Bullock's Oriole Research Articles

Revisiting the Baltimore-Bullock's Oriole hybrid zone reveals changing plumage colour in Bullock's Orioles.

Hybrid zones are dynamic areas where populations of two or more interbreeding species may change through an influx of novel genetic material resulting from hybridization or selection on standing genetic variation. Documenting changes in populations through time, however, is challenging because repeated samples are often missing or because long-term storage can affect trait morphologies, especially colour traits that may fade through time. We document a change in carotenoid-based orange breast feathers of Bullock's Orioles (Icterus bullockii) from the Great Plains hybrid zone, USA. Contemporary Bullock's Orioles are more orange than historic individuals from the same location sampled approximately 60 years ago. Spectrophotometry revealed that contemporary Bullock's Orioles resemble orange colour profiles of Baltimore Orioles (I. galbula), the species with which they hybridize. Fading or changes in diet hypotheses do not appear to explain the shift in colour we report for Bullock's Orioles. We propose that these changes in colour are facilitated through introgression with Baltimore Orioles, and favoured by females that choose brighter, more orange males. Our study highlights the long memory of natural history collections and how they offer new insights to the dynamic roll of hybrid zones in trait evolution between interacting species.

Conditions on the Mexican moulting grounds influence feather colour and carotenoids in Bullock's orioles (Icterus bullockii)

Carotenoid‐based plumage coloration plays a critical role for both inter‐ and intrasexual communication. Habitat and diet during molt can have important consequences for the development of the ornamental signals used in these contexts. When molt occurs away from the breeding grounds (e.g., pre‐alternate molt on the wintering grounds, or stopover molt), discerning the influence of habitat and diet can be particularly important, as these effects may result in important carryover effects that influence territory acquisition or mate choice in subsequent seasons. Several species of songbirds in western North America, including the Bullock's oriole (Icterus bullockii), migrate from the breeding grounds to undergo a complete prebasic (post‐breeding) molt at a stopover site in the region affected by the Mexican monsoon climate pattern. This strategy appears to have evolved several times independently in response to the harsh, food‐limited late‐summer conditions in the arid West, which contrast strongly with the high productivity driven by heavy rains that is characteristic of the Mexican monsoon region. Within this region, individuals may be able to optimize plumage coloration by molting in favourable areas characterized by high resource abundance. We used stable isotope analysis (δ13C, δ15N) to ask whether the diet and molt habitat/location of Bullock's orioles influenced their expression of carotenoid‐based plumage coloration as well as plumage carotenoid content and composition. Bullock's orioles with lower feather δ15N values acquired more colorful plumage (orange‐shifted hue) but had feathers with lower total carotenoid concentration, lower zeaxanthin concentration, and marginally lower canthaxanthin and lutein concentration. Examining factors occurring throughout the annual cycle are critical for understanding evolutionary and ecological processes. Here, we demonstrate that conditions experienced during a stopover molt, occurring hundreds to thousands of kilometers from the breeding grounds, influence the production of ornamental plumage coloration, which may carryover to influence inter‐ and intrasexual signaling in subsequent seasons.

Rock wren transport in railroad boxcars

In 1956, and again in 1988, breeding pairs of rock wrens (Salpinctes obsoletus) were observed in Churchill, Manitoba, beyond their previously known breeding extent. It has been suggested that these and other vagrant rock wrens might have been accidentally transported in railroad boxcars. Alternative explanations include: 1) that rock wrens are prone to vagrancy during migration and dispersal, and 2) that the species is expanding its range via hydrographic or human-made corridors. I compiled northern and eastern vagrancy records from May 1898 through November 2015 for rock wrens and four other bird species with similar ranges. I calculated the distance of each sighting to the nearest railway and hydrographic features, compared these distances among species, and identified vagrant clusters. Rock wren vagrants were not significantly different from vagrants of lazuli buntings (Passerina amoena) or Bullock's orioles (Icterus bullockii) in their proximity to railways. Results suggest that vagrancy rates of rock wrens are similar to those of sage thrashers (Oreoscoptes montanus) and green-tailed towhees (Pipilo chlorurus), and vagrancy is likely driven by landscape factors rather than the use of railway corridors or accidental transport in freight cars. Proximity of vagrant rock wrens to lakes, reservoirs, rivers, and streams indicates that these and associated habitat features may act as travel and dispersal corridors.

