Structure and colour-production of the blue barbs of Agapornis roseicollis and Cotinga maynana

Summary The spongy structure in medullary cells responsible for the colour of blue barbs in rump feathers of Agapornis roseicollis and back feathers of Cotinga maynana is studied with the scanning and the transmission electron microscope. The Agapornis structure is an irregular three-dimensional network of connected keratin rods which in many places form rings with outer diameters 0.25–0.3 . The air-filled space likewise consists of an irregular network of connected channels. The Cotinga structure consists of spherical cavities fairly evenly distributed in a keratin matrix.Earlier spectrophotometric measurements on the Agapornis structure have shown that the colour production has to be ascribed to the interference of light, not to Rayleigh (Tyndall) scattering as previously held. The optical path lengths corresponding to the outer diameter of the Agapornis rings and to the Cotinga cavities including their horny walls both are c. 0.4 . It is suggested that the colours are produced by the interference of light reflected from the front and rear surfaces of the rings, respectively the spherical cavities.I wish to thank Miss Annelise Nørgaard Jensen, Institute of Historical Geology and Palaeontology, University of Copenhagen, for operating the scanning electron microscope for me.     

Thermal biology of African lovebirds and Australian grass parakeets

We compared aspects of the thermal biology of two groups of small parrots, of similar body mass, each derived from a range of habitat types, varying in aridity, but indigenous to either southern Africa or Australia. By accounting for phylogenetic differences, we were able to question whether arid zone species have lower metabolic rates and greater thermal tolerances than mesic species in relation to the “pre-adapted” and “post-arrival adaptation” hypotheses. Four species of African lovebird (Agapornis) and four species of Australian grass parakeet (one Neopsephotus and three Neophema species) were investigated. The Rosy-faced Lovebird (Agapornis roseicollis), Bourke's Parakeet (Neopsephotus bourkii) and the Scarlet-chested Parakeet (Neophema splendida) were categorised as arid zone species, Fischer's Lovebird (Agapornis fischeri), the Black-masked Lovebird (Agapornis personatus) and the Elegant Parakeet (Neophema elegans) as semi-arid zone species, and the Black-cheeked Lovebird (Agapornis nigrigenis) and the Turquoise Parakeet (Neophema pulchella) as mesic zone species. Conventional and phylogenetically independent statistical methods yielded no significant differences in the basal metabolic rates of birds from different habitats or between the species assemblages from Africa and Australia.     

4. THE SOUTH AFRICAN CLIFF SWALLOW

Short, L.L. &; Horne, J. F. M. 1980, Vocal and other behaviour of the Green Barbet in Kenya. Ostrich 51:219–229.

Brief field studies of the Green Barbet Stactolaema olivacea in coastal Kenya, with emphasis on vocalizations, document its social behaviour, including communal roosting of four birds in a cavity. Green Barbets are aggressive, interacting strongly with a number of species. Erecting of the crown feathers, cocking of the tail, and woodpeckerlike swinging movements characterize displays. Wing Flutters and audible Bill Wiping are visual-auditory displays. Vocalizations include the Grating Call, Kek Call, Chuk Call and Chowp Call. These are agonistic and agonistic-reproductive in function. The Chowp Call comprises the song, used in simultaneous singing and duetting.     

