Breeding seabirds have been well studied but seabird ecology during the nonbreeding season is poorly understood because many species disperse far from breeding colonies to molt at sea. We characterized the timing of prebasic molt and postbreeding dispersal, described postbreeding dispersal movements, and estimated changes in body mass during molt for Marbled Murrelets (Brachyramphus marmoratus; Alcidae) in central California, 1999-2004. According to mark-recapture and at-sea surveys, 248-315 of 496-637 individuals (43-50%) used Ano Nuevo Bay, located immediately adjacent to nesting areas, for their prebasic molt in August-October. Long-distance dispersal (>= 100 km) from Ano Nuevo Bay by radiomarked Marbled Murrelets was low during breeding (9-13%, n = 46), but was greater for individuals radiomarked at the end of the breeding season (69-90%, n = 20). The mean dispersal dates were 18 May and 21 October for the breeding and postbreeding samples, respectively, and postbreeding dispersal occurred an average of two weeks after molt completion. Mean dispersal distances were 184 km and 256 km in the breeding and postbreeding periods, respectively. Of 12 long-distance dispersers, all moved south except one. Marbled Murrelets gained mass during molt (n = 184), except during a moderate El Nino event in 2002 when mass remained constant. However, birds did not take longer to molt in 2002, which suggests that individuals allocated more energy reserves to molt processes in that year. Apparently, sufficient prey resources were available in Ano Nuevo Bay for both basic metabolic requirements and the demands of molt, even when water was moderately warm.

Predator-prey relationships are often altered as a result of human activities. Where prey are legally protected, conservation action may include lethal predator control. In the Columbia River basin (Pacific Northwest, USA and Canada), piscivorous predators have been implicated in contributing to a lack of recovery of several endangered anadromous salmonids ( Oncorhynchus spp.), and lethal and nonlethal control programs have been instituted against both piscine and avian species. To determine the consequences of avian predation, we used a bioenergetics approach to estimate the consumption of salmonid smolts by waterbirds ( Common Merganser, California and Ring-billed Gull, Caspian Tern, Double-crested Cormorant) found in the mid-Columbia River from April through August, 2002-2004. We used our model to explore several predator-prey scenarios, including the impact of historical bird abundance, and the effect of preserving vs. removing birds, on smolt abundance. Each year, < 1% of the estimated available salmonid smolts (interannual range: 44 830-109 209; 95% CI = 38 000-137 000) were consumed, 85-98% away from dams. Current diet data combined with historical gull abundance at dams suggests that past smolt consumption may have been 1.5-3 times current numbers, depending on the assumed distribution of gulls along the reaches. After the majority (80%) of salmonid smolts have left the study area, birds switch their diet to predominantly juvenile northern pikeminnow (Ptychocheilus oregonensis), which as adults are significant native salmonid predators in the Columbia River. Our models suggest that one consequence of removing birds from the system may be increased pikeminnow abundance, which - even assuming 80% compensatory mortality in juvenile pikeminnow survival - would theoretically result in an annual average savings of just over 180 000 smolts, calculated over a decade. Practically, this suggests that smolt survival could be maximized by deterring birds from the river when smolts are present, allowing bird presence after the diet switch to act as a tool for salmonid-predator control, and conducting adult-pikeminnow control throughout. Our analysis demonstrates that identifying the strength of ecosystem interactions represents a top priority when attempting to manage the abundance of a particular ecosystem constituent, and that the consequences of a single-species view may be counterintuitive, and potentially counterproductive.

Approximately 60% of the 45 species of terns (Sternae) have an unusual form of wing molt in which a variable number of inner primaries and outer secondaries are replaced two or three times in a single year—a process that has been called "repeated molt." Although several hypotheses have been proposed for the maintenance of repeated molt, few data exist regarding potential selective forces that may have favored the evolution of this molt strategy, and there are no explanations for the high degree of interspecific variation in the extent of repeated molt. Preliminary investigations indicated that large terns tended to have less repeated molt than small terns and that the presence of repeated molt appeared to be associated with migratory behavior. We examined these initial findings by combining data from the literature, from examinations of museum specimens, and from a recent molecular phylogeny of the terns to perform phylogenetic-comparative tests. First, we used independent contrasts to verify that the association between large terns and less repeated molt was significant and not a result of shared ancestry. Second, we used tests for binary character association to evaluate the apparent link between repeated molt and migratory behavior. The results of these tests, along with reconstructions of ancestral states, led to a potential explanation for the origin of repeated molt, in which a tropical, sedentary ancestor gave rise to several lineages that spread to temperate areas and adopted a migratory life history. With this shift to a more seasonal regime came shortened breeding periods and perhaps more time for molt, which could have led to modifications of the ancestral molting strategy and the origin of repeated molt.