Population response to environmental productivity throughout the annual cycle in a migratory songbird

AbstractEnvironmental factors affect migratory animal populations in every phase of their annual cycle and have significant impacts on breeding success and survival. The Breeding Bird Survey provides a long‐term database for examining population trends in North American birds, allowing us to examine large‐scale environmental factors that influence population abundance. We examined plant productivity as measured by normalized difference vegetation index (NDVI) over a 24‐year period from 1983–2006 in bird conservation regions (BCRs) that overlapped Bullock's oriole (Icterus bullockii) breeding, moult, and wintering ranges to ask whether plant productivity in 1 year influences population abundance in the subsequent breeding season. Bullock's orioles have a moult‐migration strategy, with a stopover moult in the Mexican monsoon region, which necessitates examining each stationary phase of the bird's annual cycle to understand the impacts of environmental factors on population abundance. Our results show increased breeding abundance in three (Great Basin, Coastal California and Shortgrass Prairies) of the six BCRs in which the species breeds following years with high NDVI values. We did not detect a response of breeding abundance to high NDVI values in the previous year in either the moulting region or in their primary over‐wintering area in central Mexico. Our results demonstrate that large‐scale annual variation in primary productivity on the breeding grounds can have an impact on breeding abundance in the following season, but further studies on migratory connectivity and on ecological mechanisms during the non‐breeding seasons are needed to understand why we did not detect an influence of productivity during these periods.

Extensive introgressive hybridization within the northern oriole group (GenusIcterus) revealed by three-species isolation with migration analysis

Until recently, studies of divergence and gene flow among closely-related taxa were generally limited to pairs of sister taxa. However, organisms frequently exchange genes with other non-sister taxa. The “northern oriole” group within genus Icterus exemplifies this problem. This group involves the extensively studied hybrid zone between Baltimore oriole (Icterus galbula) and Bullock's oriole (I. bullockii), an alleged hybrid zone between I. bullockii and black-backed oriole (I. abeillei), and likely mtDNA introgression between I. galbula and I. abeillei. Here, we examine the divergence population genetics of the entire northern oriole group using a multipopulation Isolation-with-Migration (IM) model. In accordance with Haldane's rule, nuclear loci introgress extensively beyond the I. galbula–I. bullockii hybrid zone, while mtDNA does not. We found no evidence of introgression between I. bullockii and I. abeillei or between I. galbula and I. abeillei when all three species were analyzed together in a three-population model. However, traditional pairwise analysis suggested some nuclear introgression from I. abeillei into I. galbula, probably reflecting genetic contributions from I. bullockii unaccounted for in a two-population model. Thus, only by including all members of this group in the analysis was it possible to rigorously estimate the level of gene flow among these three closely related species.

A Seven-Year Comparison of Relative-Abundance and Distance-Sampling Methods

AbstractWe used data from statewide surveys of riparian birds in Utah, 1992–1998, to compare relative-abundance and distance-sampling methods. By generating relative-abundance indices with point-count methods and density with point-transect sampling methods, we examined whether the assumptions underlying each method were met during field surveys for four bird species (Brown-headed Cowbird [Molothrus ater], Bullock's Oriole [Icterus bullockii], Warbling Vireo [Vireo gilvus], and Yellow Warbler [Dendroica petechia]). Point-count methods failed to reasonably meet the fundamental assumption of constant proportionality, with estimated detectability varying 3- to 5-fold despite the use of widely accepted and well-standardized methods. Population trends based on relative abundance were subsequently unstable, often varying in both magnitude and direction with the survey plot radius used (25 m, 50 m, or unlimited distance). Distance-sampling methods appeared to meet critical assumptions, were robust to assumption violations, allowed methodological self-assessment, and were demonstrably efficient in a large-scale, multispecies survey setting. Our data show surveys of birds without estimations of detectability are likely biased because the assumption of constant proportionality is violated to a degree that precludes strict inference and may confound trend analyses.