Losing the last feather: feather loss as an antipredator adaptation in birds

Birds often lose feathers during predation attempts, and thisability has evolved as a means of escape. Because predatorsare more likely to grab feathers on the rump and the back thanon the ventral side of an escaping bird, we predicted that theformer feathers would have evolved to be relatively looselyattached as an antipredator strategy in species that frequentlydie from predation. We estimated the force required to removefeathers from the rump, back, and breast by pulling featherswith a spring balance from a range of European bird speciesin an attempt to investigate ecological factors associated withease of feather loss during predation attempts. The force requiredto loosen a feather from the rump was less than that requiredto loosen a feather from back, which in turn was less than thatrequired to loosen a feather from the breast. The relative forceneeded to loosen rump feathers compared with feathers from theback and the breast was smaller for prey species preferred bythe most common predator of small passerine birds, the sparrowhawkAccipiter nisus. Likewise, the relative force was also smallerin species with a high frequency of complete tail loss amongfree-living birds, which we used as an index of the frequencyof failed predation attempts. The relative force required toremove feathers from the rump was smaller in species with ahigh frequency of fear screams, another measure of the relativeimportance of predation as a cause of death. Feather loss requiredparticularly little force among solitarily breeding bird speciesthat suffer the highest degree of predation. Antipredator defensein terms of force required to remove feathers from the rumpwas larger in species with a strong antiparasite defense interms of T-cell–mediated immune response. These findingsare consistent with the hypothesis that different defenses areantagonistic and that they are traded off against each other.     

Skuas (Stercorarius spp.) moult body feathers during both the breeding and inter‐breeding periods: implications for stable isotope investigations in seabirds

Seabirds are mostly thought to moult during the inter‐breeding period and the isotopic values of their feathers are often therefore assumed to relate to their assimilated diet during such periods. We observed Brown Skuas Stercorarius antarcticus lonnbergi and South Polar Skuas Stercorarius maccormicki moulting on a breeding site at King George Island, Antarctica. This raises concerns about the reliability of using stable isotopes in feathers to infer feeding localities of birds during the inter‐breeding period. We analysed the δ¹³C and δ¹⁵N values of growing and fully grown body feathers collected from the same individuals. For both species, δ¹³C values of growing feathers indicated feeding areas in the Antarctic zone (breeding grounds), whereas most fully grown feathers (100% for South Polar Skuas and 93.3% for Brown Skuas) could be assigned to northern latitudes (non‐breeding grounds). However, a few fully grown body feathers of Brown Skuas (6.7% of the feathers, belonging to two birds) showed isotopic values that indicated moult in the Antarctic zone. As the growth period of those feathers was unknown, they could not be used with confidence to depict the foraging behaviour of the birds during the non‐breeding period. Although precautions must be taken when inferring dietary information from feathers in seabirds where the moulting pattern is unknown, this study shows that if the development stage of a feather (growing/fully grown) is identified, then dietary information from both breeding and non‐breeding seasons can be obtained on the same individual birds.     

Plumage colour variations in the Agapornis genus: a review

The genus Agapornis consists of nine small African parrot species that are globally well known as pets, but are also found in their native habitat. Illegal trapping, poaching and habitat destruction are the main threats these birds face in the wild. In aviculture, Agapornis breeding is highly popular all across the globe. Birds are mainly selected based on their plumage colour variations but very little molecular research has been conducted on this topic. There are 30 known colour variations amongst the nine species and most of these are inherited as Mendelian traits. However, to date none of the genes or polymorphisms linked to these variations have been identified or verified. Due to unethical breeding practices, the need for the development of molecular tests such as identification verification tests or species identity tests is growing. Future research is paramount to ensure the conservation of wild populations as well as aiding breeders in improving breeding strategies.     

Biological monitoring of exposure to ambient lead and cadmium using avian feathers: A study from Northern India

Biological monitoring of exposure to ambient environmental lead and cadmium was performed using feathers of 26 species of birds native to Western Uttar Pradesh in Northern India. The rationale of this study was to address three questions. First, is there any avian species that can be treated as a suitable bioindicator of lead or cadmium present in the environment? Second, do the birds selectively accumulate lead and cadmium in their feathers and exhibit interspecies variation? Third, is there any threat to endangered species of this region from metal pollution? Average concentration of lead in the feathers of selected birds ranged from 3.40 µg/g in parrot to 301.6 µg/g in golden pheasant, whereas cadmium concentration was higher ranging from 40.20 µg/g in red crow to 450 µg/g in blue macaw. A comparison of results made through ANOVA revealed a significant difference in the concentration of lead (df = 25; F = 3965.54) and cadmium (df = 25; F = 8537.27) in their feathers. We hypothesize that feathers of synanthropic birds may be treated as suitable noninvasive tool to monitor the ambient environmental contamination by lead and cadmium. Their accumulation in endangered birds may lead to population decline causing serious ecological disturbances in the region.     

