We describe Phyllomyias weedeni, a new species of tyrannulet (Tyrannidae) from the Bolivian and Peruvian Andes. The species is morphologically and vocally most similar to widely allopatric P. fasciatus (Planalto Tyrannulet), but vocalizations recorded at the six localities from which it is known differ conspicuously and significantly from those of P. fasciatus, and differences in plumage and measurements are also apparent. Vocalization analysis further suggests that the P. fasciatus complex, which comprises three named subspecies, may consist of more than one biological species. Phyllomyias weedeni inhabits the upper canopy of humid and semi-humid foothill and lower montane forest within a narrow elevational range (700–1,200 m). It appears to prefer irregularly structured canopy dominated by small-leaved trees but has also been found in a mosaic of shade-coffee (Coffea spp.) plantations and remnant forest patches. It occurs at low densities, is apparently patchily distributed, and has an estimated extent of occurrence of ≤10,000 km². Its breeding population is estimated to be well below 10,000 mature individuals, and ongoing large-scale habitat conversion throughout much of the species' range could pose serious conservation problems. The new species thus qualifies as globally "vulnerable" under IUCN Red List Criteria. Further surveys are needed, especially in southeast Peru, to establish the extent of occurrence and population size of P. weedeni more precisely.

We examined variables influencing nest predation on the endangered Least Bell's Vireo (Vireo bellii pusillus) at three spatial scales to determine what nest-site, habitat, or landscape characteristics affect the likelihood of nest predation and to determine the spatial distribution of predation risk and the variables influencing it. We used MARK to calculate daily survival rates of Least Bell's Vireo nests and applied an information-theoretic approach to evaluate support for logistic regression models of the effect of habitat variables on predation risk. Analysis of data for 195 nests collected during 1999 and 2000 at the San Luis Rey River and Pilgrim Creek in southern California revealed no effect of fine-scale factors, including nest height, supporting plant species, and three measures of nest concealment, on the likelihood of predation. At the intermediate scale, distances to the riparian-habitat edge and to internal gaps in the canopy were unrelated to nest survival. Surrounding land-use type was a poor predictor of predation risk, with the exception of proximity to golf course–park habitat and wetland. Nests within 400 m of golf course–park were only 20% as likely to avoid predation as nests >400 m from this habitat, and nests near wetland were more than twice as likely to survive as nests distant from wetland. Spatially, predation appeared to be random throughout the site, with localized clustering evident in the vicinity of golf course–park and wetland. Our results suggest that the landscape may be the most appropriate scale at which to manage nest predation in this system.

During incubation, ground-breeding sandpipers such as Red Knots (Calidris canutus) create a warm, humid microclimate in the nest, conditions that favor the growth of feather-degrading bacteria present in their plumage. Just before incubation, the composition of waxes secreted by the uropygial gland of Red Knots and other sandpipers changes quickly and completely from a mixture of only monoesters to a mixture of only diesters. We hypothesized that the change in composition of the preen wax helps protect the plumage against feather-degrading bacteria. We tested the hypothesis by studying growth of the feather-degrading bacterium Bacillus licheniformis, which we found in the plumage of Red Knots. The removal of preen waxes from feathers resulted in faster bacterial degradation, confirming earlier findings that preen wax inhibits growth of feather-degrading bacteria. However, the degradation rate of feathers with preen wax based on diesters did not differ from that of feathers with preen wax based on monoesters. We suggest that preen waxes protect feathers by forming a physical barrier to microbes rather than through chemical properties of the waxes.

In many waterfowl species, females in better body condition have greater reproductive success than those in poor condition; thus, large-scale changes in body condition could influence species' population dynamics. Indices of annual productivity have decreased in Lesser Scaup (Aythya affinis), and the "spring condition" hypothesis (SCH) has been proposed to account for poor production and low populations in this species. We compared nutrient reserves of female Lesser Scaup and Ring-necked Ducks (A. collaris) collected during the breeding season at multiple sites in the Canadian boreal forest, the region where ~70% of both species breed and where they have had contrasting population trends for the past 25 years. Lesser Scaup tended to carry greater somatic lipid but slightly lower protein reserves than Ring-necked Ducks, after controlling for size. The proportion of females developing follicles was similar in both species, though Lesser Scaup initiated egg development later and exhibited less temporal variance in nesting date than Ring-necked Ducks. We also directly tested the SCH by comparing contemporary arrival and prebreeding body masses of Lesser Scaup with historical values at one boreal-forest site. However, body masses of Lesser Scaup collected in 2003–2004 were comparable to those of Lesser Scaup collected at Yellowknife, Northwest Territories, during 1968–1970. Overall, our results suggest that currently, body condition of boreal-breeding Lesser Scaup is relatively similar to that of Ring-necked Ducks and to historical levels for Lesser Scaup. Future studies of factors that limit recovery of Lesser Scaup should examine migration patterns and the effects of climate change on the timing of both energetic requirements in Lesser Scaup and food-resource availability.

