World Vultures Research Articles

Molecular phylogeny and biogeography of Honey-buzzards (genera Pernis and Henicopernis)

A partial sequence of the cytb gene (382 bp) was amplified and sequenced from 35 individuals (mainlymuseum specimens) of the genus Pernis representing all valid taxa (10) and two taxa (P. p. gurneyi, P. p. japonicus) with questionable validityas well as representatives of the Old World Perninae, namely Henicopernis and Aviceda, to assess their relationships to the genus Pernis. Furthermore, Gypaetus barbatus, Neophron percnopterus, and Buteo buteo were included as outgroup taxa. In the trees derived from the sequence data, Aviceda represents the sister group of the genus Pernis. The genus Henicopernis and the Old World vultures Gypaetus andNeophron appear rather distantlyrelated to Pernis. Within the genus Pernis, two of the described species (Pernis apivorus, Pernis ptilorhyncus) form monophyletic groups, whereas the relationships of the two clades representing three subspecies of Pernis celebensis are still uncertain. Although this studyis based on comparativelyshort DNA-sections, the trees deduced from these sequences can be considered as a first approach for inferring the phylogenetic relationships of the genus Pernis and related genera and for addressing questions concerning the evolutionary history, biogeography, and systematics of this group.

Coprophagy: an unusual source of essential carotenoids.

The rare Egyptian vulture (Neophron percnopterus) stands out among the Old World vultures (Family Accipitridae) because of its brightly ornamented head, which is coloured yellow by carotenoid pigments, and its practice of feeding on faeces. Here we show that Egyptian vultures obtain these pigments from the excrement of ungulates. To our knowledge, this is the first demonstration that faeces can be used as a source of carotenoids by a vertebrate.

Raptors of the world

This new field guide covers all of the world's kites, vultures, harriers, hawks, buzzards, eagles, and falcons. Based on essential sections of the widely acclaimed handbook Raptors of the World by the same authors, but with updated text, maps, and plates, it shows every species in a selection of different plumages, with concise facing texts and distribution maps. It provides an easy-to-use and portable reference to one of the world's largest, most popular, and most challenging avian groups. A unique identification guide to all the world's raptors, and includes 118 color plates that show 338 species in flight and perched. Facing text summarizes size, confusion species, habitat, and behavioral and plumage differences. Color distribution maps are included for every species. It is ideal for use in the field, anywhere in the world.

Cytogenetic analysis of California condor (Gymnogyps californianus) chromosomes: comparison with chicken (Gallus gallus) macrochromosomes

The California condor is the largest flying bird in North America and belongs to a group of New World vultures. Recovering from a near fatal population decline, and currently with only 197 extant individuals, the species remains listed as endangered. Very little genetic information exists for this species, although sexing methods employing chromosome analysis or W-chromosome specific amplification is routinely applied for the management of this monomorphic species. Keeping in mind that genetic conditions like chondrodystrophy have been identified, preliminary steps were undertaken in this study to understand the genome organization of the condor. This included an extensive cytogenetic analysis that provided (i) a chromosome number of 80 (with a likelihood of an extra pair of microchromosomes), and (ii) information on the centromeres, telomeres and nucleolus organizer regions. Further, a comparison between condor and chicken macrochromosomes was obtained by using individual chicken chromosome specific paints 1–9 and Z and W on condor metaphase spreads. Except for chromosomes 4 and Z, each of the chicken (GGA) macrochromosomes painted a single condor (GCA) macrochromosome. GGA4 paint detected complete homology with two condor chromosomes, viz., GCA4 and GCA9 providing additional proof that the latter are ancestral chromosomes in the birds. The chicken Z chromosome showed correspondence with both Z and W in the condor. The homology suggests that the condor sex chromosomes have not completely differentiated during evolution, which is unlike the majority of the non-ratites studied up till now. Overall, the study provides detailed cytogenetic and basic comparative information on condor chromosomes. These findings significantly advance the effort to study the chondrodystrophy that is responsible for over ten percent mortality in the condor.

