Myioborus Miniatus Research Articles

Unexplained recurrent features of the plumage of birds

Unexplained recurrent features of the plumage of birds

Chapter 8: Phylogeography and Adaptive Plumage Evolution in Central American Subspecies of the Slate-Throated Redstart (Myioborus Miniatus)

Abstract The Slate-throated Redstart (Myioborus miniatus) is a common warbler of montane forests from northern Mexico to Argentina. We examined phylogenetic structure and plumage pattern in relation to subspecific taxonomy across the broad geographic range of this species. Phylogenetic analysis of two complete mitochondrial protein-coding genes (subunits 2 and 3 of NADH dehydrogenase) from 36 individuals, representing 10 of the 12 subspecies, revealed four clades, three of which showed general concordance with subspecific classification. However, in a Central American clade, four subspecies (hellmayri, connectens, comptus, and aurantiacus) could not be resolved by the molecular phylogenetic analysis, even though populations of hellmayri and connectens are currently geographically isolated from those of comptus and aurantiacus by the Nicaraguan lowlands. The genetic homogeneity within this clade suggests a late Pleistocene range expansion at a time when today's montane forest types existed at lower elevati...

Breeding Biology and Nesting Success of the Slate-Throated Whitestart (Myioborus miniatus) in Monteverde, Costa Rica

Abstract I examined the breeding biology and nesting success of the Slate-throated Whitestart (Myioborus miniatus), a socially monogamous neotropical warbler, for five breeding seasons (2000–2004) in Monteverde, Costa Rica, near the center of its broad geographic range. Nesting was strongly seasonal, extending from late March through the end of June and coinciding with the end of the dry season and the onset of the rainy season in mid-May. Females constructed domed nests on open steep slopes or in banks along roads and trails. Mean clutch size was 2.9 eggs, and the mean incubation period was 14.2 days. Females performed all incubation of eggs and brooding of young nestlings, but both males and females fed nestlings and fledglings. Mean provisioning rate at nests when young were 5–9 days of age was 20.3 feedings/hr, and females fed young at a significantly higher rate than males (11.7 vs. 8.3 feedings/hr, respectively). Nestlings reached mean adult body mass of 9.5 g ∼ day 7–8, and mean age at fledging was...

Breeding Biology and Natural History of the Slate-Throated Whitestart in Venezuela

Abstract We provide details on the breeding biology of the Slate-throated Whitestart (Myioborus miniatus) from 126 nests found during seven breeding seasons, 2002–2008, at Yacambu National Park, Venezuela. Nesting activity peaked in late April and May. Only the female built the nest and incubated the eggs. Males rarely visited the nest during these stages. Mean clutch size (2.1 ± 0.04 eggs, n = 93) was the smallest recorded for the Slate-throated Whitestart. Incubation and nestling period lengths were 15.3 ± 0.31 (n = 21) and 10.8 ± 0.24 (n = 7) days, respectively. Attentiveness (% of time on the nest) during incubation (59 ± 1.6%, n = 52) was similar to other tropical warblers and much lower than northern relatives. This caused a relatively low egg temperature (34.40 ± 0.33° C, n = 6 nests, 20 days) compared with north temperate birds. Both parents fed nestlings and increased their provisioning rates with nestling age. Growth rate based on nestling mass (k = 0.521 ± 0.015) was faster than for...

Modeling the flocking propensity of passerine birds in two Neotropical habitats

We examined the importance of mixed-species flock abundance, individual bird home range size, foraging height, and foraging patch characteristics in predicting the propensity for five Neotropical passerine bird species (Slaty Antwren, Myrmotherula schisticolor; Golden-crowned Warbler, Basileuterus culicivorus; Slate-throated Redstart, Myioborus miniatus; Wilson's Warbler, Wilsonia pusilla; and Black-and-white Warbler, Mniotilta varia) to forage within flocks, rather than solitarily. We used study plots in primary mid-elevation forest and in shade coffee fields in western Panama. We expected that all species would spend as much time as possible flocking, but that the social and environmental factors listed above would limit compatibility between flock movements and individual bird movements, explaining variability in flocking propensity both within and among species. Flocking propensity was well predicted by home range size and flock abundance together, for four of the five species. While flock abundance was uniform across plots, home range sizes varied among species and plots, so that home range size appeared to be the principle factor limiting flocking propensity. Estimates of flock abundance were still required, however, for calculating flocking propensity values. Foraging height and patch characteristics slightly improved predictive ability for the remaining species, M. miniatus. In general, individual birds tended to join flocks whenever one was available inside their home range, regardless of a flock's specific location within the home range. Flocking propensities of individual species were lower in shade coffee fields than in forests, and probably vary across landscapes with variations in habitat. This variability affects the stability and species composition of flocks, and may affect survival rates of individual species.