Recent avian colonists to the West Indies have expanded their ranges through the archipelago in stepping-stone fashion, occupying virtually all of the available islands with suitable habitat. Consequently, gaps in the distributions of colonists can be interpreted as extinction events. One exception to this pattern is the weakly differentiated population of the Red-legged Thrush (Turdus plumbeus) on Dominica, removed by 600 km and many suitable islands from the nearest conspecific population. Mitochondrial DNA sequences show that the Dominican population is practically indistinguishable genetically from that of Puerto Rico. Large genetic distances among other adjacent island populations emphasize the recent derivation of the Dominican population from Puerto Rico, likely the result of human introduction.

Phylogenetic relationships among birds of prey in the subfamily Buteoninae are not fully established but are of particular interest because the Buteoninae constitute one of the largest accipitrid subgroups and include multiple species of conservation concern. Genera previously included within the Buteoninae are Buteo, Leucopternis, Buteogallus, Harpyhaliaetus, Busarellus, Parabuteo, Geranoaetus, Geranospiza, Ictinia, Rostrhamus, Kaupifalco, and Butastur. We analyzed representatives from all buteonine genera and most non-Buteo (i.e., "sub-buteo") species with >3,000 bases of nuclear and mitochondrial DNA and found non-monophyly for the nominal genera Buteo, Buteogallus, and Leucopternis. The Old World Lizard Buzzard (Kaupifalco monogrammicus) is not closely related to buteonine taxa but is sister to goshawks in the genera Melierax, Micronisus, and Urotriorchis. Another Old World genus, Butastur, is sister to the clade including all other buteonine genera mentioned above. Investigation of several "superspecies" complexes within the genus Leucopternis revealed non-monophyly for the four subspecies of White Hawk (L. albicollis). On the basis of mitochondrial data, L. a. albicollis forms a clade with L. polionotus, whereas L. a. costaricensis, L. a. ghiesbreghti, and L. a. williaminae form a clade with L. occidentalis. Among taxa included as outgroups, we found two species in the genus Circus to be clearly nested within a clade of Accipiter spp.

Estimating age-specific vital rates and determining which of them have the greatest influence on population trajectory is very useful for conservation and management of at-risk species. We created multistate capture–recapture models to provide estimates of age-specific variation in survival, recruitment, breeding propensity, and breeding success of Common Murres (Uria aalge) breeding at Southeast Farallon Island, California. Model-averaged age functions indicated that a "plateauing" (inverse age) function best characterized recruitment probability (transition from nonbreeder to breeder state) and breeding success (fledglings per pair). Adult and juvenile survival and breeding propensity were best modeled as constant with age. We modeled the population using an extended Leslie matrix and determined elasticity values for each of our estimated parameters to determine which have the greatest influence on population growth. Elasticities indicated that variation in adult survival had the greatest influence on population growth rate, but juvenile survival was also important. Increased juvenile survival since 1999, a period of cooler and more productive oceanic conditions, is probably largely responsible for the population growth observed during this period.

Few studies have investigated the vocal communication of ratites, and none has investigated the spectral and temporal structure of vocalizations of Apteryx, the only extant ratite genus in New Zealand. We describe the long-range vocalization (whistle call) and vocal behavior of male and female North Island Brown Kiwi (Apteryx mantelli). Spontaneous calling by seven pairs was recorded in the field over a one-year period. Call notes produced by males were tonal in nature; the fundamental frequency was ~1.5 kHz, with overtones reaching up to ~13.0 kHz. Call notes produced by females contained a series of tightly packed, poorly defined harmonics and consisted of a fundamental frequency of ~0.1 kHz, with overtones reaching ~7.0 kHz. The amplitude within notes of females was concentrated into two prominent formants. Some individuals of pairs exhibited duetting behavior that resulted in alteration of the inter-note interval after the onset of the call of their mate. Our findings draw attention to the uniqueness of the North Island Brown Kiwi's vocalizations, and we uncovered some unexpected structural features that call for further investigation.

