Publications

evolutionary origin of cardiac malformations.	the author has proposed in previous publications that isolated cardiac malformations have an evolutionary origin. this is partly supported by the fact that isolated cardiac malformations found in humans occur also in other placental mammals as well as in birds. external gross examination of the heart in just over 5,000 birds was carried out during a 3 year period. anomalies included one instance of duplicate hearts, two specimens in which no heart could be identified and in a fourth, a yellow-ru ...	1988	3047192
dietary modulation of intestinal hydrolytic enzymes in yellow-rumped warblers.	many birds exhibit seasonal switches in diet and thus alter the nutrients predominating their food intake. we tested for dietary modulation of small intestine (si) enzymes in yellow-rumped warblers, a species for which such diet changes are well documented. birds were fed three diets formulated from either fruit, insect, or seed. we predicted that si carbohydrases and peptidases would be modulated in direct correlation with relative levels of dietary carbohydrate and protein, respectively. amino ...	1995	7653664
is diet shifting facilitated by modulation of intestinal nutrient uptake? test of an adaptational hypothesis in yellow-rumped warblers.	yellow-rumped warblers (dendroica coronata) are one of many avian species that change their diet seasonally. using them, we tested the predictions that uptake of d-glucose and the amino acid l-leucine will increase as dietary levels of carbohydrate and protein, respectively, are increased and that mediated uptake capacity of the entire small intestine will match nutrient loads from daily food intake. birds were fed three semisynthetic diets, formulated from fruit, insects, or seeds, for 7 d. med ...	2013	9231394
a test for passive absorption of glucose in yellow-rumped warblers and its ecological implications.	in an earlier study, we found that yellow-rumped warblers had in vitro active uptake rates of d-glucose that were only a few percent of the glucose absorption rate achieved at the whole-animal level. here we used a pharmacokinetic technique to test whether a substantial amount of sugar can be absorbed passively. we used yellow-rumped warblers (dendroica coronata), known for their seasonal frugivory, freely feeding on a synthetic mash formulated with naturally occurring concentrations of d-glucos ...	2013	9231411
an experimental test of dietary enzyme modulation in pine warblers dendroica pinus.	modulation of gut function is important in an ecological and evolutionary context because it likely determines what food items an animal can and cannot eat. we examined how diet affects activity of digestive enzymes in an omnivorous bird, the pine warbler (dendroica pinus). pine warblers were fed insect-based, fruit-based, and seed-based diets for approximately 54 d. we then measured activity of amylase, maltase, sucrase, aminopeptidase-n, trypsin, chymotrypsin, carboxypeptidase a, carboxypeptid ...	1999	10521325
changes in patterns of corticosterone secretion concurrent with migratory fattening in a neotropical migratory bird.	several studies on free-living birds have shown a change in corticosterone secretion (elevated baseline levels and a reduced corticosterone response to stress) during migration. it was not known, however, if this change was concurrent with the development of migratory condition or if it was an independent response to unknown environmental stressors experienced by the birds prior to capture. in this study, a neotropical annual migrant, the yellow-rumped warbler (dendroica coronata), held under co ...	1999	10525361
lead toxicosis and trace element levels in wild birds and mammals at a firearms training facility.	in may 1999, lead poisoning was diagnosed in a yellow-rumped warbler (dendroica coronata) and a gray squirrel (sciurus carolinensis) found at the federal law enforcement training center (fletc), glynn county, ga, based on detection of 6.2 and 90.0 ppm wet weight (ww) lead in the liver of the warbler and squirrel, respectively. from october 21--26, 1999, 72 wild animals (37 mammals and 35 birds), comprised of 22 different species, were collected from a 24-ha area surrounding the fletc outdoor fir ...	2001	11462145
digestive response to restricted feeding in migratory yellow-rumped warblers.	smaller guts and slow initial mass gains at stopover sites have led to the idea that digestive physiology limits refueling rates in migrating birds. we tested the digestive-limitation hypothesis in yellow-rumped warblers using food restriction to simulate infrequent feeding during migration, which may cause a reduction in alimentary tract mass. restricted birds had small intestine, pancreas, and liver masses 18%-22% lower than ad lib.-fed controls. total activities of sucrase, maltase, aminopept ...	2006	12177834