EVOLUTIONARY SIGNIFICANCE OF GEOGRAPHIC VARIATION IN A PLUMAGE‐BASED FORAGING ADAPTATION: AN EXPERIMENTAL TEST IN THE SLATE‐THROATED REDSTART (MYIOBORUS MINIATUS)

Geographic variation in the plumage pattern of birds is widespread but poorly understood, and in very few cases has its evolutionary significance been investigated experimentally. Neotropical warblers of the genus Myioborus use their contrasting black-and-white plumage to flush insect prey during animated foraging displays. Although previous experimental work has demonstrated that white plumage patches are critical to flush-pursuit foraging success, the amount of white in the plumage shows considerable interspecific and intraspecific geographic variation. We investigated the evolutionary significance of this geographic variation by experimentally decreasing or increasing the amount of white in the tail of slate-throated redstarts (Myioborus miniatus comptus) from Monteverde, Costa Rica, to mimic the natural extremes of tail pattern variation in this species. In addition to measuring the effects of plumage manipulation on foraging performance, we performed field experiments measuring the escape response of a common insect prey species (an asilid fly) using model redstarts representing four different Myioborus plumage patterns. Our experiments were designed to test four hypotheses that could explain geographic variation in plumage pattern. Compared to controls, experimental birds with reduced-white tails that mimic the plumage pattern of M. miniatus hellmayri of Guatemala showed significant reductions in flush-pursuit foraging performance. In contrast, the addition of white to the tail to mimic the plumage pattern of M. miniatus verticalis of Bolivia had no significant effect on foraging performance of Costa Rican redstarts. In field experiments with asilid flies, model redstarts simulating the plumage of M. miniatus comptus of Costa Rica and M. miniatus verticalis of Bolivia elicited greater responses than did models of other Myioborus taxa with either less or more white in the plumage. The results of our experiments with both birds and insects allow us to reject two hypotheses for geographic variation in plumage pattern: (1) that geographic variation is a nonadaptive result of genetic drift, and (2) that selection for enhanced flush-pursuit foraging performance generally favors increased white in the plumage, but evolutionary trade-offs constrain the evolution of extensive patches of white in some geographic regions. Instead, our results suggest that geographic variation in the plumage pattern of Myioborus redstarts reflects adaptation to regional habitat characteristics that enhances flush-pursuit foraging performance.

EVOLUTIONARY SIGNIFICANCE OF GEOGRAPHIC VARIATION IN A PLUMAGE-BASED FORAGING ADAPTATION: AN EXPERIMENTAL TEST IN THE SLATE-THROATED REDSTART (MYIOBORUS MINIATUS)

Geographic variation in the plumage pattern of birds is widespread but poorly understood, and in very few cases has its evolutionary significance been investigated experimentally. Neotropical warblers of the genus Myioborus use their contrasting black-and-white plumage to flush insect prey during animated foraging displays. Although previous experimental work has demonstrated that white plumage patches are critical to flush-pursuit foraging success, the amount of white in the plumage shows considerable interspecific and intraspecific geographic variation. We investigated the evolutionary significance of this geographic variation by experimentally decreasing or increasing the amount of white in the tail of slate-throated redstarts (Myioborus miniatus comptus) from Monteverde, Costa Rica, to mimic the natural extremes of tail pattern variation in this species. In addition to measuring the effects of plumage manipulation on foraging performance, we performed field experiments measuring the escape response of a common insect prey species (an asilid fly) using model redstarts representing four different Myioborus plumage patterns. Our experiments were designed to test four hypotheses that could explain geographic variation in plumage pattern. Compared to controls, experimental birds with reduced-white tails that mimic the plumage pattern of M. miniatus hellmayri of Guatemala showed significant reductions in flush-pursuit foraging performance. In contrast, the addition of white to the tail to mimic the plumage pattern of M. miniatus verticalis of Bolivia had no significant effect on foraging performance of Costa Rican redstarts. In field experiments with asilid flies, model redstarts simulating the plumage of M. miniatus comptus of Costa Rica and M. miniatus verticalis of Bolivia elicited greater responses than did models of other Myioborus taxa with either less or more white in the plumage. The results of our experiments with both birds and insects allow us to reject two hypotheses for geographic variation in plumage pattern: (1) that geographic variation is a nonadaptive result of genetic drift, and (2) that selection for enhanced flush-pursuit foraging performance generally favors increased white in the plumage, but evolutionary trade-offs constrain the evolution of extensive patches of white in some geographic regions. Instead, our results suggest that geographic variation in the plumage pattern of Myioborus redstarts reflects adaptation to regional habitat characteristics that enhances flush-pursuit foraging performance.