A SEVEN-YEAR COMPARISON OF RELATIVE-ABUNDANCE AND DISTANCE-SAMPLING METHODS

Abstract We used data from statewide surveys of riparian birds in Utah, 1992–1998, to compare relative-abundance and distance-sampling methods. By generating relative-abundance indices with point-count methods and density with point-transect sampling methods, we examined whether the assumptions underlying each method were met during field surveys for four bird species (Brown-headed Cowbird [Molothrus ater], Bullock's Oriole [Icterus bullockii], Warbling Vireo [Vireo gilvus], and Yellow Warbler [Dendroica petechia]). Point-count methods failed to reasonably meet the fundamental assumption of constant proportionality, with estimated detectability varying 3- to 5-fold despite the use of widely accepted and well-standardized methods. Population trends based on relative abundance were subsequently unstable, often varying in both magnitude and direction with the survey plot radius used (25 m, 50 m, or unlimited distance). Distance-sampling methods appeared to meet critical assumptions, were robust to assumption...

Extrapair paternity and variance in reproductive success related to breeding density in Bullock's orioles

Breeding density is predicted to influence the use of alternative reproductive strategies and may account for some of the variation in extrapair paternity rates found within and between avian species. By exploiting the extreme range of breeding densities occurring in a single, semicolonial population of Bullock's oriole, Icterus galbula bullockii, this study showed that, as predicted, both the number of nests containing extrapair nestlings and the mean proportion of extrapair nestlings in a brood increased with breeding density (high versus low breeding density: broods with extrapair nestlings: 62 versus 27%; mean: 48 versus 16%). As found in some other studies, extrapair paternity (both exclusion and assignment) significantly increased the variance in reproductive success among males. No difference was found in the mean reproductive success of males at different breeding densities. However, as predicted, the variance in reproductive success among males increased with breeding density. This study indicates that the distribution of individuals within a single population can lead to significant differences in the opportunity for sexual selection, and that density may be an important factor affecting variance in male reproductive success among populations.

Extra-pair paternity in relation to male age in Bullock's orioles

Single-locus minisatellite DNA profiling was used to assign paternity in a population of Bullock's orioles, Icterus galbula bullockii, and to determine the contribution of age to a male's success in obtaining extra-pair paternity. There was a very low rate of intraspecific brood parasitism (2/202 = 1.0% of chicks). Older adult males lost less within-pair paternity and gained more extra-pair fertilizations than did yearling subadult males. This resulted in adult males benefiting from an annual reproductive success more than double that of subadult males. Behavioural observations, used to determine the role of female choice in extra-pair copulations (EPCs), indicated that females actively participate in EPCs and that they prefer to obtain them from older males. While it was possible that females obtained EPCs as an insurance against the possible infertility of their social mate, the results of this study fit best with the hypothesis that females were attempting to obtain better-quality genes for their offspring by obtaining EPCs with older, better-quality males.

A nesting association between semi-colonial Bullock's orioles and yellow-billed magpies: evidence for the predator protection hypothesis

Mixed-species nesting associations have been reported for many birds. However, few studies have shown that one species specifically chooses to nest close to another in order to obtain a direct benefit and only two studies have managed to adequately test the predator protection hypothesis for such associations. Here we demonstrate a nesting association between Bullock's orioles (Icterus galbula bullockii) and yellow-billed magpies (Pica nuttalli). The evidence indicates that this is an active association in which, given a choice of suitable habitat areas in which to nest, orioles choose those areas that contain magpie nests. Oriole nests associated with magpie nests have a significantly reduced predation rate compared to those without associated magpie nests. This suggests that orioles prefer to nest near to magpies and that this preference has evolved due to the protection provided by neighbouring magpies. The nesting association results in the clumping of oriole nests around magpie nests, and therefore provides a possible explanation for the semi-colonial nature of Bullock's orioles.