Isolation and characterization of microsatellite loci in the bearded vulture (Gypaetus barbatus) and cross-amplification in three old world vulture species.

Keywords: Aegypius monachus; conservation genetics; cross-species amplification; Gypaetus barbatus; Gyps fulvus; Neophron percnopterus

Isolation and characterization of microsatellite loci in the bearded vulture (Gypaetus barbatus) and cross-amplification in three Old World vulture species

Isolation and characterization of microsatellite loci in the bearded vulture (Gypaetus barbatus) and cross-amplification in three Old World vulture species

Contributions of molecular studies to the phylogeny and systematics of African birds

Helbig, A.J. 2000. Contributions of molecular studies to the phylogeny and systematics of African birds. Ostrich 71 (1 & 2): 40. Recent advances in DNA technology allow us to study the phylogenetic relationships of birds from a completely new perspective and to base avian systematics on a more solid foundation. In the present paper, relationships of selected groups of birds (birds of prey, Sylviid warblers) will be analysed based on extensive nucleotide sequences of the mitochondrial cytochrome b gene. DNA was isolated from blood, amplified via polymerase chain reaction (PCR) and sequenced directly. Main findings include the following: (1) Old World vultures are polyphyletic with Neophron and Gypaetus being more primitive than the other species. (2) The primitive position of Pandion is confirmed. (3) Aquila rapax and, A. nipalensis are differentiated at species level. (4) Genetic differentiation is substantial in the kestrel complex (Falco tinnunculus, rupicoloides, naumanni), but only slight in the peregrine group (E p. peregrinus, brookei, minor, pelegrinoides). Sylviidae: (5) The genus Sylvia is paraphyletic relative to Parisoma, the latter is in itself not a monophylum and should be merged with Sylvia. (6) Acrocephalus griseldis is genetically a highly distinctive species; A. baeticatus is very similar to A. scirpaceus. Large and small-bodied species groups of reed warblers are each monophyletic. (7) Eastern and western forms of Hippolaispallida are strongly differentiated, probably demanding species status for each. (8) African “Seicercus” are members of the Phylloscopus radiation and probably derive from Asian rather than West Palearctic ancestors. (9) Cisticola and Prinia appear to be sister genera, Camaroptera is closer to these than to Palearctic genera. DNA studies are revolutionising avian systematics by providing easily comparable and highly reproducible information at all taxonomic levels: from within-species differentiation to higher level phylogeny. Mitochondrial DNA is also a suitable marker to study gene flow in hybrid zones and thus establish or refute biological species status of taxa in secondary contact.

Effects of sex-associated competitive asymmetries on foraging group structure and despotic distribution in Andean condors

Phenotype-limited interference models assume competitive asymmetries among conspecifics and unequal sharing of resources. Their main prediction is a correlation between dominance status and patch quality: dominant individuals should preferentially exploit better-quality habitats. We tested assumptions and predictions of the phenotype-limited interference model in Andean condors (Vultur gryphus), a New World vulture with strong sexual size dimorphism (males are 30–40% heavier than females). We recorded searching birds in habitats differing in quality: mountains and plains. We also observed scavenging behaviour at 20 sheep carcasses, and videotaped 5 of them. Intraspecific hierarchy at carcasses was based on size: males dominated females and, within each sex, older birds dominated younger ones. Adult males and juvenile females occupied extreme positions in the feeding hierarchy. Aggression was directed at those individuals belonging to lower hierarchical levels. In high-quality areas (mountains), more condors arrived at carcasses. Juvenile females were more often observed searching in low-quality areas (plains), far from breeding areas and main roost sites. GLM analyses of individual behaviour showed that the hierarchy did not influence time of arrival, but low-ranking individuals spent more time at carcasses, especially if the number of condors at arrival was high. Additionally, low-ranking condors spent less time feeding at carcasses when individuals of higher hierarchical levels were present. On the other hand, the number of condors present had a positive effect on feeding rates of dominant individuals, probably because of a reduction in individual vigilance. These results support most of the assumptions and predictions of the phenotype-limited distribution model, although a spatial truncated distribution between phenotypes was not observed. Asymmetric feeding pay-off, unequal parental roles and sexual selection constraints could favour sexual divergence in body size in Andean condors.