In birds, relative growth rates of morphological characters change in response to restricted food intake during development. Differential allocation of limited resources is hypothesized to reflect functional priorities for developing chicks. Body mass, wing, and flight feathers have been identified as potential priorities for seabird chicks. We used allometry to examine allocation in captive Common Murre chicks fed within a range of natural provisioning. During days 10-45 post-hatch, chicks were fed one of four diets that varied in biomass, energy content, and composition. Energy intake had a more profound effect on growth and development than diet composition; it significantly reduced absolute growth of body mass, manus, and tarsus. Between day 15 and day 20, allocation changed in all treatments: growth of manus was maintained at the expense of body mass. Chicks in more restricted treatments shifted allocation to manus at a lower body mass than those in less restricted groups, but subsequently allocated similarly. Wing loading was higher for chicks than for adult alcids, but scaled similarly. Growth of primary feathers was the most sensitive to small differences in diet composition. Our data also suggest that some changes in allocation may be ontogenetically determined rather than part of an adaptive response to reduced food intake.

Common Murres (Uria aalge; hereafter "murres") and Rhinoceros Auklets (Cerorhinca monocerata; hereafter "auklets") breed and forage sympatrically over much of their range. They have similar diets during the breeding season, which suggests that they partition prey during the breeding season by foraging (1) at different locations, (2) at different times of day, (3) at different water depths, (4) on different proportions of the same prey species, or (5) some combination of the four. We examined possible mechanisms of niche partitioning during late summer and fall in Puget Sound, Washington, in 1993-1996. Murres and auklets fed mainly on Pacific herring (Clupea pallasii, occurring in 74.2% and 48.1%, respectively, of gastrointestinal tracts with contents), Pacific sand lance (Ammodytes hexapterus; 45.8% and 62.3%), and salmonid (Oncorhynchus spp.) species (21.9% and 9.7%). Auklets also consumed considerable amounts of threespine stickleback (Gasterosteus aculeatus; 26.6%). Murres and auklets did not differ significantly (1) in their diet (between age classes or sexes of either species, or among years); (2) in mean lengths of Pacific herring (101 and 109 mm, respectively) and Pacific sand lance (82 and 86 mm) they consumed; or (3) in the mean depth (7-8 m) at which they were entangled in gill nets. Dietary diversity was low, with most gastrointestinal tracts containing only one or two prey species in both murres and auklets. Murres were caught and therefore presumably feed more frequently in the afternoon and evening; whereas anklets were entangled more often in early morning. We found differences between murres and auklets in the diel chronology of prey taken, which may partly explain how murres and auklets coexist during the breeding season and months thereafter, prior to auklet emigration from Puget Sound.

Previous reports have stated that Tufted Puffins (Fratercula cirrhata) lose all of their flight feathers simultaneously (or nearly so) during flight-feather molt and replace them in no apparent order. In contrast, we found that captive second-year (SY) Tufted Puffins (1) typically require 15 and 10 days to lose their primaries and secondaries, respectively, during their first flight-feather molt, and an average of 21 days to lose all of their remiges; and (2) replace their primaries in either of two discrete sequences. In 9 of 13 birds, primary molt began at the innermost primary, P1, and progressed distally to the outermost functional primary, P10. However, in the remaining four birds, primary molt began in the middle of the primaries (P5-P7) and progressed both distally to P10 and proximally toward P1. Before the proximal wave reached P1, a second wave of molt was initiated at P1 and progressed distally, typically replacing P2 and P3 before reaching the proximal wave. Such polymorphism in flight-feather molt sequence is rare in birds, having been reported previously only in a few passerine species. Secondary molt began about 13 days after onset of primary molt and finished at about the same time as primary molt, resulting in a total duration of flight-feather molt of similar to54 days and a flightless period of similar to40 days.