Feather isotope analysis discriminates age-classes of Western, Least, and Semipalmated sandpipers when plumage methods are unreliable

ABSTRACT Avian age‐class discrimination is typically based on the completeness of the first prebasic molt. In several calidrid sandpiper species, juvenal flight feathers grown on Arctic breeding grounds are retained through the first three migrations. Thereafter, flight feathers are grown annually at temperate migratory stopover sites during the fall or on the subtropical wintering grounds. Standard methods for distinguishing age classes of sandpipers rely on a combination of traits, including body plumage, coloration of protected inner median covert edges, and extent of flight feather wear. We tested the ability of stable hydrogen isotope ratios in flight feathers (δD_f) to distinguish young birds in their first winter through second fall from older adults in three calidrid sandpiper species, Western (Calidris mauri), Least (C. minutilla), and Semipalmated (C. pusilla) sandpipers. We compared the apparent reliability of the isotope approach to that of plumage‐based aging. The large expected differences in δD_f values of flight feathers grown at Arctic versus non‐Arctic latitudes enabled use of this technique to discriminate between age‐classes. We determined δD_f values of known Arctic‐grown feathers from juveniles that grew their flight feathers on the breeding grounds. Flight feather δD_f values of southward‐migrating adults showed bimodal distributions for all three species. Negative values overlapped with species‐specific juvenile values, identifying putative second fall birds with high‐latitude grown juvenal feathers retained from the previous year. The more positive values identified older adults who grew their feathers at mid‐ and low latitudes. Importantly, δD_f analysis successfully identified first‐winter and second‐fall birds not detected by plumage‐based aging. Flight feather wear alone was a poor basis for age classification because scores overlapped extensively between putative second fall birds and older adults. Flight feather hydrogen isotope analysis enables more definitive assignment of age classes when standard plumage methods are unreliable.     

Microbial Diversity of Wild Bird Feathers Revealed throughCulture-Based and Culture-Independent Techniques

Despite recent interest in the interactions between birds and environmental microbes, the identities of the bacteria that inhabit the feathers of wild birds remain largely unknown. We used culture-based and culture-independent surveys of the feathers of eastern bluebirds (Sialis sialis) to examine bacterial flora. When used to analyze feathers taken from the same birds, the two survey techniques produced different results. Species of the poorly defined genus Pseudomonas were most common in the molecular survey, whereas species of the genus Bacillus were predominant in the culture-based survey. This difference may have been caused by biases in both the culture and polymerase chain reaction techniques that we used. The pooled results from both techniques indicate that the overall community is diverse and composed largely of members of the Firmicutes and β- and γ- subdivisions of the Proteobacteria. For the most part, bacterial sequences isolated from birds were closely related to sequences of soil-borne and water-borne bacteria in the GenBank database, suggesting that birds may have acquired many of these bacteria from the environment. However, the metabolic properties and optimal growth requirements of several isolates suggest that some of the bacteria may have a specialized association with feathers.     

Using IRAP markers for analysis of genetic variability in populations of resource and rare species of plants

Species-specific LTR retrotransposons were first cloned in five rare relic species of drug plants located in the Perm’ region. Sequences of LTR retrotransposons were used for PCR analysis based on amplification of repeated sequences from LTR or other sites of retrotransposons (IRAP). Genetic diversity was studied in six populations of rare relic species of plants Adonis vernalis L. by means of the IRAP method; 125 polymorphic IRAP-markers were analyzed. Parameters for DNA polymorphism and genetic diversity of A. vernalis populations were determined.     