Raptors as Indicators of Environmental Change in the Scrub Habitat of Baja California Sur, Mexico

“Indicator” species of natural habitat quality are potentially useful tools for managers of biodiversity (Rohlf 1991). Predators are often considered indicators because they are at the top of food webs and need wide home-range areas to function. Predators play an important role in ecosystems because they can determine the community structure patterns of their prey (Menge et al. 1994). In addition, predators, including facultative scavengers, have been used as “umbrella” species in world conservation strategies because their protection may facilitate the conservation of great portions of unaltered habitats (Simberloff 1987). Raptors, here defined to include New World vultures, Falconiformes, and Strigiformes, have been considered good indicators of habitat quality because of their sensitivity to human disturbance and environmental contamination (Newton 1979; Taylor 1984). Population declines of some raptor species indicate dysfunctional ecosystems because population dynamics of top-order predators often reflect the nature of the ecosystems they inhabit (Newton 1979; Greene 1988; Olendorff et al. 1989; Burnham et al. 1990; Terborgh 1992). Thus, it has been recommended that raptors should be included in the management and conservation plans of any region, especially for threatened habitats (Olendorff et al. 1989; Burnham et al. 1990). The use of raptors as indicator species has been particularly advocated for tropical forests (Thiollay 1989, 1996). Their role as indicators of habitat naturalness in Neotropical areas, however, remains controversial. Raptors may benefit from some human activities (Vannini 1989; Bird et al. 1996). Some raptors may be opportunistic when habitat changes occur because new feeding sources and nesting structures become available (Donazar et al. 1993 a ). We examined how local breeding and wintering raptor populations are affected by human activities in the desert of Baja California, until recently one of the most undisturbed areas in the world. Habitat changes have occurred along the peninsula over the last 10 years, especially in the southern part of Baja California, mostly because of increasing human activity (Masey & Palacios 1994). Because management plans for the region may include extensive land-use changes throughout Baja California (OEA-SEDESOL-INE 1993), data on the potential effects of these changes on the status and distribution of vertebrates should be considered. Because most raptors are considered sensitive species, we expected that populations of most species of raptors would be negatively affected by anthropogenic changes in the environment.

A Randomized Nearest-Neighbor Approach for Assessment of Character Displacement: the Vulture Guild as a Model

Character displacement has been analysed in the past but not with an approach that considers nearest-neighbor distances between members of a guild. Vultures provide a model system in which to test a new analytical approach presented here to assess character displacement. Vultures are represented by two geographically isolated and taxonomically distinct groups: the Old World accipitrids and New World vultures. These two groups provide an excellent case of convergent evolution in which functional similarities can be compared among obligate carrion-feeding birds. The vulture guild was analysed from several geographic regions where species occur in a high diversity: East Africa, South Africa, the Indian subcontinent, Amazonia, and the pleistocene deposits from Rancho La Brea, California. A three-dimensional morphospace was constructed derived from features of the skull, beak, and mandible to assess feeding capabilities. Species packing and their distribution within the morphospace were compared using a nearest-neighbor approach through Monte Carlo simulations. Vultures seem to exhibit a similar array of ecomorphological types wherever they occur in a high diversity, even though there are phylogenetic differences among some regions. Phylogenetic effects appear to have little influence on the distribution of functional types in each region and evidence for character displacement was found only at Rancho La Brea where both Old and New World vultures were present.