Receptor noise as a determinant of colour thresholds.

Inferences about mechanisms at one particular stage of a visual pathway may be made from psychophysical thresholds only if the noise at the stage in question dominates that in the others. Spectral sensitivities, measured under bright conditions, for di-, tri-, and tetrachromatic eyes from a range of animals can be modelled by assuming that thresholds are set by colour opponency mechanisms whose performance is limited by photoreceptor noise, the achromatic signal being disregarded. Noise in the opponency channels themselves is therefore not statistically independent, and it is not possible to infer anything more about the channels from psychophysical thresholds. As well as giving insight into mechanisms of vision, the model predicts the performance of colour vision in animals where physiological and anatomical data on the eye are available, but there are no direct measurements of perceptual thresholds. The model, therefore, is widely applicable to comparative studies of eye design and visual ecology.

The Stability of the Oriole Hybrid Zone in Western Kansas

In the Great Plains of North America a number of species of birds that breed in woodland edge in the east are replaced by western counterparts (Rising 1983a). In many instances (Colaptes, Passerina, Pheucticus, Pipilo, and Icterus) the counterpart congeners apparently hybridize, often rather commonly, where their ranges are in contact. It is widely postulated that these eastern and western counterpart taxa differentiated in allopatry during the Pleistocene (Mengel 1970), and today are interbreeding following rather recent secondary contact (Rising 1983a). The consequences of this hybridization are not clear, but may be clarified by long-term studies (Selander 1965, Yang and Selander 1968, Rising 1983b, Moore and Buchanan 1985). The eastern Baltimore Oriole (Icterus galbula) and the western Bullock's Oriole (I. bullocki) are among the best studied of these east-west species pairs (Rising 1983a, 1983b). They hybridize in a zone of apparent secondary contact that runs from southwestern Alberta south through northeastern Montana and western North and South Dakota, Nebraska, Kansas, and Oklahoma. In 1965 and 1966 I collected orioles in riparian woodlands (principally cottonwoods [Populus]) from 14 sites along four river systems in western Kansas, the Republican, Smoky Hill, Arkansas, and Cimarron, that run essentially west to east through the oriole hybrid zone (Rising 1970). In 1976 and 1978, I recollected orioles from six of the sites that I had previously collected in the 1960s, along the Cimarron and Smoky Hill rivers, as well as a sample of Bullock's Orioles from along the Cimarron River near Kenton, Oklahoma, on the Oklahoma-New Mexico border (Rising 1983b) to serve as a western reference sample. Here I report on orioles that I collected in 1992 and 1993 from the same sites, shown in Figure 1, that I had collected in the 1970s; in 1992, I also collected a sample of Baltimore Orioles from central (Rice Co.) Kansas, to serve as an eastern reference sample. These three sets of collections, taken over a nearly 30-year span, allow me to directly assess the changes of oriole hybridization in western Kansas. METHODS

Scheduling Differences of Molt and Migration for Baltimore and Bullock's Orioles Persist in a Common Environment

