–caught blue tits foraging for cabbage moth and winter moth caterpillars on natural and artificial backgrounds. The light environment in our experiments was manipulated using either UV–blocking or UV–transmitting filters. We found that the blue tits tended to find the first prey item (out of four) more quickly when UV cues were present. This suggests that UV vision offers benefits to birds when searching for cryptic prey, despite the prey and backgrounds reflecting relatively little UV. Although there was no direct effect of UV on the time taken to find all four prey items in a trial, search performance in the absence of UV wavelengths tended to increase over the course of an experiment. This may reflect changes in the search tactics of the birds. To our knowledge, these are the first data to suggest that birds use UV cues to detect cryptic insect prey, and have implications for our understanding of protective coloration.

Sexual selection and the evolution of mechanical sound production in manakins (Aves: Pipridae)

I surveyed and described modulated, non-vocal, mechanical sounds of the lek-breeding Neotropical manakins (Pipridae). Variation among manakin species in mechanical sound production, repertoire size, acoustic structure, associated feather specialization, and mechanical sound production mechanisms were analysed comparatively in the context of a phylogenetic hypothesis for the family. Mechanical sound production has probably evolved five or six times independently and been lost once within the 42 species of manakins. Complex mechanical sound repertoires have also evolved independently several times. Acoustic structure of these sounds indicates that at least four different physical mechanisms of mechanical sound production have evolved: short, broad-frequency spectrum pulses; short, low-frequency pulses; aerodynamic vortices; and harmonic oscillations. All well-known mechanical sounds in manakins are associated with obvious wing movements and sexually dimorphic wing feather specializations. Both primary and secondary wing feather specializations have evolved convergently within the family for the production of short, broad-frequency mechanical sound pulses. Two less well-known manakin clades also have tail feather specializations that may function in mechanical sound production. A concentrated-changes test documented that the dynamic patterns of evolution in mechanical sound production in the polygynous manakins are highly unlikely by chance alone. Intersexual selection for acrobatic display may have created subsequent opportunities for the evolution of novel preferences for incidental non-vocal sounds produced by acrobatic movements. Novel female preferences for these mechanical sounds led to further elaboration of these sounds and to the evolution of complex mechanical sound repertoires in independent lineages of the family.

Display Behavior and Natural History of the Yellow-Crowned Manakin (Heterocercus flavivertex: Pipridae)

The behavior and natural history of the Yellow-crowned Manakin (Heterocercus flavivertex, Pipridae) were observed on the Rio Ventuari in northern Territorio Federal Amazonas, Venezuela. Male flavivertex have a solitary lek breeding system, a display repertoire including five distinct vocalizations, several display elements, and a probable mechanical display sound. The tail-shiver display, in which the cocked tail is prominently featured, has not been observed in other Heterocercus species, but this display element may be an explanation for the evolution of the unique tail shape in the genus. Other flavivertex display elements, such as the above-the-canopy display flight, are behavioral homologs shared with other Heterocercus species. Female H. flavivertex construct hanging cup nests that are similar in architecture, composition, and placement to other manakin species. The diet of H. flavivertex is apparently composed of a greater quantity of insects than other manakin species. The evolution of display, morphology, diet, and social behavior in Heterocercus is discussed.