Sex-dependent frequency and consequences of natural handicaps in American Kestrels

Natural selection theory suggests that there should be fitness consequences for animals that possess morphological abnormalities such as missing or deformed appendages and other structures. As these characters are expected to be detrimental, morphological abnormalities could be considered “handicaps”. However, little information exists about the nature, prevalence or consequences of naturally occurring handicaps in birds, even though experimental handicapping has been used in some behavioural studies. Here, we document and describe the frequency of natural handicaps in American Kestrels Falco sparverius, and investigate their influence on condition and survival. We considered three different categories of handicap that should negatively impact falcons: missing remiges and rectrices, broken remiges and rectrices, and foot handicaps. Broken feathers, followed by missing feathers, were the most common handicaps detected in kestrels and their prevalence increased throughout the breeding season. Foot handicaps were relatively rare and showed no seasonal trends. There was no effect of any handicap type on body condition or return rates of male kestrels. In contrast, females with either foot handicaps or broken feathers were in significantly poorer condition than control females, and females with broken feathers were less likely than control females to return to the study area in years following initial capture. Given that female kestrels with broken feathers have more fault bars than those without broken feathers, and fault bar formation is related to stresses in a bird's past, we suggest that female kestrels that had broken feathers were of poorer quality than those without broken feathers or those with missing feathers. Females with broken feathers may therefore have been in poorer condition initially than other birds, or if broken feathers are indicative of poor quality, then females with broken feathers may have been less able to cope with the negative impacts of feather loss on flight performance compared to birds with missing feathers.     

Stress,Behaviour and Immunity in Wild‐Caught Wintering Great Tits (Parus major)

The associations between behaviour, stress and immune responses are most likely a result of common integration through the neuroendocrine system. Here, we describe associations between behaviour and immunity in great tits, Parus major. Wild‐caught birds were brought into captivity, and their immune function was assessed on the basis of antibody production to a novel Brucella abortus antigen and of heterophil/lymphocyte (H/L) ratio, which is also a haematological marker of stress. Two behavioural traits were evaluated: tolerance to captive conditions on the basis of damage inflicted to tail feathers and propensity to produce alarm calls at release. The birds that had highest H/L ratios at capture inflicted the maximum extent of tail damage during the week spent in captivity and produced lowest antibody titres against a novel antigen, which indicates a strong covariation between the tolerance of captivity, perceived stress and immune responsiveness. Propensity to produce alarm calls was lower in birds who tolerated captivity better. Structural equation modelling proposed the existence of an underlying latent variable affecting all the measured traits and causing the correlations between traits. Our study indicates that connections between behaviour and immunity can be easily detected in wild animals.     

Hearing and communication in birds: the cocktail-party-effect in intraspecific communication of Agapornis roseicollis (aves, psittacidae).

Lovebirds ($\text{Agapornis roseicollis}$) were able to detect recorded acoustic signals of their mates from background noise (vocalizations of birds of the same species); signal-to-noise ratio 13 dB.Signal detection and intelligibility at different levels is so far known to be based on two components: The preferential motivation of the signal recipient as a psycho-physical factor, and - in the case of voice recognition in background noise - the possession of two ears as the physical factor. Since this complex phenomenon, termed the cocktail-party-effect, has first been investigated in the acoustic behaviour of humans (1,2), ethologists have supposed that this effect also exists in the animal acoustic behaviour of Vertebrates (3,4,5) and probably Invertebrates (pers. comm.).     

Two new parrot species (Psittaciformes) from the early Pliocene of Langebaanweg,South Africa,and their palaeoecological implications

Two new parrot species (Psittaciformes) are described from the early Pliocene Varswater Formation at Langebaanweg, South Africa, an area where no parrots currently are found. A coracoid, humeri, ulnae, carpometacarpi, tibiotarsi and tarsometatarsi of at least four individuals are assigned to a new species of lovebird Agapornis. Additional tarsometatarsi of at least five individuals including a nestling are referred to a new genus and species of Psittacinae, a taxon endemic to Africa comprising the extant genera Poicephalus and Psittacus. Both species form the as yet earliest geological record of parrots in Africa and document the early diversification of the taxa Agapornis and Psittacinae. Evidence for parrots in general, and a putative graminivorous species of lovebird in particular, indicates that woodlands as well as grasslands were present at Langebaanweg during the early Pliocene, which is consistent with current hypotheses on the palaeoenvironment at and around this site.     