Rohwer and Manning (1990) recently showed that Bullock's Orioles (Icterus galbula bullockii) migrate to the American Southwest prior to undergoing their fall molt. Thus, recently fledged young that are still in full juvenile plumage and adults that are in worn breeding plumage migrate at least as far as the southwestern U.S. and northern Mexico before undergoing their prebasic molt. Although Sealy (1979) reports that some second year male Baltimore Orioles (Icterus galbula galbula) may begin moving southward early in the fall molt, both the first and later prebasic molts of galbula take place on the breeding grounds. Rohwer and Manning (1990) suggest that bullockii migrates to the American Southwest before molting to escape the extremely dry late summer conditions of the coastal lowlands and intermountain west. In contrast, late summer monsoon rains characterize the American Southwest and should produce a food flush that birds could exploit to support their postjuvenile and postbreeding molts. Recently both Lazuli Buntings (Passerina amoena) and western populations of Painted Buntings (P. ciris) have also been shown to move to the American Southwest for their fall molts (Young 1991, Thompson 1991). Because Rohwer and Manning (1990) initiated their study of these orioles to test predictions distinguishing winter versus summer explanations of delayed plumage maturation (Rohwer and Butcher 1988), the specimens they examined largely excluded bullockii taken east of the Rocky Mountains. This left open the possibility that the differences in the fall molt/migration schedules of galbula and bullockii might be under environmental rather than genetic control. Interestingly, Corbin and Sibley (1977) report evidence of a reduced frequency of galbula x bullockii hybrids between the mid-1950s and the early 1970s along the Platte River of eastern Colorado and western Nebraska. Rohwer and Manning (1990) suggest that the dramatic differences in the molt and migration schedules of these orioles could constitute a potent source of selection against hybrids. For this to be true, however, the differences in the scheduling of their fall molts relative to the migration must be under genetic control. To eliminate environmental control we sought to examine all late summer specimens of bullockii and galbula from the Great Plains, a region where they should experience much more similar environmental conditions than they do in their larger allopatric ranges west of the Rocky Mountains and in eastern North America.

Differences in Timing and Number of Molts for Baltimore and Bullock's Orioles: Implications to Hybrid Fitness and Theories of Delayed Plumage Maturation

We compare the molt and migration schedules of Baltimore (Icterus g. galbula) and Bullock's (I. g. bullockii) orioles, describe how bullockii and Black-backed Orioles (I. g. abeillei) in juvenile plumage can be distinguished, and present a simple quantitative character that serves to distinguish the juvenile and basic plumages of bullockii. Galbula undergoes the first and later prebasic molts on the breeding grounds, while bullockii in both juvenile and worn breeding plumage almost certainly migrate to the American southwest prior to undertaking the fall molts. This early migration by bullockii has probably been favored as a mechanism for them to escape the dry late summer conditions that prevail in most of their breeding range and to exploit for molting the food flush caused by the late summer monsoon rains in the southwest. With but one exception, every bullockii specimen taken in late summer or fall south of the breeding range in Mexico was in fresh basic plumage. Thus, the fall migration of bullockii may be interrupted for the prebasic molts. Bullockii almost entirely lacks a prealternate molt in all sex and age classes. The prealternate molt in galbula is fairly extensive in first-year males but limited in females and in older males. First year galbula males initiate this molt in their throat in early winter, perhaps to acquire a badge that helps distinguish them from first-year females, which have light throats, and from those older females that have light throats. Some galbula males that are almost a year old also undergo part of the prealternate molt after their arrival on the breeding grounds. Implications of these observations for theories of subadult plumages are discussed. These differences between galbula and bullockii in the timing of the fall molts relative to the fall migration and in having or not having a prealternate molt may provide strong sources of selection against hybrids. One specimen illustrating some of the potentially deleterious recombinations of molt and migration schedules among hybrids is described in detail.