Abundance estimation is central to avian ecology. For replicated counts, Royle (2004) developed a model to estimate abundance adjusted for detectability. Hitherto, it was unknown whether the same covariate was allowed to affect both abundance and detectability. This situation was disconcerting, because relationships between abundance and such covariates describing, for example, habitat, lie at the heart of ecology. I test this by simulation and provide additional guidelines on the model as well as code to fit it in a Bayesian mode of analysis. I simulated 1,000 data sets mimicking the Swiss breeding-bird survey "Monitoring Häufige Brutvögel" (three surveys in each of 268 quadrats). Elevation affected abundance negatively and detectability positively, resulting in a hump-shaped relationship between counts and elevation. I used WinBUGS to fit the model and estimate parameters, including quadrat-specific abundance and total abundance, across all 268 quadrats. For every parameter, the model recovered estimates that showed no indication of bias. The mean error in the estimated total population size across all quadrats was only 2%, whereas the summed maximum counts, a conventional abundance estimate, underestimated total population size by 43%. In contrast to maximum counts, the binomial mixture model revealed the true negative relationship between abundance and elevation. This model is a promising new alternative to capture–recapture or distance sampling methods to estimate bird abundance free of distorting effects of detectability. It has perhaps the fewest requirements, needing neither individual identification nor distance information to "convert" simple counts ("relative abundance") into estimates of true abundance. It ought to be seriously considered in future bird-survey schemes.

Summer breeding populations of Kittlitz's Murrelets (Brachyramphus brevirostris) have declined by 80–90% in southeastern Alaska during the past 25 years. Boating activities overlap considerably in space and time with Kittlitz's Murrelets in Glacier Bay, and disturbance could affect individuals by causing them to fly away from preferred foraging sites, thereby disrupting foraging bouts or resting periods. We observed the effects of vessel activity on Kittlitz's Murrelets at sea for each of three response variables (density, group size, and behaviors) in Glacier Bay. Response variables were characterized at three time-scales of inference: immediate (instantaneous response to vessel passage), short-term (response that persisted 30 min after vessel passage), and daily (response on days with different vessel traffic rates). Group size was not affected by vessel activity. By contrast, near-shore densities were suppressed temporarily by vessel passage but recovered within the day. Density effects did not persist at the daily time-scale and, therefore, did not result in persistent loss of foraging habitat for Kittlitz's Murrelets. Also, behavior was affected at both the immediate and daily time-scales, but not at the short-term time-scale, and may have affected Kittlitz's Murrelets by increasing the amount of time spent flying, which is energetically costly. Vessel passage caused a 30-fold increase in flight behavior (from 0% to 30%). Large and fast-moving vessels caused the greatest disturbance to Kittlitz's Murrelets, which has implications for management of vessel activity.

Understanding daily lipid-reserve changes in migrating wild birds is important for habitat assessment and species conservation. Plasma-lipid metabolites have been used to estimate rates of lipid accumulation or catabolism in small-bodied wild birds (<75 g), but this has not been validated for larger-bodied wild birds such as waterfowl. We developed an index for detecting whether individual birds accumulate or catabolize lipid reserves by regressing plasma-lipid metabolite levels (triglyceride and β-hydroxybutyrate) and known one-day mass changes (daily mass change) of 22 free-living Lesser Scaup (Aythya affinis; a larger-bodied species with typical mass range 600–1,000 g). Triglyceride and β-hydroxybutyrate predicted 75% of the variation in daily mass change (F = 28.85, df = 2 and 19, P < 0.001). Triglyceride was positively correlated (P = 0.029) with mass change, and β-hydroxybutyrate was negatively correlated (P < 0.001) with mass change (daily mass change = −54.49 11.82 [triglyceride] − 28.65 [β-hydroxybutyrate_log]). Our results indicate that triglyceride and β-hydroxybutyrate can estimate one-day changes in mass of free-living wild Lesser Scaup, which provides an index to daily changes in lipid reserves and should be useful for assessing quality of migration habitat.