Reproductive Isolation in the Wood Cricket Gryllus vernalis (Orthoptera: Gryllidae)

Two species of closely related wood crickets, Gryllus vernalis (Orthoptera: Gryllidae) and G. fultoni, occur together in the eastern USA and have a similar calling‐song structure, consisting of three‐pulse chirps. Previous studies revealed that male calling song and female selectivity were divergent between sympatric and far allopatric populations of G. fultoni, consistent with the pattern expected of reproductive character displacement. We studied the reproductive isolation of G. vernalis in relation to G. fultoni by investigating the geographic variation in calling songs of G. vernalis and by examining close‐range mating behaviors. Neither field nor laboratory studies revealed differences in any of the calling‐song characters between sympatric and allopatric populations, but this could reflect the limited sampling within the relatively small region of allopatry for G. vernalis. Although close‐range mating trials revealed that females of both species discriminated against heterospecific mating partners, the strength of discrimination was especially strong in females of sympatric G. vernalis populations. Our studies of long‐range and close‐range mating behaviors suggest that selection pressures for reproductive isolation are exerted primarily on close‐range mating behaviors in G. vernalis but on long‐range mating behaviors in G. fultoni.     

High error rates for avian molecular sex identification primer sets applied to molted feathers

ABSTRACT Molted feathers are becoming increasingly important as a source of DNA for identifying the sex of individuals, and accurate methods for molecular sex identification are needed. Three molecular sex identification primer sets have been developed for use in nearly all nonratite birds, but performance of these primer sets has not been evaluated for molted feathers. For two species of birds, the Ring‐necked Pheasant (Phasianus colchicus) and the Scarlet Macaw (Ara macao), we evaluated success and error rates among primer sets using DNA from molted feathers and assessed the percentage of times an incorrect sex would be assigned when analyses are completed in duplicate. Amplification success rates differed among the primer sets for both species, ranging from 67.5% to 89.2% (P= 0.0002 and 0.009), and error rates were high, ranging from 1.9% to 24.2%. Success rates and error rates were not consistent between species and among primer sets. To improve the accuracy of molecular sex identification tests when using molted feathers, we suggest determining acceptable confidence levels in the accuracy of sex assignment, conducting pilot tests to evaluate the performance of different primer sets, and using high‐resolution electrophoresis systems to increase detection of errors.     

CHAIRMAN'S REPOST, 1954–55

Brown, C. R. 1986. Feather growth, mass loss and duration of moult in Macaroni and Rockhopper Penguins. Ostrich 57:180-184.

The development of new feathers, loss of body mass and the duration of moult were investigated in Macaroni Penguins Eudyptes chrysolophus and Rockhopper Penguins E. chrysocome at Marion Island, southern Indian Ocean. New feathers began developing under the skin before the birds returned ashore to moult, and only began protruding through the skin about five days later when they were already over half their final length. Feather synthesis was complete by 21 days after the birds returned ashore. Loss of body mass was similar to previous observations for the species, but previous reports on the duration of moult do not take into account that moult begins while the birds are still at sea.     