Phylogeny of the Avian Family Ciconiidae (Storks) Based on CytochromebSequences and DNA–DNA Hybridization Distances

This study is a phylogenetic analysis of the avian family Ciconiidae, the storks, based on two molecular data sets: 1065 base pairs of sequence from the mitochondrial cytochromebgene and a complete matrix of single-copy nuclear DNA–DNA hybridization distances. Sixteen of the nineteen stork species were included in the cytochromebdata matrix, and fifteen in the DNA–DNA hybridization matrix. Both matrices included outgroups from the families Cathartidae (New World vultures) and Threskiornithidae (ibises, spoonbills). Optimal trees based on the two data sets were congruent in those nodes with strong bootstrap support. In the best-fit tree based on DNA–DNA hybridization distances, nodes defining relationships among very recently diverged species had low bootstrap support, while nodes defining more distant relationships had strong bootstrap support. In the optimal trees based on the sequence data, nodes defining relationships among recently diverged species had strong bootstrap support, while nodes defining basal relationships in the family had weak support and were incongruent among analyses. A combinable-component consensus of the best-fit DNA–DNA hybridization tree and a consensus tree based on different analyses of the cytochromebsequences provide the best estimate of relationships among stork species based on the two data sets.

A mtDNA Phylogeny of Sea Eagles (genus Haliaeetus) Based on Nucleotide Sequences of the Cytochrome b-gene

The mitochondrial cytochrome b gene of seven species of sea eagles H. albicilla, H. leucocephalus, H. leucoryphus, H. leucogaster, H. sanfordi, H. pelagicus and H. vocifer was amplified by PCR and sequenced (1026 bp). Phylogeny reconstructions by the Maximum Parsimony and Neighbour-Joining methods produced similar trees in which sea eagles represent a monophyletic group. In addition, the clade H. albicilla/H. leucocephalus groups with the clade H. pelagicus/H. leucoryphus in a monophyletic boreal group while H. vocifer clusters with the H. leucogaster/H. sanfordi clade in a monophyletic tropical clade. The nearest relatives of sea eagles are the kites (genus Milvus ) and buzzards (genus Buteo ), whereas ‘booted’ eagles (genus Aquila ) and vultures (genera Gyps and Aegypius ) have diverged earlier from the accipitrid branch. Honey bussards (genus Pernis ) and vultures of the genera Gypaetus and Neophron represent basal taxa of the accipitrid lineage. Falcons, New World vultures and the secretary bird ( Sagittarius ) appear in separate clades outside the Accipitridae.

A mtDNA phylogeny of sea eagles (genus Haliaeetus) based on nucleotide sequences of the cytochrome b-gene

The mitochondrial cytochrome b gene of seven species of sea eagles H. albicilla, H. leucocephalus, H. leucoryphus, H. leucogaster, H. sanfordi, H. pelagicus and H. vocifer was amplified by PCR and sequenced (1026 bp). Phylogeny reconstructions by the Maximum Parsimony and Neighbour-Joining methods produced similar trees in which sea eagles represent a monophyletic group. In addition, the clade H. albicilla/H. leucocephalus groups with the clade H. pelagicus/H. leucoryphus in a monophyletic boreal group while H. vocifer clusters with the H. leucogaster/H. sanfordi clade in a monophyletic tropical clade. The nearest relatives of sea eagles are the kites (genus Milvus) and buzzards (genus Buteo), whereas ‘booted’ eagles (genus Aquila) and vultures (genera Gyps and Aegypius) have diverged earlier from the accipitrid branch. Honey bussards (genus Pernis) and vultures of the genera Gypaetus and Neophron represent basal taxa of the accipitrid lineage. Falcons, New World vultures and the secretary bird ( Sagittarius) appear in separate clades outside the Accipitridae.

First isolation of tandemly repeated DNA sequences in New World vultures and phylogenetic implications.