SLATE-THROATED REDSTARTS (MYIOBORUS MINIATUS) BREEDING IN MADERAS DEL CARMEN, COAHUILA, MEXICO

The breeding range of the slate-throated redstart (Myioborus miniatus) stretches from South America to Mexico, where it extends northward along the Sierra Madre Oriental to southeastern Coahuila and along the Sierra Madre Occidental to southern Chihuahua and Sonora. We report the discovery of slate-throated redstarts breeding in the Maderas del Carmen mountains in Coahuila. This represents a range extension of approximately 400 km and is, to our knowledge, the northernmost breeding record for this species.

Mixed-Species Flocking and Foraging Behavior of Four Neotropical Warblers in Panamanian Shade Coffee Fields and Forests

Abstract We quantified foraging rates and foraging visibility metrics for four Neotropical warblers—Slate-throated Redstart (Myoborus miniatus), Golden-crowned Warbler (Basileuterus culicivorus), Wilson's Warbler (Wilsonia pusilla), and Black-and-White Warbler (Mniotilta varia)—under flocking and solitary conditions in western Panama to test hypotheses regarding the relative influences of predation pressure and social facilitation on foraging behavior. We also compared foraging behavior in primary forests and in traditionally managed shade coffee fields for two species (Slate-throated Redstart and Wilson's Warbler) to estimate spatial variation in foraging behavior and compare it to variation due to social situation (flocking or solitary). We then assessed the contribution of spatial variation in flocking propensity to the total spatial variation in foraging rates within species. We observed very little overall within-species variability in foraging behavior between social situations or study locations. Only Slate-throated Redstart's behavior was consistent with the hypothesis that flock membership reduces predation pressure and therefore reduces the amount of foraging time spent being vigilant against predators, allowing birds to forage more quickly and find more prey items per minute. No species' behavior supported the hypothesis that flocking birds forage more efficiently than solitary birds by obtaining useful information from flock mates about the location or suitability of foraging resources or techniques. The effort required to find prey items did not vary between study locations (forest and coffee field plots) for Wilson's Warbler. Because flocking also had no effect on foraging behavior of Wilson's Warbler, a reduction in flocking propensity in coffee habitat, relative to forest, did not cause further foraging behavior differences between study locations. Spatial variation in Slate-throated Redstart's foraging behavior independent of a flocking effect was minor; but flocking affected foraging rates, and flocking propensity was lower in coffee fields than in forest, so that location and flocking effects combined to widen foraging rate differences between locations. Thus, variations in flocking behavior and foraging behavior interacted differently for those two species.

MIXED-SPECIES FLOCKING AND FORAGING BEHAVIOR OF FOUR NEOTROPICAL WARBLERS IN PANAMANIAN SHADE COFFEE FIELDS AND FORESTS

Abstract We quantified foraging rates and foraging visibility metrics for four Neotropical warblers—Slate-throated Redstart (Myoborus miniatus), Golden-crowned Warbler (Basileuterus culicivorus), Wilson's Warbler (Wilsonia pusilla), and Black-and-White Warbler (Mniotilta varia)—under flocking and solitary conditions in western Panama to test hypotheses regarding the relative influences of predation pressure and social facilitation on foraging behavior. We also compared foraging behavior in primary forests and in traditionally managed shade coffee fields for two species (Slate-throated Redstart and Wilson's Warbler) to estimate spatial variation in foraging behavior and compare it to variation due to social situation (flocking or solitary). We then assessed the contribution of spatial variation in flocking propensity to the total spatial variation in foraging rates within species. We observed very little overall within-species variability in foraging behavior between social situations or study locations. O...