Howell et al. (2003) argue that the Humphrey-Parkes (H-P) system of molt terminology is flawed because it requires using traditional first prebasic molt as the starting point for plumage succession that results in noncorrespondence between nomenclature and presumed homology in first basic plumages. However, the H-P system does not require this. Second, they argue that plumage color can be a misleading criterion for evaluating plumage homologies. I show, however, that the timing and extent of molts, and thus their homologies, can de documented more accurately by using plumage color than by not doing so. Howell et al. (2003) propose a revised H-P system. To follow their system, one must accept their notion that no first-cycle molts are homologous with prebasic molts in subsequent molt cycles. However, this is not so as many species have a molt in their first cycle that is homologous to definitive prebasic molt. In addition, Howell et al.'s (2003) system does not offer any new or better criteria for identifying homologies than those suggested by Humphrey and Parkes (1959) and, thus, is not an improvement on the H-P system. First-cycle molts and plumages of most birds are poorly known. Therefore, we will not have sufficient data to determine whether new molts have been evolutionarily added to the first cycle, as suggested by Howell et al. (2003), until the molts of many more species of birds are studied. Further, these studies must be done on closely related species, not phylogenetically distant ones as proposed by Howell et al. (2003). Determinación de las Homologías Evolutivas de la Muda y el Plumaje: Un Comentario sobre Howell et al. (2003) Resumen. Howell et al. (2003) aducen que el sistema Humphrey-Parkes (H-P) de terminología para la muda es erróneo porque requiere utilizar la primera muda prebásica como el punto de partida para la sucesión del plumaje, lo que resulta en falta de correspondencia entre la nomenclatura y las presuntas homologías en los primeros plumajes básicos. Sin embargo, el sistema H-P no requiere esto. Segundo, ellos argumentan que el color de plumaje puede ser un criterio engañoso para evaluar las homologías del plumaje, pero yo demuestro que el momento y la extensión de las mudas, y por tanto sus homologías, pueden documentarse con mayor exactitud utilizando el color del plumaje que no haciéndolo. Howell et al. (2003) proponen un sistema H-P revisado que implica aceptar su noción de que ninguna de las mudas del primer ciclo es homóloga con mudas prebásicas de ciclos de muda subsiguientes. Sin embargo, esto no es así, pues muchas especies tienen una muda en su primer ciclo que es homóloga a la muda prebásica definitiva. Adicionalmente, el sistema de Howell et al. (2003) no ofrece criterios nuevos o mejores para identificar las homologías que aquellos sugeridos por Humphrey and Parkes (1959), por lo que no representa un mejoramiento del sistema H-P. Las mudas y los plumajes del primer ciclo de la mayoría de las aves son poco conocidos. Por lo tanto, hasta que no se estudie la muda en muchas más especies de aves, no tendremos suficientes datos para determinar si nuevas mudas se han adicionado evolutivamente al primer ciclo como Howell et al. (2003) sugirieron. Más aún, dichos estudios deben hacerse en especies estrechamente relacionadas, no en aquellas filogenéticamente distantes como Howell et al. (2003) propusieron.

Animals often exhibit individual variation in their behavioral responses to the same stimuli in the biotic or abiotic environment. To elucidate the endocrine mechanisms mediating such behavioral variation, we have been studying a species of lizard with two distinct male phenotypes. Here we document behavioral variation across years in one of the two male phenotypes of the tree lizard, Urosaurus ornatus, and present hormone data that support an endocrine mechanism underlying this behavioral variation. Nonterritorial male tree lizards appear to be nomadic rovers in some years and sedentary satellites in others, whereas territorial males are always territorial. This behavioral variation by nonterritorial males was correlated with environmental conditions. In environmentally harsher years (as assessed by rainfall), nonterritorial males appear to behave as nomads, whereas in more benign years they are more site-faithful. A between-year comparison of levels of corticosterone and testosterone for the two male phenotypes supports a model for how hormones underlie the males' reproductive tactics, particularly the nonterritorial males' behavioral plasticity. In an environmentally harsher (drier) year, both types of males had higher corticosterone levels than in a milder (wetter) year, but only nonterritorial males had lower testosterone in the relatively harsher year. We propose that disruptive selection for individual variation in hormonal responses to environmental cues may be a common mechanism underlying the evolution of alternative male reproductive tactics in this and other species.