The Progress of Oriole Hybridization in Kansas

Abstract Specimens of Northern ("Baltimore" and "Bullock's") orioles collected at six sites in western Kansas in 1976 and 1978 are compared with specimens collected at the same sites in the mid-1960's. No changes in the location or size of the step-cline ("hybrid zone") between the two taxa are indicated by comparisons of the plumage features of the male specimens; the distribution of phenotypes of birds from sites where both Baltimore and Bullock's orioles occur is not bimodal, and, therefore, there is no indication of selection against intermediate birds. Female Bullock's-like orioles, however, are found farther east along the Cimarron River in southwestern Kansas than they were in the 1960's. The correlations between the amount of precipitation at a locality in western Kansas and the phenotype of oriole that occurs there are high (about 0.90). This suggests that precipitation per se is a factor that determines the distributional limits of these birds relative to each other. There are no recent changes, however, in the average climatic conditions in western Kansas. Perhaps the orioles present at a site in any given season are a reflection of the conditions there the previous season or two. The analyses of size variation among samples collected in the 1970's show an east-west cline that is more-or-less congruent with that found for plumage features; at any given site, the variability in size is positively correlated with the variability in plumage. Where a diversity of oriole phenotypes occurs, there is no tendency for females to associate with males of the "same type" (i.e. Bullock's with Bullock's or vice versa); this suggests that assortative mating does not occur.

GENIC CHANGES ASSOCIATED WITH THE ESTABLISHMENT OF SYMPATRY IN ORIOLES OF THE GENUS ICTERUS.

A study of the variation in plumage pattern and coloration in hybridizing orioles of the genus Icterus indicated that the two subspecies of the northern oriole, Icterus galbula galbula and I. g. bullockii, are sympatric in at least one locality in the Great Plains of North America (Corbin and Sibley, 1977). The genetic variation at 19 loci of the birds collected in that study is presented here. The observed allelic frequency differences are used to document further those changes that appear to be taking place in, and adjacent to, the of overlap and between the galbula and bullockii subspecies of the northern oriole. The observed sympatry between these two currently recognized subspecies might be a transient local condition resulting from a chance influx of the galbula phenotype into the range of distribution of the bullockii phenotype. However, we believe the evidence available supports the hypothesis that sympatry between the two subspecies has an underlying genetic basis, that sympatry developed in situ as a result of assortative mating and not because of rare dispersal events. As such,the condition may provide a better understanding of the genetic changes associated with the intermediate stages of the speciation process. We approach our hypothesis by considering: 1) how the allelic frequencies within and outside of the of contact might be altered following secondary contact between hybridizing, differentiated subspecies, and 2) how allelic frequencies might change within the of subsequent to selection against hybrids. Hybridization involving the orioles of the genus Icterus was first recognized by Sutton (1938) and subsequently studied in detail by Sibley and Short (1964), Sutton (1968), Rising (1968, 1969, 1970, 1973), Anderson (1971), Misra and Short (1974) and Corbin and Sibley (1977). In the mid1950s, the Baltimore oriole, Icterus galbula, and the Bullock's oriole, I. bullockii, were recognized as species. Morphologically, they could be distinguished on the basis of plumage pattern and coloration as well as on the basis of mensural characteristics such as wing length, tail length and body length. However, between them was extensive throughout the Great Plains of North America (Sibley and Short, 1964). Within the the average value of each of the various traits was intermediate between those of the parental phenotypes. (We use the term hybrid as defined by Short [1969:89], an area of where only hybrids occur, as distinguished from a zone of overlap and hybridization which is an area of secondary intergradation occupied by numerous hybrids and both parental forms.) There was evidence that introgression was bidirectional and that progeny were equally fit in comparison to the offspring of pure parental matings, although the latter was an inference based on the frequency of hybrids rather than on experimental breeding data. It appeared that premating isolating mechanisms were ab-