Scare Tactics in a Neotropical Warbler: White Tail Feathers Enhance Flush–Pursuit Foraging Performance in the Slate-Throated Redstart (Myioborus Miniatus)

AbstractFlush–pursuit foragers use exaggerated and animated foraging movements to flush potential prey that are then pursued and captured in flight. The Myioborus redstarts comprise 12 species of flush–pursuit warblers found in montane forests of the American tropics and subtropics. All members of the genus have contrasting black-and-white tail feathers that are exposed by spreading the tail during animated foraging displays. Plumage pattern and tail-spreading behavior were examined to see how they affected flush–pursuit foraging performance of the Slate-throated Redstart (Myioborus miniatus) in Monteverde, Costa Rica. Although flycatching was the most common foraging tactic used by Slate-throated Redstarts, flush–pursuit foraging increased in both frequency and intensity when birds were feeding nestlings. Flush–pursuit prey attacks occurred more frequently following hops in the spread-tail foraging posture than hops in more typical warbler-like posture, suggesting that tail-spreading behavior assists in startling and flushing potential prey. The hypothesis that the white tail feathers enhance flush–pursuit foraging was tested by means of a plumage-dyeing experiment. After locating nests containing young 5–7 days old, I captured the male and female at the nest and assigned one member of each pair to the experimental treatment group; its mate served as a control. For experimental birds, a permanent marker was used to blacken the white tips of the three outer retrices. For sham-darkened controls, the naturally black tips of the three inner retrices were also “blackened”. Experimental birds with darkened tail feathers were significantly less successful in flush–pursuit foraging, showed a significantly lower overall rate of prey attack, and fed their nestlings at a significantly lower rate than did their sham-darkened mates. For experimental birds, only 7.6% of hops in the spread-tail posture were followed by an attack on a prey item, compared to 20.9% of hops for controls. These experimental results, similar to those obtained recently by Jabłoński (1999) for the congeneric Painted Redstart (Myioborus pictus), indicate that white tail feathers are critically important in startling potential prey and raise questions about interspecific and intraspecific geographic variation in plumage pattern in the genus.

SCARE TACTICS IN A NEOTROPICAL WARBLER: WHITE TAIL FEATHERS ENHANCE FLUSH–PURSUIT FORAGING PERFORMANCE IN THE SLATE-THROATED REDSTART (MYIOBORUS MINIATUS)

Abstract Flush–pursuit foragers use exaggerated and animated foraging movements to flush potential prey that are then pursued and captured in flight. The Myioborus redstarts comprise 12 species of flush–pursuit warblers found in montane forests of the American tropics and subtropics. All members of the genus have contrasting black-and-white tail feathers that are exposed by spreading the tail during animated foraging displays. Plumage pattern and tail-spreading behavior were examined to see how they affected flush–pursuit foraging performance of the Slate-throated Redstart (Myioborus miniatus) in Monteverde, Costa Rica. Although flycatching was the most common foraging tactic used by Slate-throated Redstarts, flush–pursuit foraging increased in both frequency and intensity when birds were feeding nestlings. Flush–pursuit prey attacks occurred more frequently following hops in the spread-tail foraging posture than hops in more typical warbler-like posture, suggesting that tail-spreading behavior assists in...

Nasal Mites from Birds of a Guatemalan Cloud Forest (Acarina: Rhinonyssidae)

A survey of the nasal mites from Guatemalan cloud forest birds is reported. Seventy-eight birds, representing 10 families and 18 species, were examined. Prevalance of infection was 24%. Two new species are described: Sternostoma darlingi from Mitrephanes phaeocercus (Tyrannidae) and S. pencei from Empidonax flavescens (Tyrannidae). New host records are reported for S. pirangae from Chlorospingus ophthalmicus (Thraupidae), S. hutsoni from Catharus dryas (Turdidae), Ptilonyssus sairae from Chlorospingus opthalmicus (Thraupidae) and Myioborus miniatus (Parulidae), P. euroturdi from Catharus dryas (Turdidae), P. tyrannus from Empidonax flavescens and Mitrephanes phaeocercus (both Tyrannidae), and Tinaminyssus ixoreus from Catharus dryas (Turdidae). The subspecies Ptilonyssus euroturdi mimicola Fain and Hyland is synonymized with the nominate subspecies. Data are presented to suggest that the Rhinonyssidae may be a polyphyletic assemblage.

First United States Record for the Slate-Throated Redstart, and First Specimens of various Species for New Mexico

First United States Record for the Slate-Throated Redstart, and First Specimens of various Species for New Mexico