Plumage Pigment Differences in Manakins of the Pipra Erythrocephala Superspecies

-We investigated the carotenoids found in the head feathers of three members of the Pipra erythrocephala superspecies by chromatographic, spectrophotometric, and chemical means. The Golden-headed Manakin (P. erythrocephala) primarily deposited yellow hydroxycarotenoids in its head feathers, predominately lutein. Red keto-carotenoids were also deposited locally. Canthaxanthin, for instance, was identified in the tips of nape feathers. In contrast, the Red-headed Manakin (P. rubrocapilla) deposited mostly orange and red ketocarotenoids. An orange pigment identified as a-doradexanthin was the most abundant. The common red pigments astaxanthin and canthaxanthin were also present. Finally, feathers of the red-headed Round-tailed Manakin (P. chloromeros) yielded a complement of carotenoids very similar to the Red-headed Manakin's. In addition, the Round-tailed Manakin deposited moderate amounts of rhodoxanthin, a plant keto-carotenoid of pronounced red hue. Within individual Red-headed Manakins, we observed differences in total carotenoid content and composition among head regions that differed slightly in color. The distal and proximal portions of individual feathers also differed markedly. We discuss possible physiological and biochemical mechanisms for these conditions, and suggest their relationship to the mechanisms responsible for the species-specific differences in manakin coloration. We reveal the probable origin of the Latin misnomer for the Golden-headed Manakin. Received 2 August 1988, accepted 2 August 1988. THE four species of Neotropical manakins that compose the Pipra erythrocephala superspecies (Snow 1979) differ conspicuously in the combination of their head, thigh, and underwing colors (Table 1). The difference in head color is particularly striking between the Golden-headed Manakin (Pipra erythrocephala) and its close relatives. The golden top and sides of the head of P. erythrocephala, belying its scientific name, contrast sharply with the bright red head of the other three allospecies. The colors involved are generally bright, and presumably implicate carotenoid pigments (Brush 1981). However, the biochemical and genetic basis of the color differences remains unexplored. P. erythrocephala is closely related to the Redheaded Manakin (P. rubrocapilla), with which it has been grouped in a single species (P. e. erythrocephala and P. e. rubrocapilla of Hellmayr 1929). The distribution of P. erythrocephala and P. rubrocapilla at their area of closest contact is delimited largely by the Amazon River. The 3To whom all reprint requests should be sent. occurrence of morphological differentiation associated with rivers is often found among understory Amazonian forest birds, a pattern largely unique to Amazonia (e.g. Hellmayr 1910, Snethlage 1913). One interpretation is that rivers act as barriers to gene flow and serve as geographical isolating mechanisms (Sick 1967). Capparella (1987, in press) reported large genetic distances between the two manakins, in excess of the mean for avian species [Nei's (1978) D = 0.101; avian mean 0.0440 ? 0.0221 SD, Barrowclough 1980] based on allozyme studies. Moreover, fixed differences were detected at three loci, a condition often lacking between undisputed avian species. Carotenoid pigments, responsible for most of the bright colors in birds, are relatively wellknown chemically. Furthermore, considerable work has been concerned with their biochemical modification and processing in birds (reviewed in Brush 1981). Differences in feather carotenoids are determined by both the processes responsible for their absorption and transport, and the metabolic capacities of the 34 The Auk 106: 34-41. January 1989 This content downloaded from 157.55.39.135 on Sun, 03 Jul 2016 06:06:41 UTC All use subject to http://about.jstor.org/terms January 1989] Pigment Differences in Pipra 35 birds to modify the pigments. Hence, carotenoid analysis can be used to infer physiological, and the underlying genetic, differences. In addition to providing specific plumage color and patterns (Fox and Hopkins 1966, Fox et al. 1967, Brush 1970, Brush and Johnson 1976, Troy and Brush 1983), carotenoid differences account for color polymorphisms (Volker 1964, Brush and Seifried 1968, Johnson and Brush 1972), subspecific plumage variation (Test 1942, Ford and Simpson 1987), and plumage variants (Volker 1964, Brush 1970, Hudon and Brush in press). To elucidate the nature of the physiological differences that confer species specificity of coloration in the manakins, we determined the pigment constitutions responsible for the difference in head color between P. erythrocephala and P. rubrocapilla. The Round-tailed Manakin (P. chloromeros), another member of the P. erythrocephala superspecies, was also ex-

Sugar-Tasting Ability and Fruit Selection in Tropical Fruit-Eating Birds

Abstract The sugar-tasting abilities of four species of tanagers and two species of manakins were tested. Three tanager species were able to detect differences in diets containing 8%, 10%, and 12% sugar. In pairwise choice trials, they preferred the diet highest in sugar. Neither species of manakin discriminated among the three diets. This apparent difference in tasting abilities of tanagers and manakins may be a result of their fruit-handling techniques. Tanagers crush fruits in their bills, thereby releasing juices onto their tongues. Manakins swallow fruits whole; their tongues rarely encounter fruit juice. Hence, manakins' fruit-handling technique is poorly suited for sensing the taste cues in fruit juices. Variation in fruit sugar concentration is common within and among plant species and is great enough to be detected by birds. Birds probably have selected for sweeter fruits.

Fruit Choice in Neotropical Birds: The Effect of Distance Between Fruits on Preference Patterns

The influence of distance between fruiting plants on choice patterns of four species of tanagers and two species of manakins was experimentally tested in a lowland rain forest in Costa Rica. Paired clusters of two fruit species (Miconia affinis and Urera caracasana) were presented on each of two perches separated by selected distances ranging from 0.3 to 6.4. When the two perches were closest together, all the birds ate the preferred berries, M. affinis, on both perches before eating the less preferred U. caracasana. At the extreme perch separation distance, all but one of the birds ate both species of fruits on the first perch before flying to the second perch. The distance at which each bird switched between the two feeding sequences was correlated with the strength of their preference for one species of fruit over another. Manakins switched at greater separation distances than did tanagers. Since manakins take most of their fruit on the wing, the difference in switch distance is likely related to their flight pattern, but no consistent correlation with simple morphological characteristics (wing—loading or aspect ratio) was found. The results suggest that, in the field, less preferred items may often be taken when more preferred fruits are spaced even moderately far apart. The sequence of feeding and, by implication, diet breadth appears to be a consequence of the abundance and spacing of available foods; hence, degree of generalization is a dynamic feature of a bird's foraging pattern. This result supports the prediction that travelling time is an important determinant of prey and patch choice.

Die Balz der Schmuckvögel(Pipridae)

A comperative survey is given on the courtship of 25 species of manakins. The facts stated are mostly based on observations made by the author in Brazil since 1939. After a condensed description of the courtships of the different kinds of manakins, the subject is summarized by the following points of view: 1. Analysis of the different elements of manakin's display, the distribution of these elements through the different species and the occurence of some similar elements of behaviour in the Tyrants and Cotingas; 2. Age and sex of the birds participating in the communal displays, general character of courtship of the manakins, and interspecific relations between manakins; 3. Phylogenetic and systematic conclusions.