We examined the influence of ecological and behavioral factors on breeding success of Ruddy-capped Nightingale Thrushes (Catharus frantzii) in contiguous primary- and secondary-forest habitats during the 2000–2003 breeding seasons in the Central Highlands of Chiapas, Mexico. Breeding density was higher in primary, undisturbed forest than in secondary forest with less understory vegetation. Nest-site selection was related to nest-concealment attributes (visibility, canopy cover, and shrub density) at the nest-site and patch levels. Nest-site selection was stronger in secondary forest, which indicates that preferred nest-site attributes were more limited in that habitat. Overall success per breeding attempt varied annually from 20% to 35%, with a higher mean annual success in primary forest (42%) than in secondary forest (19%). Daily nest survival rates were higher in primary than in secondary forest and varied with nest cover, lateral visibility, and density of ground epiphytes. The number of parental visits to nests was higher in primary than in secondary forest and lower for successful than for failed nests during incubation but did not vary with habitat or fate during the nestling stage. Female nest-attentiveness was higher in primary forest than in secondary forest throughout the nesting attempt and was higher for successful nests during the nestling stage only. Thus, Ruddy-capped Nightingale Thrushes showed habitat-specific breeding performance, with the primary-forest habitats (cloud forest, riparian) supporting higher densities and nesting success than secondary, disturbed habitats.

Macronutrient (protein, lipids, and carbohydrates) assimilation efficiencies of wild birds have rarely been studied, but they may be particularly important for estimating the optimal diet. We assessed experimentally the energy and macronutrient assimilation efficiencies of captive Snowy Plover (Charadrius alexandrinus) feeding on the polychaete ragworm Nereis diversicolor, a major natural prey for migratory shorebirds (Charadrii) along intertidal habitats worldwide. Overall, Snowy Plover consumed 8.64 ± 1.54 (SD) g of dry ragworms per day, and the apparent metabolizable energy was 136.59 ± 27.69 kJ·day⁻¹ (3.5–4.0 times the basal metabolic rate). Assimilation efficiencies were 80.04 ± 2.04%, 93.48 ± 1.08%, 84.75 ± 2.01%, and 89.23 ± 2.61% for energy, proteins, lipids, and carbohydrates, respectively. Macronutrient assimilation efficiencies were similar during early winter and premigration and between male and female Snowy Plover. Relatively high protein assimilation by Snowy Plover may be associated with their specialized high-protein diet.

Avian clutch size has been reported to show a poleward increase, a pattern that is well supported in landbirds but less so in waterbirds. We analyzed geographic variation in clutch and brood size among seven species of Nearctic herons and egrets (Ardeidae) over a latitudinal range spanning from 25° to 52°N. We included in the analysis data from 71 published references that reported information on both clutch and brood size. We found a strong and coherent latitudinal increase in clutch size in all species, but no unequivocal latitudinal variation in brood size. This resulted in a decreased index of productivity (brood size:clutch size ratio, excluding nest failures) with increasing latitude. In addition, we detected habitat-related variation in clutch size, which was, on average, smaller in salt-water than in freshwater habitats. The latitudinal decrease of the productivity index, which was not associated with latitudinal variation in nest-failure rates at either the clutch or brood stage, contrasts with previously proposed explanations for gradients in clutch size, which invoke latitudinal differences in seasonal variation of food abundance or nest-predation intensity. We suggest that factors other than those proposed in the case of landbirds may explain the latitudinal variation in clutch size in herons. In any case, our results suggest that herons may pay higher reproductive costs to obtain similar benefits when breeding at higher latitudes.