The coastal states of western North America and Mexico are home to a population of Caspian Terns (Sterna caspia) that are geographically disjunct and probably genetically isolated front other Caspian Terns in North America. About 74%, of these birds nest at a single colony, East Sand Island, near the mouth of the Columbia River between Washington and Oregon. It is estimated by others that When the terns nested in 1998 on Rice Island. 26 km further east in the Columbia River estuary, they consumed Steelhead smolts (Oncorhynchas mykiss), Coho smolts (O. ksutch), and spring/summer Chinook smolts (O. tshawytscha) that reached the Columbia River estuary, thus involving species listed under the United States Endangered Species Act. In addition, because such a large percentage of the west coast population breeds at a single colony there is concern that a natural or anthropogenic event at this colony may adversely impact the entire Population. As a result, many federal, state, tribal and private natural resource managers are trying to develop a management plan to disperse a fraction of these terns front East Sand Island to other historic and/or newly created nesting sites throughout western North America. Among factors to be considered, managers must assess the potential impact that terns Would have on fisheries, especially salmonids, at potential relocation sites before attempts are made to relocate the birds. This study documents the diet of terns in one prospective relevation area. Commencement Bay, Washington, Relative abundance of prey species, including salmonids, delivered to the colony by adults differed significantly front month to month during the breeding season, but overall terns brought all average of 52% juvenile salmonids back to the colony, a higher percentage of salmonids than are consumed by terns on East Sand Island. Therefore, we conclude that Commencement Bay may not be an appropriate relocation site for Caspian Terns. Received 2 October 2001, accepted 2 December 2001.

The decline of many species of Neotropical migrants has prompted increased research on their ecology on their breeding and wintering grounds. However, studies of their ecology during migration are relatively few. Despite documentation of molt-migration in at least six Neotropical passerine species, this phenomenon has been ignored in current conservation strategies for Neotropical migrants. In this review paper, we suggest that molt studies need to be done as a way to refine and improve conservation plans for Neotropical migrants. We identify three important questions that merit further study: (1) which Neotropical migrant species undergo flight feather molt at migratory-stopover sites; (2) where are molt-migration stopover sites geographically located; and (3) why are these sites preferred as stopover sites during molt? Finding answers to these questions will allow us to protect molt staging areas occupied by Neotropical migrants during migration as many wetland and nearshore oceanic habitats have been protected for molting waterfowl, shorebirds, and seabirds.

Abstrac tManagement proposals to reduce Caspian tern (Sterna caspia ) predation on juvenile salmonids (Oncorhynchu sspp.) in the Columbia River estuary include relocating some terns from the large colony in the estuary to several smaller colonies outside the Colum bia River basin. The welfare of other listed or beleaguered salmonid stocks has been a primary concern in areas considered for restoration of Caspian tern colonies, demon strating a need for empirical evidence on the effects of tern predation on fisheries prior to restoration of permanent colonies. The main objectives of this study were to determine 1) whether Caspian terns would readily use a barge as a temporary nesting site and 2 ) whether tern diet composition and productivity data could be collected at the barge. A small, sand-covered barge equipped with tern decoys and sound systems was anchored in Commencement Bay, Washington in 2001. Approximately 388 tern nests were init i ated on the barge in a 17-day time period. We monitored diet composition at the barge site by direct observation of fish ( n =1,097) in the bills of nesting adults. Tern diets du r ing May were 65% juvenile salmonids; marine forage fishes comprised the remainder o f the diet. Predation on tern eggs by glaucous-winged gulls (Larus glaucescen s) was fre quently observed during the first 10 days following the onset of egg laying; however, pre dation declined once incubating terns were densely packed on the barge. This study demonstrated that terns might rapidly colonize a barge and that diet composition and productivity data can be collected at the barge site. Barges may be used to asses s prospective colony restoration sites; however, these efforts must be carefully conceived and coordinated with resource managers to avoid new resource management conflicts .

