Hornbills are omnivorous and the breeding male delivers all food required by the nest-confined female and chicks. The contributions of different food types, in terms of breeding nutrition, have not previously been documented. In Khao Yai National Park, Thailand, we sampled the identity and number of food items delivered daily to the nest, during each week of the nesting cycle, by two small and two large sympatric species of hornbills. We then recorded the mass and estimated the nutrient content of each food type from analyses of protein, fat, carbohydrate, calcium, and energy. The overall pattern of nutrient delivery during the nesting cycle was the same for each of the four hornbill species, and was related to sequential demands for egg, feather, and chick development. The two larger species delivered mainly carbohydrates (Great Buceros bicornis 50%, Wreathed Aceros undulatus 57%) and less fat and protein. The smallest, Oriental Pied Hornbill Anthracoceros albirostris, also delivered mostly carbohydrate (45%), but the small White-throated Brown Hornbill Anorrhinus austeni delivered equivalent proportions of protein (32%), fat (30%), and carbohydrate (37%). Comparison of the incubation and nestling phases showed that more protein was delivered during the nestling phase for all species, except for Great Hornbill where the compression of egg production, incubation, and molt had to be completed by midway through the nestling phase and so high levels of fat and protein were delivered during incubation. We confirmed that fruits are an important source of all nutrients, especially fat, for all four hornbill species, but suggest that delivery of animal protein may be linked, in some way, to breeding success. Oriental Pied Hornbill broods, that received protein at about 1.05% of brood mass per day, had the highest breeding success (96%) whereas Wreathed Hornbills received only 0.57% protein and had only 67% success, while the other two species delivered intermediate amounts of protein and had intermediate breeding success.
Information on breeding success of birds of the Indian subcontinent is almost negligible. The present study, carried out during the breeding seasons of 1997-1999 inclusive at Hardwar in northern India (29°55′N; 78°8′E), compared the breeding success of Spotted Munia Lonchura punctulata in urbanized and more natural forested habitats. A significant difference was found in total breeding success between the two habitats, being 48.7% in urban areas and only 31.6% in forest. Although differences in eggs hatched (70.3% vs 60.3%) and nestlings reared (57.7% vs 51.9%) were less, significantly more fledglings survived in urban areas (89.0%) than in forested habitat (70.9%). This indicates that the greater breeding success of Spotted Munia in urbanized habitats is due primarily to higher rates of post fledgling survival there. A number of factors may affect reproductive success differently between habitats. In forest, nests were built in isolated thorny trees (e.g. Acasia nilotica) outside of forest canopy cover. In urban areas, however, the trees or shrubs selected for nesting were mostly of introduced species (e.g. Thuja orientalis, Polyanthea longifolia), all densely foliaged and rendering predation difficult. Although the typical habitat of Hardwar town is not natural, the Spotted Munia has evidently adapted quickly and successfully in its landscape. Such shifts in behaviour are not instantaneous and newly acquired behaviour takes time to spread. It would be interesting to determine whether these behavioural shifts in Spotted Munia are based on culturally transmitted learning or on genetic change.
The bills of the spoonbills differ from the bills of most birds by being wider near the downward curved tip than in the middle, and having the mandibles dorso-ventrally extremely flattened. The mandibles have rounded lateral borders and lack cutting edges. The inward directed sides have a dense cover of thin parallel ridges on the distal parts and rows of teeth-like tubercles in the proximate parts. Their skeletons have numerous small pits in the distal parts especially along the edges and the insides. These pits are similar to the spaces for sensory corpuscles for touch in the bills of Scolopacidae (sandpipers, snipes) and are presumed to have the same function in spoonbills. The bill seems adapted for tactile feeding with lateral movements (sweeping) and for pecking, but not for probing into sediments. The wide gape with gular pouch allows the swallowing of rather large food items. The muscular layer of the gizzard is weakly developed and the gizzard is more a digestive pocket than a chewing organ such as occurs for grinding hard shells and grains in molluscivorous and granivorous birds. The long legs are laterally flattened, perhaps for minimising resistance and not-disturbing prey when walking in water during feeding; the partly webbed feet with long toes allow walking over soft mud bottoms.
The present paper describes the microscopic structure and distribution of various elements in the eggshell from the Black-tailed Gull Larus crassirostris. Scanning and transmission electron microscopy (SEM and TEM) in combination with light microscopy demonstrated four major zones in the eggshell: the shell membrane (SM), the mammillary zone (MZ), the palisade region (PR), and the cuticle layer (CL). The SM was composed of a further three layers: i.e. the limiting membrane and the inner and outer SMs consisting of thin fibers. The MZ was a layer lined with conical knobs, the mammillare, each of which had a core portion characterized by a dense matrix with a few vesicles and aggregated fine fibrils. The PR showed a spongy feature depicted as numerous vesicles embedded in a calcified matrix. The CL appeared as a simple structure different from that seen in the eggshells from other birds, such as grebes, cormorants and domestic fowl. X-ray compositional microanalysis (XCM) revealed differences in the distribution patterns of certain elements (Ca, Mg, and P) in the radial face of the eggshell. The concentration of Ca was markedly high throughout the true shell (MZ and PR), whereas that of Mg was locally high in the MZ. The concentration of P was slightly higher in the surface crystal layer of the PR than elsewhere.
The conservation status and evolutionary distinctiveness of the isolated, small, and endemic population of Amak Island Song Sparrows (Melospiza melodia amaka) have been equivocal. Coupled with a reassessment of phenotypic evidence for this taxon, we used mitochondrial cytochrome b sequences and eight microsatellite loci to evaluate the relationship of the Amak population to nearby Song Sparrow populations. Phenotypically, M. m. amaka is not a valid taxon, and we found that Amak Song Sparrows possess no unique haplotypes and have allele frequencies and heterozygosity values similar to those in other populations. Congruence between genetic and morphological evidence suggesting no diagnosable differences leads us to propose that this population is not an evolutionarily significant unit (ESU), not a valid subspecies, not a distinct population segment (DPS), nor a diagnosable conservation unit, but rather a sink colonized by regional source populations.
Erythrina suberosa blooms during the dry-season. The flowers are large, papilionaceous, and partly self-compatible. The floral characteristics provide an example of ornithophilous pollination; all the flowers are pollinated exclusively by passerine birds. The fruit set rate was only 10%, but this was compensated for by a higher seed set rate. The flowers normally produce seven ovules, with those in the number two and five positions appearing to be the most preferred for seed development.
Disturbances that shift a community away from its potential natural state may also degrade the quality of that community for some species. Having an index to measure changes in habitat quality resulting from such disturbances would be useful in assessing the impact of human activities on native fauna. We propose that average egg mass per clutch and offspring size for a population in a particular habitat may be a useful index of habitat quality, and perhaps degradation, for that population relative to the status of populations occupying other similar habitats in that region. We studied American Robins (Turdus migratorius) breeding along streams in three canyons on the western side of the Toiyabe Mountains of central Nevada, USA. The level of habitat degradation associated with cattle grazing and other human activities was determined a priori based on soil and understory vegetation characteristics. The density of adult birds and their body condition did not differ among canyons with differing habitat quality, nor did clutch size or brood size at day 8. However, nests containing larger eggs and chicks were associated with canyons assessed as having a higher quality, or lower level of degradation.