We studied nutrient-reserve dynamics of female Greater Scaup (Aythya marila) to quantify intraspecific strategies of nutrient acquisition for egg production, particularly in relation to the seasonal timing of reproduction (i.e., date of initiation of rapid follicle growth [RFG]). We collected female Greater Scaup on the Yukon-Kuskokwim Delta, Alaska, from arrival through clutch formation during the 2002 and 2003 breeding seasons, and we subsequently conducted standard proximate body-composition analysis. Endogenous lipid, protein, and mineral reserve levels did not decline during egg production. This result differs from most other nutrient-reserve studies of waterfowl, suggesting that female Greater Scaup rely on exogenous food resources, rather than endogenous nutrient reserves, to meet the energy and nutrient costs of clutch formation. Furthermore, endogenous nutrient-reserve levels did not decline with date of RFG initiation, which indicates that body condition at initiation of egg production was similar across the nesting season. We found evidence of nutrient-reserve thresholds for initiation of RFG, in that lipid, protein, and mineral reserves were smaller in nonreproductive than in reproductive females. In light of recent conservation concerns over declining North American scaup populations, our data contrast with nutrient-reserve dynamics described for Lesser Scaup (A. affinis).

Niceforo's Wren (Thryothorus nicefori) is a critically endangered songbird endemic to dry forests of the Chicamocha Valley in central Colombia. Discovered in 1946 and "red-listed" by the IUCN since 1988, Niceforo's Wren faces a threat of extinction because of its limited habitat range and increasing deforestation for agriculture and livestock. This species has been poorly studied, and its vocal behavior is yet undescribed. We provide the first description of the vocalizations of Niceforo's Wren, based on analyses of recordings from 29 individuals (more than half of all estimated living individuals of this species). We examined the fine structure of their songs, the pattern of solo and duet singing behavior, and the song repertoire size of males and females. Both sexes produce solo songs, coordinated vocal duets, and a variety of calls. Songs have a stereotyped syntax including one or more introductory syllables, a trill of rapidly repeated syllables, and a frequency-modulated terminal syllable. Males have a repertoire of at least 12–21 different song types, whereas females have a repertoire of at least 7–9. Both sexes sing solo songs with eventual variety. Male songs are more complex and have lower frequency characteristics, whereas female songs are shorter, with fewer syllable types and fewer syllable repeats. Duets involve mated pairs singing in a coordinated fashion using the same song types from their solo repertoires. Duets typically begin with a male song followed by a female song and show variable levels of complexity involving one to two songs given by each individual. Our results provide a foundation for monitoring Niceforo's Wrens and facilitating conservation of this critically endangered species.

It is widely accepted that tropical birds differ from temperate species in life-history traits and social behaviors, yet baseline ecological data are lacking for most tropical species and comparative studies often fail to control for phylogenetic influences. Within the Americas, the Yellow Warbler (Dendroica petechia) is ideal for such comparisons because its subspecies encompass a range of life-history strategies; the subspecies include long-distance migrants, temperate–tropical migrants, and tropical residents. We collected baseline data on the breeding ecology of Mangrove Warblers (D. p. bryanti) from southern Mexico (2001–2003) and compared their life-history traits with those of temperate and other tropical subspecies using existing data. Mangrove Warblers actively defended territories year-round during both nonbreeding and breeding seasons. The timing of breeding varied by year, and clutch size averaged 2.9 ± 0.5 [SD] eggs, with both a median and a mode of 3 eggs. Annual estimates of nesting success ranged from 18% to 33%, and nest depredation was the primary cause of nest failure. Annual survival was significantly higher for males (0.65) than for females (0.52) and, given our data, did not vary by age or year. On the basis of a comparative analysis of life-history data from published studies on the Yellow Warbler subspecies complex, we found that most life-history traits differed between tropical and temperate latitudes. Specifically, compared with temperate Yellow Warblers, Mangrove Warblers exhibited longer breeding seasons, smaller clutch sizes, longer incubation and nestling periods, lower nesting success, higher rates of nest depredation, and higher annual adult survival rates.

Certain contaminants alter normal physiological function, morphology, and behavior of exposed organisms through an endocrine mechanism. We evaluated how the herbicide linuron, an endocrine-active compound, affects physiological parameters and secondary sex characteristics of the American Goldfinch (Carduelis tristis). When administered at relatively low doses (control, 1.0, 4.0, and 16.0 μg linuron per gram of body mass per day), linuron delayed prealternate molt progression in a dose-dependent manner. At the high dose level, linuron exposure lowered hematocrit and female plasma thyroxine concentrations and increased body mass. Neither plasma testosterone concentrations nor the color of plumage or integument of birds in the treatment groups were different from those of the control group. Overall, the physiological effects that were measured suggested disruption of thyroid function. These results highlight the importance of continual monitoring of avian populations for potential effects of exposure to pesticides and other chemicals at sublethal concentrations.