THE BIOLOGY OF THE WAVED ALBATROSS DIOMEDEA IRRORATA OF HOOD ISLAND, GALAPAGOS

As a nesting species, the Waved Albatross Diomedea irrorata is restricted to Hood Island in the Galapagos archipelago where 12,000 pairs bred in 1971. Outside the islands the species occurs over the northern parts of the Humboldt Current. Two colonies were studied in detail (1970–1971). At the start of a season, males returned first to the colonies and defended a small territory. Copulation occurred without any elaborate ceremony and the female spent little time on land before laying. There was no fixed nest-site, even within a season, and birds moved their eggs considerable distances. This resulted in heavy egg losses. Younger birds bred later than older birds and laid longer but narrower eggs. The average incubation spell varied from four to five days at the extremes of the incubation period to 19 days in the middle. The average incubation and fledging periods were 60 and 167 days respectively. Pairs which lost an egg sometimes adopted the abandoned egg of another bird and successfully reared the chick. Most pairs nested in both seasons. Nesting success was extremely variable, both between years and between colonies. Between 1961 and 1971 at Punta Suarez, virtually no young were reared in four seasons. Even in 1970–71, where nesting success was good, some groups of birds deserted their eggs en masse whereas in neighbouring areas up to 80% of the pairs reared young. The main foods of the young were squid and fish. Birds did not moult wing and tail feathers at the breeding colonies, and about 50% retained some primaries for more than one season, suggesting that successful pairs had difficulty in fitting in a complete moult between breeding attempts. Old feathers were normally found among the inner primaries and at the next moult were preferentially replaced, though adjacent newer feathers were sometimes retained for another season. Some birds bred in their fourth years, but most not until a year or two older. Immatures were present at the colonies late in the breeding cycle, the youngest returning latest and remaining until the last young fledged. Survival of adults and young averaged at least 95% and 93% per annum over many years. Adults and young ringed in 1961 survived equally well. The significance of the timing of the return of immatures and of the large-scale desertion of eggs, apparently not due to food shortage or disturbance, is discussed.     

MOULT IN FIVE SPECIES OF CORVIDAE IN BRITAIN

This paper presents objective methods for measuring moult and uses them to describe the pattern and rate of the complete moult as a component of the annual cycle in Corvus corone, C. frugilegus, C. monedula, Pica pica and Garrulus glandarius in Britain. The basis of the methods used to measure the rate of moult was the dry weight of the whole plumage and its component tracts and feathers. Within whole tracts of flight feathers showing diversity of size, the longer feathers grew in length a little faster than the others by accumulating feather material very much faster. Thus, for the flight feathers at least length by itself was a poor indicator of size, but, if first related to weight, could be used to predict weight. Hence, to enable realistic comparisons to be made between different flight feathers and tracts of flight feathers on a given individual bird or on individuals of different species, a ‘units’ system was created which would take account of such variations in size. This information provided a standard against which the growth of new flight feathers in a specimen collected in the field could be measured. The progress of moult in each tract was indicated by the sum of the units. In addition, for both the flight feathers and all other tracts, the duration of moult was measured from the start and finish in each tract as indicated by the proportion of birds having either growing or entirely fully-grown feathers in each tract. In the annual cycle body weight and abdominal fat weight were at a maximum in mid-winter and at a minimum in mid-summer in Corvus; variations in these items were apparently absent in G. glandarius. In Corvus probably only post-second-year birds breed, but in P. pica some second-year individuals do so as well; also, increase in testes size in second-year males was greatest in P. pica. The patterns of the relative seasonal timing of the start and finish of moult in each tract were most similar in the three Corvus species, in which moult in the whole plumage began in the primary tract and finished in tracts on the body; P. pica differed principally in the extended growth of the secondary tract; G. glandarius differed in that moult began in the dorsal tract. By summing the data from individual tracts, a measure of the rate of growth in the whole plumage was obtained: all five species moulted at essentially the same time of year. In the primary, secondary, tertiary and rectricial tracts the seasonal accumulation of dry weight of feather material in each tract followed a sigmoid pattern; in the alula tract dry weight increased most rapidly at the beginning. These patterns were correlated with the numbers of feathers growing at different stages in each tract. The primary tract accumulated dry matter at the highest relative rate, while the rectricial, secondary, tertiary and alula tracts did so at successively lower rates. The maximum relative rate of increase in dry weight in any given tract of flight feathers was fairly similar in all five species, but was possibly related inversely to body weight. Maximum absolute rates of increase in dry tract weight were also calculated. During the springtime period when non-moulting and moulting birds were present simultaneously in the population, no difference could be detected between these groups in any species in body and fat weights; in individuals obtained together with evidence of reproductive activity, few had begun primary moult, but in post-second-year C. frugilegus with branchers, males began before females; in C. corone and C. frugilegus testes weight was lower in moulting than in non-moulting birds. In conclusion, some aspects of moult for further research are suggested.