From 1936 to 1998 I kept notes on the Riverside Wren (Thryothorus semibadius) in southern Pacific Costa Rica. Early in this interval, the wrens lived chiefly along the shores of wider streams flowing through the forests and around marshy openings in the lowlands. With widespread deforestation, they tended to forage and nest farther from the watercourses. Their short, ringing songs sound above the clamor of mountain torrents. They ear small invertebrates. At all seasons they sleep alone or two or three together. in well-enclosed nests such as they occupy for breeding. Only the female incubates the two eggs, Laking long sessions and long recesses. The incubation period is 18 or 19 d. Both parents attend the young. The nestling period is 16 d. The parents lead newly emerged fledglings to sleep in a nest with their mother. For a year and a half, I followed the activities of a family of four that lived in our garden.

Harmonization, the primary constructive process of the Universe, builds its materials into patterns of increasing amplitude, complexity, and coherence. On the grand scale it condenses clouds of cosmic dust into solar systems, so stable that they endure for ages. On the smallest scale it unites the primary particles, electrons, protons and neutrons, in atoms, with which it composes molecules, crystals, and, finally, living organisms. The growth of a plant, binding inorganic substances from earth and air in a creation that is both complex and beautiful, is an excellent example of harmonization. Dependent upon plants for their nourishment, animals carry harmonization a step farther, into the psychic realm, where morality, social order, art, science, and philosophy are among harmonization most advanced achievements.

A rich ecosystem Iike a tropical rain forest contains three categories of organisms: ( 1) the sustainer green photosynthetic plants of a1l growth forms, theír poIlinators, seed dispersers, and próteétors'from injurious insects, and mostIy obscure decomposers Cif dead malter that replenish the soil's fertility; (2) the associates or "guests", a diverse group that appears to be rleither necessary foc the maintenance of the ecosystem nor injurious to it; and (3) the "enemies", predators great andsmall, parasites externa! and interna!, pathogens, etc. that torture, mutilate, oc destroy membersof the fmt two categories, which coexist harmoníously, rarely injuring on¡; another. Iurge conservationists. to give preferentia! treatment to these comp¡¡tible categories, ceasing to apply inadequate resources to theprotection oc increase of members of the third category, if nor trying to eliminate sorne of them. By promoting biocompatibility, or compatible biodiversity, instead of biodiversity of undefined limits, we might rnake a more harmonious, productive, and enjoyable natural world.

and only those sites in shade and with low maximum temperatures ultimately are used to incubate eggs. Acknowledgments.-We thank Barry Brady, refuge manager, Presquile National Wildlife Refuge, for permission to study warblers there. Hill Carter kindly gave us access to the study area from historic Shirley Plantation. Harold Robinson, U.S. National Museum of Natural History, helped L.B.B. identify bryophytes. Susan Moyle Studlar and Larry Clark kindly shared their knowledge of mosses and bird nests with us. We also thank Larry Clark, Richard N. Conner, and Douglass H. Morse for reviewing drafts of this manuscript. Members of several Virginia Commonwealth University ornithology classes helped with maintenance of nest boxes.

IbisVolume 131, Issue 2 p. 303-304 Courtship of the Rufous Piha Lipaugus unirufus Alexander F. Skutch, Alexander F. Skutch Quizarrd, 8000 San Isidro de El General, Costa Rica.Search for more papers by this author Alexander F. Skutch, Alexander F. Skutch Quizarrd, 8000 San Isidro de El General, Costa Rica.Search for more papers by this author First published: April 1989 https://doi.org/10.1111/j.1474-919X.1989.tb02776.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume131, Issue2April 1989Pages 303-304 RelatedInformation

Journal Article Connie Hagar: The life history of a Texas birdwatcher Get access Connie Hagar: The life history of a Texas birdwatcher. -Karen Harden McCracken. Texas A&M. University Press, College Station. xvi + 296 p. $18.95. Alexander F. Skutch Alexander F. Skutch Quizarra, 8000 San Isidro de El General, Costa Rica Search for other works by this author on: Oxford Academic Google Scholar The Condor, Volume 89, Issue 2, 1 May 1987, Pages 446–447, https://doi.org/10.2307/1368507 Published: 01 May 1987