Since 2004, we have surveyed birds in the southwest Guangxi Zhuang Autonomous Region of China. Many times during February, July, and October 2005 and January 2006, we observed, in Nonggang Natural Reserve of Guangxi, a species in the family Timaliidae that has never been recorded before in China or Southeast Asia. Nonggang Natural Reserve is located in the Sino-Vietnamese border region at 22°13′–22°34′N, 106°42′–107°05′E, 18 km southeast of the Vietnamese border. On 21 January 2006, we captured two individuals. Subsequent investigation showed that the specimens belonged to a previously undescribed species, which we designate Stachyris nonggangensis, the Nonggang Babbler.

Food resources available to diving ducks wintering on the Great Lakes have changed dramatically since the introduction of dreissenid mussels (Dreissena bugensis and D. polymorpha). We investigated the diets of Buffleheads (Bucephala albeola), Common Goldeneyes (B. clangula), and Long-tailed Ducks (Clangula hyemalis) during winter, 2002–2004, on northeastern Lake Ontario and determined the levels of dietary overlap. Dietary niche-breadth values were low, and dietary overlap values (prey size and type) were high for all species. Ducks primarily consumed high-quality, energy-dense prey (Amphipoda, Chironomidae), which were abundant. Our results highlighted three patterns: (1) dreissenid mussels constituted 85% of the macroinvertebrate community in Lake Ontario but were consumed in relatively low amounts during winter, (2) foods of high energy-density such as Amphipoda and Chironomidae were likely abundant enough for ducks to selectively feed on them, and (3) some constraint caused ducks to select energy-dense prey instead of the most available items (dreissenid mussels). Although the abundance of prey may have allowed numbers of diving ducks to increase in the past few decades on the Great Lakes, the long-term implications of high levels of dietary overlap among diving ducks is relatively unknown and warrants continued monitoring.

We evaluated associations between the Conservation Reserve Program (CRP) and Ring-necked Pheasant (Phasianus colchicus) populations by modeling Breeding Bird Survey (BBS) counts of Ring-necked Pheasants during 1987–2005 along 388 routes in nine states. Ring-necked Pheasant counts were analyzed as overdispersed Poisson counts in a Bayesian hierarchical model estimated with Markov-chain Monte Carlo methods. This approach allowed for simultaneous estimation of the relationships between BBS counts and various habitat types, including CRP habitat types, for multiple regions and across the entire study area. The predictor variables included a time trend and percentages of major National Land Cover Dataset 1992 and CRP habitat types within a 1,000-m buffer around each route, along with other patch metrics. The deviance information criterion was used as a guide to help identify the most parsimonious model. We estimated that, on average, there was a positive association of Ring-necked Pheasant counts with the amount of CRP herbaceous vegetation within a 1,000-m buffer around a route. The analysis can be repeated periodically to model changes in Ring-necked Pheasant populations associated with new CRP enrollments and expiration of existing CRP contracts on a large scale. Our methodology can also be extended to other species and to other states and regions.

As the human population and tourism increase in the Galápagos Islands, increased poultry production raises risks of pathogen spillover into native avian populations. Here, we characterize the disease risks to Galápagos avifauna of different types of poultry farming by comparing health status and serosurvey results between broiler and backyard chickens (Gallus gallus domesticus). Backyard chickens were more frequently diseased than broilers, and were more likely to be seropositive for several pathogens (Mycoplasma gallisepticum, infectious laryngotracheitis virus, infectious bronchitis virus, avian reovirus, and Marek's disease virus). Seroprevalence for other pathogens (avian paramyxovirus-1, infectious bursal disease, avian encephalomyelitis virus, and avian adenovirus) was relatively high among all chickens. Preliminary serological results from wild birds revealed no evidence of previous exposure to these diseases, which suggests that transmission of disease from poultry to wildlife is currently not detectable with the sample sizes and tests employed, and that wildlife are likely not the source of exposure to poultry. Our results suggest that backyard chickens may pose a greater threat to Galápagos avifauna because they are more likely to be infectious, have a high seroprevalence for numerous pathogens, and interact directly with wild birds or wild bird habitat, with no biosecurity measures employed. The broiler industry has greater potential for importation of pathogens into the islands and indirect transmission of diseases to wildlife (e.g., through use of poultry litter on agricultural land). Regulatory and management decisions should focus on minimizing the poultry–wildlife interface, reducing infectious diseases in backyard chickens, and preventing importation of poultry diseases.