stable isotopes in breath, blood, feces and feathers can indicate intra-individual changes in the diet of migratory songbirds.	we used stable isotopes of c in breath, blood, feces and feathers to identify intra-individual changes in diet and the timescale of diet changes in free-living songbirds at a stopover site. because accurate interpretation of differences between the delta13c of breath, plasma, and red blood cells (rbcs) relative to diet requires knowing the turnover rate of c within them, we determined the rate of change of c in breath, plasma and rbcs for yellow-rumped warblers (dendroica coronata). half-lives o ...	2005	15586297
mercury concentrations in bicknell's thrush and other insectivorous passerines in montane forests of northeastern north america.	anthropogenic input of mercury (hg) into the environment has elevated risk to fish and wildlife, particularly in northeastern north america. investigations into the transfer and fate of hg have focused on inhabitants of freshwater aquatic ecosystems, as these are the habitats at greatest risk for methylmercury (mehg) biomagnification. deviating from such an approach, we documented mehg availability in a terrestrial montane ecosystem using a suite of insectivorous passerines. intensive and extens ...	2005	15931968
arsenic speciation in terrestrial birds from yellowknife, northwest territories, canada: the unexpected finding of arsenobetaine.	the surrounding area of yellowknife, northwest territories, canada, is known for naturally and anthropogenically elevated concentrations of arsenic. five bird species (gray jay [perisoreus canadensis], american tree sparrow [spizella arborea], dark-eyed junco [junco hyemalis], yellow-rumped warbler [dendroica coronata], and spruce grouse [dendragapus canadensis]) were collected from this area. their tissues were analyzed for total arsenic and for arsenic species, allowing us to report, to our kn ...	2005	16117124
effects of elemental composition on the incorporation of dietary nitrogen and carbon isotopic signatures in an omnivorous songbird.	the use of stable isotopes to infer diet requires quantifying the relationship between diet and tissues and, in particular, knowing of how quickly isotopes turnover in different tissues and how isotopic concentrations of different food components change (discriminate) when incorporated into consumer tissues. we used feeding trials with wild-caught yellow-rumped warblers (dendroica coronata) to determine delta15n and delta13c turnover rates for blood, delta15n and delta13c diet-tissue discriminat ...	2003	16228250
speciation and rapid phenotypic differentiation in the yellow-rumped warbler dendroica coronata complex.	the relative importance of the pleistocene glacial cycles in driving avian speciation remains controversial, partly because species limits in many groups remain poorly understood, and because current taxonomic designations are often based on phenotypic characteristics of uncertain phylogenetic significance. we use mtdna sequence data to examine patterns of genetic variation, sequence divergence and phylogenetic relationships between phenotypically distinct groups of the yellow-rumped warbler com ...	2007	17181728
west nile virus surveillance in east baton rouge parish, louisiana.	west nile virus (wnv) was detected for the first time in louisiana in the fall of 2001. surveillance data collected from east baton rouge parish in 2002 were examined to establish baseline data on wnv activity, to support the current design of disease surveillance programs, and to target vector control efforts in the parish. the first indications of wnv activity were from a dead northern cardinal collected in february and from a live male cardinal sampled on 14 march. in mosquito pools, wnv was ...	2007	17536365
a meta-analysis of bird responses to uniform partial harvesting across north america.	most data on the effects of partial-harvest silviculture (where live trees are purposely retained at the time of harvest) on birds come from one or a few discrete harvesting treatments. it is thus difficult to infer species responses across a continuous gradient of tree retention from individual studies. to quantify the levels of tree retention expected to produce specified changes in the relative abundance of individual species, we carried out a meta-analysis of 42 studies that examined the imp ...	2007	17883488
impacts of chronic anthropogenic noise from energy-sector activity on abundance of songbirds in the boreal forest.	the effects of human activities in forests are often examined in the context of habitat conversion. changes in habitat structure and composition are also associated with increases in the activity of people with vehicles and equipment, which results in increases in anthropogenic noise. anthropogenic noise may reduce habitat quality for many species, particularly those that rely on acoustic signals for communication. we compared the density and occupancy rate of forest passerines close to versus f ...	2008	18616740