A survey of the clutch size of 2 1 7 species of passerines of the humid neotropics shows that two is the prevailing number of eggs, sets of one and three are less frequent, and larger sets are rare. Contrary to what we should expect from the theory of maximum reproductionthat birds rear as many young as they can adequately nourishunaided females commonly have broods as large as those attended by both parents, sometimes with helpers. Failure to find consistent correlation between clutch size and number of nest attendants, diet, habitat, or type of nest (other than the well-known tendency of hole-nesters to rear larger broods) leads us to seek some factor, or factors, that profoundly influence the reproduction of most birds of the humid neotropics. Not to be neglected is the high percentage of nest failures, greater in forest than in neighboring clearings and plantations, and greater at low than at high elevations. Available evidence leaves the effect of human visits on nest losses uncertain; hatching failure due to infertility, faulty incubation, or other intrinsic factors appears to be no greater in the tropics than at higher latitudes; predation is certainly responsible for most losses. The major factor responsible for the small clutches of tropical birds of many kinds appears to be, as Cody and Ricklefs have argued, the less strongly contrasting seasons of the humid tropicsa measure of which is the annual march of evapotranspirationas compared with northern lands. The restrained reproductive effort of tropical birds is adjusted to their low annual mortality in a climate that does not force birds to confront a season of scarcity and stress unless they undertake hazardous migrations. Moreover, the high incidence of predation on nests makes it advantageous to limit the energy expended on a brood, so that, if this fails, strength remains for repeated trials. Also, the smaller the brood, the fewer the feeding visits that may reveal the nest's location to predators. Because ornithology was born in the north temperate zone where broods tend to be large, we ask why the broods of tropical birds are so small. If more ornithologists had grown up in the tropics, we would be asking why birds at high latitudes lay so many eggsa question easier to answer. RESUMEN. Un estudio del tamano de las nidadas de 217 especies de passeriformes de las regiones humedas neotropicales, muestra que el numero prevaleciente de huevos en una nidada es dos; siendo menos frecuentes nidadas de uno o tres huevos y son raras las nidadas mas grandes. Contrariamente a lo que deberiamos esperar, si consideramos la teoria de maxima reproductionque las aves crian tantos polluelos como les es posible alimentarlas hembras que no tienen ayuda cuidan nidadas tan grandes como aquellas nidadas que son atendidas por ambos padres, que algunas veces tienen ayudantes. El no encontrar una correlaci6n consistente para la relaci6n entre el tamano de la nidada y el numero de encargados del nido, dieta, habitat o tipo de nido (otra que la tendencia conocida para los anidadores en huecos que crian grandes nidadas), nos hace considerar ciertos factores que influyen profundamente la reproduction de la mayoria de las aves de las regiones humedas de los neotripicos. Algo que no debe ser descuidado es el alto procentaje de fracasos de anidaci6n, los cuales son mayores en el bosque que en las zonas abiertas o plantaciones cercanas y mayor a baja que a altas elevaciones. No esta claro que efecto tienen las visitas humanas en las peYdidas de nidos; fracasos de eclosion debido a infertilidad, incubaci6n defectuosa, u otros factores intrinsecos que parecen no ser mas importantes en los tr6picos que en otras latitudes mas elevadas; la depredaci6n es por cierto la mayor responsable en la mayoria de las perdidas. El factor mayormente responsable por el tamano pequeno de las nidadas de las aves neotropicales de cualquier tipo parece ser, tal como lo discutiesen Cody y Ricklefs, el menor contraste entre las estaciones en los tr6picos humedoslo cual puede ser medido por la marcha anual de evapo-transpiracionsi se compara con tierras septentrionales. El esfuerzo reproductivo moderado de las aves tropicales, se ajusta a la baja mortalidad anual en un clima que no fuerza a las aves a enfrentar una estacidn de escasez y stress, a no ser que participen en migraciones riesgosas. Mas aun la gran incidencia de depredacidn en los nidos hace ventajoso limitar el gasto de energia en una nidada, de