A highly repeated DNA sequence composed of closely related subunits that ranged from 171 to 176 base pairs has been cloned and characterized in the king vulture (Sarcoramphus papa). Related sequences were also isolated in the black vulture (Coragyps atratus). This new family of avian repetitive DNA elements is here termed the "HaeIII family." Genomic DNAs from a number of avian species were probed with one of the king vulture restriction fragments. In the cathartids, the hybridization patterns showed no individual or sexual variations. A strong HaeIII ladder was present in the two aforementioned species as well as in the Andean condor (Vultur gryphus), but in the black vulture the bands of the ladder alternated in intensity. Weaker hybridization signals were obtained in two ciconids, the jabiru stork (Jabiru mycteria) and the white stork (Ciconia ciconia). The HaeIII repeat was not detected in accipitrid birds of prey, a Polyborinae falconid, pelecanids, and psittacids.

Evolutionary history of New and Old World vultures inferred from nucleotide sequences of the mitochondrial cytochrome b gene.

The phylogeny of 11 species of Old World vultures (Aves: Accipitriformes, Aegypiinae), three species of New World vultures (Cathartidae) and theri nearest relatives within and outside the order Accipitriformes was investigated based on 1026 nucleotides of the mitochondrial cytochrome b gene. The data support the contention that New World vultures are not birds of prey, but phylogenetic information was insufficient to identify whether they are closer to storks (Ciconiidae) or to Accipitriformes. Four species of Gyps are all closely related and probably speciated within the Pleistocene. Molecular data do not support the split of 'white-backed' vultures from Gyps in a separate genus Pseudogyps. The monotypic genera of large, heavy-billed vultures, Aegypius, Torgos, Trigonoceps and Sarcogyps, are of monophyletic origin. We propose to merge Torgos with Aegypius, but retain Trigonoceps and Sarcogyps as separate genera, Sarcogyps being clearly the most primitive of the four. All four, together with Gyps and Necrosyrtes, form a monophyletic subfamily or 'core group', to which the subfamily Aegypiinae should be restricted. This group shares a more recent common ancestor with several non-vulture genera of Accipitrids, among them Buteo, Aquila, Haliaeetus and Circaetus, than it does with the two aberrent vultures Gypaetus barbatus and Neophron percnopterus. The last two are much more primitive; they seem to be each other's sister species and are closer to Pernis than to other Accipitrids. We propose separating Gypaetus and Neophron in the subfamily Gypaetinae. If the cytochrome b gene tree accurately reflects vulture phylogeny, Old World vultures are polyphyletic with the Aegypius-Gyps clade having evolved convergently to the more ancient Gypaetus and Neophron vultures. Polyphyly of Old World vultures, although in conflict with the DNA-DNA hybridization phylogeny of Sibley & Ahlquist (1990), is well supported by molecular, karyotypic, morphological and other phenotypic evidence (behaviour, voice) indicating fundamental differences between the two evolutionary lines.

DNA sequence support for a close phylogenetic relationship between some storks and New World vultures

DNA sequence support for a close phylogenetic relationship between some storks and New World vultures

Habitat Associations of Migrant and Resident Vultures in Central Venezuela

We investigated spatial and temporal differences in the habitat associations of five New World vulture taxa (family Vulturidae auct. Cathartidae) in the Llanos of central Venezuela. Overall numbers of vultures were higher over open or semi-open savanna habitats than closed canopy riverine gallery forest. Black Vultures Coragyps atratus brasiliensis and Lesser Yellow-headed Vultures Cathartes burrovianus foraged principally in open habitats at all times. Although King Vultures Sarcoramphus papa were counted mainly over gallery forest they also sometimes foraged outside the forest area. During the wet season, resident Turkey Vultures Cathartes aura ruficollis foraged in all habitats but highest densities occurred over gallery forest, east of the main highway. This indicated that, to some extent, vulture species were ecologically segregated by habitat. During the dry season, a larger, dominant, migratory race of Turkey Vulture, C. a. meridionalis, coexisted with the resident subspecies. Migrants foraged at highest densities over open and semi-open habitats, but they also occurred in low numbers over gallery forest. When sympatric with these migrants, resident Turkey Vultures foraged almost exclusively in closed gallery and semi-deciduous tropical forest to the east of the highway, and, in contrast to the wet season, avoided open habitats. At the end of the dry season (March to April), migrant Turkey Vultures departed for North America to breed, resulting in a dramatic reduction in densities of Cathartes vultures. Despite the absence of migrants, densities of Cathartes vultures remained higher in open and semi-open savanna habitats than the gallery forest area. Support for a possible niche shift came from the proportion of carcasses visited in different habitats by resident Turkey Vultures, habitat sightings of wing-tagged birds and radiotracking studies.