incipient speciation despite little assortative mating: the yellow-rumped warbler hybrid zone.	hybrid zones between recently diverged taxa are natural laboratories for speciation research, allowing us to determine whether there is reproductive isolation between divergent forms and the causes of that isolation. we present a study of a classic avian hybrid zone in north america between two subspecies of the yellow-rumped warbler (dendroica coronata). although previous work has shown very little differentiation in mitochondrial dna across this hybrid zone, we identified two nuclear loci (one ...	2009	19624726
estimating the effects of detection heterogeneity and overdispersion on trends estimated from avian point counts.	point counts are a common method for sampling avian distribution and abundance. although methods for estimating detection probabilities are available, many analyses use raw counts and do not correct for detectability. we use a removal model of detection within an n-mixture approach to estimate abundance trends corrected for imperfect detection. we compare the corrected trend estimates to those estimated from raw counts for 16 species using 15 years of monitoring data on three national forests in ...	2009	20014578
hybrid origin of audubon's warbler.	several animal species have recently been shown to have hybrid origins, but no avian examples have been documented with molecular evidence. we investigate whether the audubon's warbler (dendroica auduboni), one of four visually distinct species in the yellow-rumped warbler complex, has originated through hybridization between two other species in this group, the myrtle warbler (d. coronata) and black-fronted warbler (d. nigrifrons). analysis of nuclear amplified fragment length polymorphism (afl ...	2011	21435063
increasing evidence of the role of gene flow in animal evolution: hybrid speciation in the yellow-rumped warbler complex.	in this issue of molecular ecology, brelsford et al. (2011) present strong evidence for a case of hybrid speciation within the yellow-rumped warbler complex. although homoploid hybrid speciation has now been documented in many animals (mallet 2007), it seems rare in tetrapods (mavárez & linares 2008) and it has barely even been mentioned in birds (price 2008). brelsford and colleagues thus present the first detailed molecular evidence suggesting that hybrid speciation can occur in birds. brelsfo ...	2011	21739625
migration, mitochondria, and the yellow-rumped warbler.	discordance between mitochondrial and nuclear dna has been noted in many systems. asymmetric introgression of mitochondria is a common cause of such discordances, although in most cases the drivers of introgression are unknown. in the yellow-rumped warbler, evidence suggests that mtdna from the eastern, myrtle warbler, has introgressed across much of the range of the western form, the audubon's warbler. within the southwestern united states myrtle mtdna comes into contact with another clade that ...	2014	24102562
physiological evidence that anthropogenic woodlots can substitute for native riparian woodlands as stopover habitat for migrant birds.	the ability to find sufficient high-quality stopover habitat is a crucial factor for successful migration for woodland migrant birds. woodland habitats are scarce in the northern prairie region of north america, and natural woodlands have been greatly reduced concurrent with the appearance of small anthropogenic woodlands on the landscape. landbird migrants use both natural and anthropogenic woodlands in this region as stopover habitats, but the relative quality of these two habitats is unknown. ...	2014	24457932
phenotypic flexibility of skeletal muscle and heart masses and expression of myostatin and tolloid-like proteinases in migrating passerine birds.	migrant birds require large flight muscles and hearts to enhance aerobic capacity and support sustained flight. a potential mechanism for increasing muscle and heart masses during migration in birds is the muscle growth inhibitor myostatin and its metalloproteinase activators, tolloid-like proteinases (tll-1 and tll-2). we hypothesized that myostatin, tll-1 and tll-2 are downregulated during migration in pectoralis and hearts of migratory passerines to promote hypertrophy. we measured seasonal v ...	2015	25585945
migration-induced variation of fatty acid transporters and cellular metabolic intensity in passerine birds.	because lipids are the main fuel supporting avian endurance activity, lipid transport and oxidation capacities may increase during migration. we measured enzyme activities, mrna expression and protein levels in pectoralis and heart for several key steps of lipid transport and catabolism pathways to investigate whether these pathways were upregulated during migration. we used yellow-rumped (setophaga coronata) and yellow (s. petechia) warblers and warbling vireos (vireo gilvus) as study species b ...	2015	26194862