The SciencesVolume 23, Issue 6 p. 18-21 Miniatures and Giants Alexander F. Skutch, Alexander F. Skutch Alexander F. Skutch, a botanist and naturalist, has spent the past forty-seven years living on a remote farm in Costa Rica. This essay is adapted from his forthcoming Nature Through Tropical Windows. Copyright ©1983 by the regents of the University of California. To be published by the University of California Press.Search for more papers by this author Alexander F. Skutch, Alexander F. Skutch Alexander F. Skutch, a botanist and naturalist, has spent the past forty-seven years living on a remote farm in Costa Rica. This essay is adapted from his forthcoming Nature Through Tropical Windows. Copyright ©1983 by the regents of the University of California. To be published by the University of California Press.Search for more papers by this author First published: November‐December 1983 https://doi.org/10.1002/j.2326-1951.1983.tb02660.xCitations: 3 AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat Citing Literature Volume23, Issue6November‐December 1983Pages 18-21 RelatedInformation

Journal Article Migrant Birds in the Tropics Get access Migrant Birds in the Neotropics: Ecology, behavior, Distribution, and Conservation, edited by Keast Allen Morton Eugene S.. Smithsonian Institution Press, Washington, D.C. 1980, 576 p., illus. $27.50 (cloth) $15.00 (paper) (80-607031). Alexander F. Skutch Alexander F. Skutch Finca “Los Cusingos” El Quizarra San Isidor del General, Costa Rica, C.A. Search for other works by this author on: Oxford Academic Google Scholar BioScience, Volume 31, Issue 11, December 1981, Page 850, https://doi.org/10.2307/1308698 Published: 01 December 1981

SUMMARYAn adaptable and highly variable species, the Bright‐rumped Attila ranges across the whole breadth of tropical America and from sea level up to 6,000 or 7,000 feet. It inhabits not only rain forests and deciduous woodland but often enters plantations and clearings with scattered trees. It is usually seen alone, high in the trees.Its diet includes insects, small lizards, tiny frogs, fruits, and arillate seeds. Sometimes it catches small creatures from pasture grass or low weeds in plantations. Occasionally it forages with army ants.Both sexes deliver clear, melodious, far‐carrying songs or calls, in Costa Rica chiefly from February to April.A nest found in the Caribbean lowlands of Costa Rica was a bulky open cup, situated 32 inches above the ground on a little shelf in the deep embayment between two high plank buttresses of a great tree at the edge of a cacao plantation. In 1967 this nest held four nestlings that flew on 24 April. A new nest built in the very same site in the following year contained four newly laid eggs on 13 March. They resembled the eggs of certain American flycatchers more than those of other cotingas.Only the female incubated. During an all‐day watch, her sessions ranged from 63 to 111 minutes, her recesses from 13 to 60 minutes, and she covered her eggs for 67% of the time. When she returned to her nest she was escorted closely by her mate. While sitting, she often sang a long‐drawn, subdued nest song, or in a louder voice answered her mate with a song similar to his. The incubation period was no less than 18 days.Newly hatched nestlings had flesh‐coloured skin shaded by dark grey down that was abundant for a passerine. The interior of the mouth was bright orange‐yellow. Even before they were feathered, these nestlings gave weaker‐voiced imitations of their parents' calls or songs, and soon they could reproduce much of the adults' repertoire. The nestling period was about 18 days.Only the female brooded the nestlings, but the two parents took about equal parts feeding them, chiefly with small lizards, tiny frogs, and a few insects, brought one at a time in the parents' bills.The parents defended the territory around their nest, vigorously attacking intruders of their own species.

IbisVolume 112, Issue 1 p. 115-116 THE DISPLAY OF THE YELLOW-BILLED COTINGA CARPODECTES ANTONIAE Alexander F. Skutch, Alexander F. Skutch El Quizarri, San Isidro del General, Costa RicaSearch for more papers by this author Alexander F. Skutch, Alexander F. Skutch El Quizarri, San Isidro del General, Costa RicaSearch for more papers by this author First published: January 1970 https://doi.org/10.1111/j.1474-919X.1970.tb00085.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article. Volume112, Issue1January 1970Pages 115-116 RelatedInformation