Abstract We sequenced the complete mitochondrial cytochrome-b gene (1,143 nucleotides) for representatives of each species in the cardinalid genera Passerina (6 species), Guiraca (1 species), and Cyanocompsa (3 species), and used a variety of phylogenetic methods to address relationships within and among genera. We determined that Passerina, as presently recognized, is paraphyletic. Lazuli Bunting (P. amoena) is sister to the much larger Blue Grosbeak (Guiraca caerulea). Indigo Bunting (P. cyanea) and Lazuli Bunting are not sister taxa as generally thought. In all weighted parsimony trees and for the gamma-corrected HKY tree, Indigo Bunting is the sister of two sister groups, a “blue” (Lazuli Bunting and Blue Grosbeak) and a “painted” (Rosita's Bunting [P. rositae], Orange-breasted Bunting [P. leclancherii], Varied Bunting [P. versicolor], and Painted Bunting [P. ciris]) clade. The latter two species form a highly supported sister pair of relatively more recent origin. Uncorrected (p) distances for ingroup (Passerina and Guiraca) taxa range from 3.0% (P. versicolor–P. ciris) to 7.6% (P. cyanea–P. leclancherii) and average 6.5% overall. Assuming a molecular clock, a bunting “radiation” between 4.1 and 7.3 Mya yielded four lineages. This timing is consistent with fossil evidence and coincides with a late-Miocene cooling during which a variety of western grassland habitats evolved. A reduction in size at that time may have allowed buntings to exploit that new food resource (grass seeds). We speculate that the Blue Grosbeak subsequently gained large size and widespread distribution as a result of ecological character displacement.

We sequenced the complete mitochondrial cytochrome-b gene (1,143 nucle- otides) for representatives of each species in the cardinalid genera Passerina (6 species), Guir- aca (1 species), and Cyanocompsa (3 species), and used a variety of phylogenetic methods to address relationships within and among genera. We determined that Passerina, as presently recognized, is paraphyletic. Lazuli Bunting (P. amoena) is sister to the much larger Blue Gros- beak (Guiraca caerulea). Indigo Bunting (P. cyanea) and Lazuli Bunting are not sister taxa as generally thought. In all weighted parsimony trees and for the gamma-corrected HKY tree, Indigo Bunting is the sister of two sister groups, a blue (Lazuli Bunting and Blue Gros- beak) and a painted (Rosita's Bunting (P. rositae), Orange-breasted Bunting (P. leclancherii), Varied Bunting (P. versicolor), and Painted Bunting (P. ciris)) clade. The latter two species form a highly supported sister pair of relatively more recent origin. Uncorrected (p) distances for ingroup (Passerina and Guiraca) taxa range from 3.0% (P. versicolor-P. ciris) to 7.6% (P. cyanea- P. leclancherii) and average 6.5% overall. Assuming a molecular clock, a bunting radiation between 4.1 and 7.3 Mya yielded four lineages. This timing is consistent with fossil evidence and coincides with a late-Miocene cooling during which a variety of western grassland hab- itats evolved. A reduction in size at that time may have allowed buntings to exploit that new food resource (grass seeds). We speculate that the Blue Grosbeak subsequently gained large size and widespread distribution as a result of ecological character displacement. Received 25 October 1999, accepted 16 September 2000.

Common murres, Uria aalge, and rhinoceros auklets, Cerorhinca monocerata, were the 2 species entangled most frequently in sockeye and chum salmon gillnets in northern and central Puget Sound, Washington, in 1993 and 1994; they comprised more than 90% of all entangled seabirds. The ratio of entangled murres to auklets decreased about 5-fold from approximately 10:1 in 1993 to 2:1 in 1994. Most murres (63%) entangled were adults, whereas most auklets (63%) entangled were hatch-year birds. No significant differences in sex ratio could be detected among age classes of these species within or between fisheries (sockeye versus chum) or years, nor did observed sex ratios deviate significantly from an expected 1:1 sex ratio. During the sockeye fishery (early July through early September), 52% of subadult and adult murres were in breeding plumage, whereas 46% had begun molting flight feathers; by the chum fishery (late September through late November), only 18% were still molting flight feathers, whereas 77% had completed molting their flight feathers. All auklets were in breeding plumage having not yet begun flight-feather molt. No adult murres had visible incubation patches during the sockeye fishery. Because murres fledge from Oregon colonies at least a month earlier than they do from Washington colonies, adult murres from Oregon grow their incubation patches back at least a month earlier as well; this suggests that at least some entangled adult murres came from Oregon. Similarly, some hatch-year murres were entangled in Puget Sound before murre chicks fledged from Washington (or more northerly) colonies, again indicating that at least some hatchyear murres fledged from Oregon colonies.