seasonal dietary shifting in yellow-rumped warblers is unrelated to macronutrient targets.	dietary shifting, for example from insects to fruits, is a common mechanism used in migratory songbirds to accumulate fat to fuel migratory flights. we examined a potential underlying cause of dietary shifting in yellow-rumped warblers (setophaga coronata) by comparing energy and protein intake goals of birds during fall migration and winter. we offered captive warblers pairs of three diets differing in macronutrient composition in both the fall and winter. using the principles of the geometric ...	2016	26626955
amblyomma auricularium (ixodida: ixodidae) in florida: new hosts and distribution records.	previous published evidence for the occurrence of an exotic armadillo tick, amblyomma auricularium (conil), in florida is scant, but we found it is fully established and integrated into the state's tick fauna. we collected 11,192 specimens of this tick from naturalized nine-banded armadillos, dasypus novemcinctus l., and 14 other species of wild native mammals and birds in florida, while sampling statewide during 2004 through 2007. in all, we document its specific presence only in 14 contiguous ...	2017	28082640
test of a digestion optimization model: effect of variable-reward feeding schedules on digestive performance of a migratory bird.	birds on migration often alternate between feeding and nonfeeding periods, in part because food resources may be patchily distributed and in part because birds on migration may adopt a risk-prone foraging strategy characterized by selection of variable rather than constant food rewards. optimal digestion models predict that increases in intermeal interval like those encountered by some migratory birds should result in longer retention time of digesta and higher digestive efficiency if birds are ...	1998	28307928
migratory orientation in a narrow avian hybrid zone.	zones of contact between closely related taxa with divergent migratory routes, termed migratory divides, have been suggested as areas where hybrid offspring may have intermediate and inferior migratory routes, resulting in low fitness of hybrids and thereby promoting speciation. in the rocky mountains of canada there is a narrow hybrid zone between audubon's and myrtle warblers that is likely maintained by selection against hybrids. band recoveries and isotopic studies indicate that this hybrid ...	2017	28439469
seasonal and flight-related variation of galectin expression in heart, liver and flight muscles of yellow-rumped warblers (setophaga coronata).	galectins, a family of multifunctional glycan-binding proteins, are proposed as biomarkers of cellular stress responses. avian migration is an energetically challenging physical stress, which represents a physiological model of muscular endurance exercises. this study assesses change in galectin gene expression profiles associated with seasonal variation in migratory state and endurance flight in yellow-rumped warblers (setophaga coronata). bioinformatics analysis and real-time qpcr were used to ...	2017	28597244
linking the wintering and breeding grounds of warblers along the pacific flyway.	long-distance migration is a behavior that is exhibited by many animal groups. the evolution of novel migration routes can play an important role in range expansions, ecological interactions, and speciation. new migration routes may evolve in response to selection in favor of reducing distance between breeding and wintering areas, or avoiding navigational barriers. many migratory changes are likely to evolve gradually and are therefore difficult to study. here, we attempt to connect breeding and ...	2017	28904747
postbreeding elevational movements of western songbirds in northern california and southern oregon.	migratory species employ a variety of strategies to meet energetic demands of postbreeding molt. as such, at least a few species of western neotropical migrants are known to undergo short-distance upslope movements to locations where adults molt body and flight feathers (altitudinal molt migration). given inherent difficulties in measuring subtle movements of birds occurring in western mountains, we believe that altitudinal molt migration may be a common yet poorly documented phenomenon. to exam ...	2017	29043031
admixture mapping in a hybrid zone reveals loci associated with avian feather coloration.	identifying the genetic bases for colour patterns has provided important insights into the control and expression of pigmentation and how these characteristics influence fitness. however, much more is known about the genetic bases for traits based on melanin pigments than for traits based on another major class of pigments, carotenoids. here, we use natural admixture in a hybrid zone between audubon's and myrtle warblers (setophaga coronata auduboni/s. c. coronata) to identify genomic regions as ...	2017	29118129