SummarySome biologists have held that the rate of reproduction in birds tends to be adjusted to the average annual mortality; others, that it is limited only by the parents' ability to raise sturdy young. The latter theory, that of maximum reproduction, is likely to be true only if three related propositions are true:(1) that an increase of clutch size is more likely to occur than some other mutation affecting the rate of reproduction; (2) that a genotype with a wastefully high rate of reproduction can supplant a genotype with a more conservative but adequate rate; and (3) that an excessive rate of reproduction is not harmful to the species. None of these assumptions has been proved.In a population not obliged to employ its full reproductive potential to maintain itself at a favourable level, mutations which limit this potential may arise and persist. They may effect this limitation by means of:(i) reduction in clutch size; (ii) reduction in the number of broods; (iii) failure of the male to attend the nest, often followed by failure to form pairs; (iv) deferment of reproductive maturity; (v) developments in territorialism that limit the number of nesting birds or the number of progeny they can rear; (vi) restriction of nesting to traditional sites; and (vii) the time‐consuming construction of elaborate nests. These limitations of the rate of reproduction must be regarded as adaptive because, like other adaptations, they adjust the birds more perfectly to the conditions in which they live and reduce the stress to which they are subjected.In both tropical and temperate regions, species in which only the female feeds the nestlings have broods as large as species in which both parents feed them. It follows that the two parents are not rearing as many young as they could nourish.The view that hole‐nesting birds can rear larger broods than open‐nesters because their young develop more slowly, and require less food per capita per day, is untenable. Nestlings raised in holes and burrows gain weight about as rapidly as those in more exposed nests, but for safety they remain longer in their protected abodes. The larger broods of hole‐nesters evidently compensate for the difficulty of obtaining nest sites, which delays the breeding of some pairs and prevents that of others.Clutch size is by no means closely adjusted to the number of young the parents can raise. If given additional nestlings, some birds attend them adequately. In other species, young are rarely fledged from all the eggs. In many cases, asynchronous hatching is not, as has been claimed, an arrangement which permits the parents to adjust to a varying food supply the number of young that they rear. In many raptors, fratricide and cannibalism reduce the size of the brood, sometimes to a single nestling, regardless of the abundance of food.The more stable the environment, the more closely the reproductive rate tends to be adjusted to the mortality; the more a population is subject to catastrophic reductions, the more the rate will approach the maximum.Primarily, the reproductive rate is controlled by heritable characters, which can adjust the rate to a stable environment but rarely respond to short‐term fluctuations in external conditions or population density. The last fine adjustment of a population to its habitat is effected by processes that are density‐dependent:either density‐dependent regulation of the reproductive effort, or density‐dependent mortality of adults or young, or a combination of the two.The general evolutionary trend in the Metazoa is toward producing fewer offspring and taking better care of them. This would hardly be possible if the more prolific genotype always prevails over those which raise smaller families and in consequence can attend their young somewhat better. The regulation of the rate of reproduction is a unique evolutionary problem, because a mutation conferring greater fertility, although often detrimental to the species, tends to diffuse through it as no other harmful mutation can. Yet it is counteracted by many factors, chiefly ecological, which operate subtly and are more difficult to appreciate than the force of numbers.

SUMMARY In a park‐like area of 3.75 acres adjoining primary forest in Costa Rica, at an altitude of 2,500 ft., 83 nests, made by about 49 pairs of birds and two single females, were found in one year. Over a period of 20 years, 64 species were recorded as nesting in this same area. The difficulties of learning the actual rate of success of nesting birds are discussed, and it is concluded that, in view of the impossibility of assessing the effects of visits of inspection to nests in natural habitats, statements of breeding success are at best rough approximations of what happens in the absence of an observer. In the area of the census, nest‐success (the proportion of nests in which at least one egg was laid that produced at least one living fledgling) was 38–53% in four different years. During the four years 41 % of 208 nests were successful. Of 756 nests of 23 species of altricial birds of the Central American lowlands that build open or roofed nests in clearings and second‐growth, 37% were successful. When the computation is restricted to nests found before the last egg was laid (class B nests), 35% of 434 nests were successful, and 30% of 883 eggs produced living fledglings. In the neighbouring forests, nesting success was much lower, only 23.5% of 136 open or roofed nests producing at least one fledgling. Many forest birds increase their chances of success by entering neighbouring clearings to breed, but few open‐country birds build their nests in the forest. In both forest and clearings, hole‐nesting birds in Central America are much more successful than open‐nesters, as has been found also in the North Temperate Zone. A comparison of the results of a single season's observations in each of six Central American localities shows an increase of nesting success with altitude. In lowland Panama, the nest‐success was only 21%, in the Subtropical Zone of Costa Rica 53%, and in the altitudinal Temperate Zone of Guatemala 55%. The effect of altitude is complicated by differences in the amount of forest in the localities chosen for study, as well as by other factors difficult to assess. In both the tropics and the North Temperate Zone, nest losses are substantially higher in woodland than in man‐made habitats, evidently because there are fewer predators in the latter; but, even in clearings in Central America, nesting success was considerably lower than it was found to be in numerous studies in the North Temperate Zone. The difference may, however, reflect the greater “wildness” of the localities where the writer's studies were made, rather than a true contrast between tropical and temperate zone conditions. Snakes appear to be of the greatest single cause of nest losses in tropical America, but mammals, a few predatory birds, ants, and possibly even bats, destroy many eggs and young. Since small broods and heavy predation permit only a small annual contribution to the adult population, it is evident that, in order to maintain the species, adults must enjoy fairly long lives. Recent statistical studies support this theoretical conclusion.