Diversity in Body Size and Feeding Morphology within Past and Present Vulture Assemblages

Vultures comprise two geographically isolated and taxonomically distinct groups, Old World accipitrids and New World vulturids, and provide a classic case of convergent evolution. In both regions, several species of vultures often feed together in large numbers on carcasses. Behavioral studies of East African and Amazonian vultures have documented parallels in apparent ecological separation within this guild of specialized scavengers. Here morphological differences in skull, beak, and manibular dimensions are compared among sympatric vultures in East Africa, South Africa, the Indian subcontinent, Amazonia, and the Pleistocene Rancho La Brea deposits in California. A discriminant function analysis based on morphological indices separates three basic feeding types: rippers, gulpers, and scrappers. Vultures of the three feeding types are present in both Pleistocene and Recent assemblages and show a similar distribution of body sizes into three size classes, suggesting that competition has favored similar pathways of ecological separation. This is true even when phylogenetic differences among some of the assemblages are partially accounted for. Comparisons between the fossil and extant New World vultures indicate that more specialized species were prone to extinction and that there has been a reduction in body size since the Pleistocene.

DNA sequence support for a close phylogenetic relationship between some storks and New World vultures.

Nucleotide sequences from the mitochondrial cytochrome b gene were used to address a controversial suggestion that New World vultures are related more closely to storks than to Old World vultures. Phylogenetic analyses of 1-kb sequences from 18 relevant avian species indicate that the similarities in morphology and behavior between New World and Old World vultures probably manifest convergent adaptations associated with carrion-feeding, rather than propinquity of descent. Direct sequence evidence for a close phylogenetic alliance between at least some New World vultures and storks lends support to conclusions reached previously from DNA.DNA hybridization methods and detailed morphology-based appraisals, and it illustrates how mistaken assumptions of homology for organismal adaptations can compromise biological classifications. However, there was a lack of significant resolution for most other branches in the cytochrome b phylogenetic reconstructions. This irresolution is most likely attributable to a close temporal clustering of nodes, rather than to ceiling effects (mutational saturation) producing an inappropriate window of resolution for the cytochrome b sequences.

Avian Egg Morphometrics - Allometric Models of Egg Volume, Clutch Volume and Shape

This paper describes three comprehensive new models of the allometric relationships between egg volume, clutch volume and shape, and body weight. Mean egg dimensions, clutch sizes and adult body weights were obtained for 326 species, mainly of four bird types: raptors (including owls), shorebirds, frogmouths (including nightjars), and storks (including the New World vultures). These are groups in which there is a wide range of body sizes and of sexual dimorphism in body size (in direction and degree). Female body weight alone accounted for 92% of the variation in egg volume. Sexual dimorphism in body size, phylogenetic relationship, and clutch size were significant contributors to the model of egg volume; their addition increased the explained variance to over 98%. The model was curvilinear (quadratic) in form, rather than linear as assumed in previous models. Larger species laid smaller eggs than expected under a simple power function. For the fitted model, within bird types, generic groupings had parallel curvilinear slopes but differing intercepts. Between bird types, the slopes differed. Clutch volume was scaled to body weight; all the bird types had a common slope, which was curvilinear. Body weight and dimorphism accounted for 89.5% of the variation in clutch volume. For all bird types, eggs became proportionally longer in shape as body weight increased, according to a simple power law. The relevance of these relationships to hypotheses on the evolution and adaptive significance of sexual dimorphism and to the trade-off between egg size and clutch size is discussed briefly.