dietary exposure to methylmercury affects flight endurance in a migratory songbird.	although there has been much speculation in the literature that methylmercury (mehg) exposure can reduce songbird fitness, little is known about its effects on migration. migrating songbirds typically make multiple flights, stopping to refuel for short periods between flights. how refueling at mehg-contaminated stopover sites would contribute to mehg bioaccumulation, and how such exposure could affect subsequent flight performance during migration has not been determined. in a dosing experiment ...	2018	29253830
a comparison of genomic islands of differentiation across three young avian species pairs.	detailed evaluations of genomic variation between sister species often reveal distinct chromosomal regions of high relative differentiation (i.e., "islands of differentiation" in fst ), but there is much debate regarding the causes of this pattern. we briefly review the prominent models of genomic islands of differentiation and compare patterns of genomic differentiation in three closely related pairs of new world warblers with the goal of evaluating support for the four models. each pair (macgi ...	2018	30187980
effects of experimental manipulation of hematocrit on avian flight performance in high- and low-altitude conditions.	despite widely held assumptions that hematocrit (hct) is a key determinant of aerobic capacity and exercise performance, this relationship has not often been tested rigorously in birds and results to date are mixed. migration in birds involves high-intensity exercise for long durations at various altitudes. therefore, it provides a good model system to examine the effect of hct on flight performance and physiological responses of exercise at high altitude. we treated yellow-rumped warblers (seto ...	2018	30266786
prevalence and diversity of haemosporidian parasites in the yellow-rumped warbler hybrid zone.	parasites can play a role in speciation, by exerting different selection pressures on different host lineages, leading to reproductive barriers in regions of possible interbreeding. hybrid zones therefore offer an ideal system to study the effect of parasites on speciation. here, we study a hybrid zone in the foothills of the rocky mountains where two yellow-rumped warbler subspecies, setophaga coronata coronata and s. c. auduboni, interbreed. there is partial reproductive isolation between them ...	2018	30386579
dietary polyunsaturated fatty acids influence flight muscle oxidative capacity but not endurance flight performance in a migratory songbird.	the migratory flights of birds are primarily fueled by fat; however, certain fatty acids may also enhance flight performance and the capacity to oxidize fat. the natural doping hypothesis posits that n-3 long-chain polyunsaturated fatty acids (pufa) increase membrane fluidity and aerobic and fatty acid oxidative enzymes in the flight muscles, which enables prolonged endurance flight. support for this hypothesis is mixed, and there is no empirical evidence for increased flight performance. we fed ...	2019	30624975
flight muscle protein damage during endurance flight is related to energy expenditure but not dietary polyunsaturated fatty acids in a migratory bird.	migration poses many physiological challenges for birds, including sustaining high intensity aerobic exercise for hours or days. a consequence of endurance flight is the production of reactive oxygen species (ros). ros production may be influenced by dietary polyunsaturated fatty acids (pufa), which, although prone to oxidative damage, may limit mitochondrial ros production and increase antioxidant capacity. we examined how flight muscles manage oxidative stress during flight, and whether dietar ...	2019	30824569
metabolic reduction after long-duration flight is not related to fat-free mass loss or flight duration in a migratory passerine.	migratory birds catabolize large quantities of protein during long flights, resulting in dramatic reductions in organ and muscle mass. one of the many hypotheses to explain this phenomenon is that decrease in lean mass is associated with reduced resting metabolism, saving energy after flight during refueling. however, the relationship between lean body mass and resting metabolic rate remains unclear. furthermore, the coupling of lean mass with resting metabolic rate and with peak metabolic rate ...	2020	32778563
measuring power input, power output and energy conversion efficiency in un-instrumented flying birds.	cost of flight at various speeds is a crucial determinant of flight behaviour in birds. aerodynamic models, predicting that mechanical power (pmech) varies with flight speed in a u-shaped manner, have been used together with an energy conversion factor (efficiency) to estimate metabolic power (pmet). despite few empirical studies, efficiency has been assumed constant across flight speeds at 23%. ideally, efficiency should be estimated from measurements of both pmech and pmet in un-instrumented f ...	2020	32796040