Rapid Evolution in Orioles of the Genus Icterus

first specimens to be recognized as hybrids were described by Sutton (1938), and the zone of hybridization has been studied by Sibley and Short (1964), Rising (1968, 1969, 1970, 1973), Anderson (1971), and Misra and Short (1974). The specimens collected during the 1950's by Sibley and Short (1964) indicated that the parental forms were behaving biologically as subspecies. As clarified by Short (1969), the parental types were allopatric and separated by a hybrid zone. At that time there was no zone of overlap and hybridization, within which both parental types existed in sympatry and in a combined frequency greater than 5% of the total population. That is, there was no apparent reinforcement of isolating mechanisms. In 1973 the A.O.U. Check-list Committee accepted the recommendation by Sibley and Short (1964) that the western forms (bullockii) be treated as subspecies of I. galbula. This decision was based primarily on birds collected along the Platte River, extending from Greeley, Colorado to Blair, Nebraska. However, Rising (1968, 1970) believed that the Bullock's Oriole and Baltimore Oriole should not be

A comparison of metabolism and evaporative water loss of baltimore and bullock orioles

1. 1. Both Baltimore and Bullock orioles use about 2·4 ml O 2/g per hr at thermoneutrality; this value is approximately 14 per cent lower than the 2·8 value predictable on the basis on mass alone. 2. 2. At 44·0°C, the highes T a used in this study, Baltimore orioles used significantly more O 2 than did Bullock orioles. 3. 3. The rate of evaporative water loss increased only gradually with an increase in T a at lower T a s, but increased markedly as T a approached T b ; at 44°C, approximately 100 per cent of the heat produced by metabolic activity was dissipated by evaporative water loss. 4. 4. Both forms showed an increase in T b at higher T a s; at moderate T a s, the T b of Bullock orioles is somewhat lower than that of Baltimore orioles, but at 44°C, Bullock orioles appeared to be higher; 25 per cent of the Baltimore orioles tested died at 44°C whereas none of the Bullock orioles died at this T a . 5. 5. The physiological responses of these two orioles correlate well with their ecological preferences. Where their ranges come into contact, Bullock orioles distributionally replace Baltimore orioles probably because they are physiologically better adapted to hot, dry regions.

Let's Make Bird Names Helpful

some changes a few years ago, they changed the name of the blue-headed vireo to the solitary vireo and, the American egret to the common egret. This kind of change is not inspired. All changes should be useful and significant. A clear goal is needed. Some names of bird species help in identification the chestnut-sided warbler; other names do not the Bewick's wren. I suggest this goal: change the unhelpful to helpful names. Many people have become birdwatchers only because someone encouraged them at the start to connect a name like Bell's vireo with a tiny, dull bird which doesn't look or act like a Bell or bell. A veritable thorn-hedge of such names creates a barrier which soon discourages many who might otherwise take an interest in bird-watching. We should do all we can to assist beginners. Breaking the name barrier would be a significant step. How many school children would learn the difference between a whitetailed deer and mule deer if these species were named Leconte's deer and Lichtenstein's deer? Since we use descriptive names for most mammals, why should we perpetuate nondescriptive names for so many birds? Beginners are not the only ones who could benefit by an improvement in the names of birds. In these days of increased travel, bird-watching can become an international sport if we give each species a name which will help to identify it on an international level. The white-winged dove is a perfect example, lending its name readily to Fig. 1. Black-crowned oriole. The old name, Bullock's oriole, does not help an inexperienced bird-watcher.

A Survey of the Birds of Death Valley

In 1893, A. K. Fisher, a member of the Death Valley Expedition under Dr. C. Hart Merriam, reported 69 species of birds in the below-sea-level region of Death Valley, California. Not until 1917, however, did Dr. Joseph Grinnell and Joseph Dixon continue the study of the avifauna of Death Valley. Grinnell used the sea level contour as the boundary of his study area and in 1923 published a list of 120 species. He wrote that an analysis of his list (1923:45) shows a constituency by seasonal categories which is much different from that usually obtaining in local lists: the proportion of breeding species to casual visitants, transients and winter visitants is exceedingly small. He pointed out that 25 of the 120 species were casual visitors or vagrants, 45 were regular transients, 31 were winter visitors, and 9 were summer visitors. Of these only one, the Bullock Oriole (Icterus bullockii) was known to breed in the below-sea-level area.