Journal Article Life History Notes on Two Tropical American Kites Get access Alexander F. Skutch Alexander F. Skutch El Quizarrá, San Isidro del General, Costa Rica Search for other works by this author on: Oxford Academic Google Scholar The Condor, Volume 67, Issue 3, 1 May 1965, Pages 235–246, https://doi.org/10.2307/1365402 Published: 01 May 1965

THREE genera of birds, confined to the more southerly portions of the North American continent, are known collectively as the silky-flycatchers, which some ornithologists classify as a distinct family, the Ptilogonatidae, and others place with the waxwings and the Asiatic Hypocolius in the Bombycillidae. Of the three genera of silky-flycatchers, two are monotypic: Phainopepla nitens, the Phainopepla, which ranges from southwestern United States to the highlands of central Mexico; and Phainoptila melanoxantha, the Black-and-yellow Silky-flycatcher, which is confined to the high mountains of Costa Rica and neighboring parts of Panama'. The third genus, Ptilogonys, contains only two species, P. cinereus, the Gray Silky-flycatcher of the mountains of Mexico and Guatemala, and P. caudatus, the Long-tailed Silky-flycatcher, which is confined to high altitudes in Costa Rica and western Panama, approximately sharing the range of the Black-and-yellow Silky-flycatcher. As is to be expected from its geographical range, the best known, as to habits, of these birds is the Phainopepla of the southwestern United States, but even it has never been studied as thoroughly as have many other birds of temperate North America. For the Gray Silky-flycatcher there are a few scattered records of the discovery of nests and incidental observations by travelers and collectors. Of the Long-tailed Silky-flycatcher, even the nest seems to have been unknown to ornithologists until the present study was begun. Although, while studying Long-tailed Silky-flycatchers, I sometimes saw Black-and-yellow Silky-flycatchers, I learned nothing to fill the absolute void in my knowledge of their breeding habits.

Summary Over a wide geographical and altitudinal range, extending from sea level up to at least 7,000 feet in Costa Rica, the Blue‐diademed Motmot has adopted a great variety of habitats. It lives in pairs through most, if not all, of the year. Its food consists of a variety of insects, especially beetles, and small fruits. Pairs or trios apparently engaged in courtship hold pieces of green leaf or other fragments of vegetation in their bills, although they never take such material into their nests. Nesting burrows, up to 7 feet long, are usually dug from the side of a hole in the ground, rarely in an exposed bank where the entrance is conspicuous. Excavation begins in the wet season, from late August to October, and may continue for 21/2 months, chiefly in the late morning and early afternoon, when the soil is driest, at an average rate of little over one inch per day. Until the beginning of nesting at the end of the following dry season, the burrow is not used for sleeping and is rarely visited. In March or April, three white eggs are laid on the bare floor of the nest chamber. Both sexes incubate. One enters the burrow soon after noon and stays until the following dawn. After 15–30 minutes the mate enters and sits for about seven hours. The incubation period is about three weeks. The nestlings hatch completely naked. The nestling period is 29–32 (once 38) days. Brooding, even at night, ceases before the young are a week old, although they are still naked. Both parents bring them a variety of insects, chiefly beetles, small fruits, and occasionally a small snake, lizard, or bird. At one nest the rate of feeding increased up to the nestlings' nineteenth day, when each was fed 2·3 times per hour. After the nestlings' departure, neither parents nor young sleep in the burrow. The species is single‐brooded in Costa Rica.