Recent studies have suggested that bone alkaline phosphatase (ALP) may be a valuable indicator of skeletal development in wild birds. However, the information about age-related dynamics of ALP isoforms in passerines is very scanty. We examined age-related changes in the activity of bone ALP and liver ALP and tested the applicability of these isoenzymes as indicators of chick maturity in randomly selected nestlings of a small passerine bird, the Great Tit (Parus major). Bone ALP activity was elevated in the middle of the nestling period (day 8), when skeletal growth is assumed to be most rapid, and declined significantly during the prefledging stage (day 15 posthatch). Bone ALP activity at this age was positively and highly significantly related to the overall duration of nestling period and negatively and less significantly related to wing length and body mass. All three morphological traits of the 15-day-old nestlings were nearly significantly negatively correlated with the duration of the nestling period. Liver ALP activity neither changed with nestling age nor was related to nestling morphology. We suggest that prefledging activity of bone ALP is a more reliable indicator of nestling maturity than traditionally used morphological measurements.

The Queen Charlotte Islands (QCI), British Columbia, have many putative endemic avian subspecies. We evaluated four species—Northern Saw-whet Owl (Aegolius acadicus), Hairy Woodpecker (Picoides villosus), Steller's Jay (Cyanocitta stelleri), and Pine Grosbeak (Pinicola enucleator), each with a phenotypically described endemic subspecies from QCI—for uniqueness, conservation concern, and management. The Chestnut-backed Chickadee (Poecile rufescens), with no endemic subspecies from QCI, was included for comparison. We hypothesized that the four endemics would have similar phylogeographic patterns of genetic divergence and coalescence between QCI and possible source populations, because they may share a glacial-refugium history. Cytochrome b was sequenced for all species from Alaska, Washington, and QCI. The four species with endemic phenotypes from QCI had significant genetic divergence from nearby conspecific populations, though variation in divergence times indicated varying colonization histories. Given the corroboration between morphological and genetic evidence for derived populations from QCI, the four endemic subspecies exhibit hallmarks of being evolutionarily significant units (ESUs) and, at the least, should be considered separate management units (MUs), distinct population segments (DPSs), or designatable units (DUs). This is reflected in existing subspecific nomenclature, which our genetic results support. Chestnut-backed Chickadees had genetic differentiation in southeast Alaska as a separate MU but no significant differentiation in QCI. Our results indicate that QCI has been an important area for the generation of avian diversity below the species level and that it is an important area for the conservation and management of birds in northwestern North America.

Seed availability in the algarrobal of the Monte desert, Argentina, as in other deserts, is highly heterogeneous at small scales and is associated with vegetation structure. Granivores are expected to use space selectively (within the capacities of their foraging techniques), resulting in a heterogeneous effect on the seed bank. First, we describe the foraging repertoire of granivorous birds in the algarrobal to develop predictions about their expected use of space. Although the granivory guild as a whole tracked the temporal availability of seeds, species within the guild differed in foraging behavior and seasonal changes. We assessed selection of space by foraging birds through a two-scale bird-centered analysis, comparing the distributions of used and available sites. Granivorous birds, considered as a guild, used the whole range of available microsites, though as a result of an aggregation of contrasting partial patterns. Microsites with more cover of shrubs, grasses, and litter were preferred for predispersal consumption, which is consistent with the frequent technique of attacking grasses from low woody perches. By contrast, use of microsites for postdispersal consumption did not differ from random, which suggests that there are no safe microsites for seeds in this habitat. At a larger scale not particularly related to heterogeneity in food availability, a selective pattern was clearer: birds avoided mesosites with low shrub and litter cover, far from trees. In conclusion, patterns are not straightforward and depend on considerations of spatiotemporal scale and species-specific characteristics. Even when predictions seemed clear-cut and were tested with proper scale and target-group, granivorous birds did not select space according to environmental clues of food abundance.