Juvenile Birds Research Articles

Post-fledging dispersal of Maltese Yelkouan Shearwaters Puffinus yelkouan

Satellite tags were attached to ten juvenile Yelkouan Shearwaters from a breeding colony in Malta to study post-fledging dispersal patterns. Of the eight birds with usable data, all moved eastwards almost immediately after leaving their nest sites. The majority of birds migrated to the islands off the western coast of Greece with one then moving on into the Aegean Sea and another to the South Adriatic Basin. While most birds migrated to Greek waters, two followed a different route, undertaking a wide circuit of the eastern Mediterranean and eventually ending up along the northern coast of Africa. The bird that transmitted for the longest period (68 days) was last recorded in the northern Aegean where it had spent the majority of the time. This study has shown that Maltese Yelkouan Shearwaters range over a large area during the first few weeks of fledging and follow widely varying routes. It has also demonstrated the importance of Greek waters for juvenile Yelkouans from Maltese colonies. The difficulty in tracking juvenile Yelkouan Shearwaters using this method has been highlighted by this study, and it is suggested that further methods are explored to track juvenile birds during the months after fledging.

Use of a barbed tool by an adult and a juvenile woodpecker finch (Cactospiza pallida)

Here we describe the modification and use of a new tool type in the woodpecker finch (Cactospiza pallida). This species is known to habitually use twigs or cactus spines to extract arthropods out of tree holes. We observed an adult and a juvenile bird using several barbed twigs from introduced blackberry bushes (Rubus niveus) which the adult bird had first modified by removing leaves and side twigs. The barbs of blackberry tools provide a novel functional feature not present in tools made from native plants and de-leafing of twigs never has been observed before. Both birds were observed using several of these tools to extract prey from under the bark of the native scalesia tree (Scalesia penduculta). They oriented the twigs such that the barbs pointed towards themselves; this rendered the barbs functional as they could be used to drag prey out of a crevice. The juvenile bird first watched the adult using the tool and then used the tool that the adult bird had left under the bark at the same location and in the same way as the adult. Our observation highlights the fact that opportunities for the transmission of social information do occur in the wild and indicates that woodpecker finches are flexible in their choice of tool material and tool modification.

Hepatic Concentrations of Inorganic Contaminants and Their Relationships with Nutrient Reserves in Autumn-Migrant Common Loons at Lake Erie

Common loons (Gavia immer) are piscivorous, high-trophic level feeders that bioaccumulate inorganic contaminants at concentrations that can negatively impact their health and reproduction. Concentrations of inorganic contaminants, especially mercury (Hg), in blood, organs, and muscle have been quantified in common loons on breeding grounds, but these data are limited for migrating loons. We investigated sex- and age-related hepatic concentrations of inorganic contaminants in common loons (n=53) that died from botulism and were salvaged at a Great Lakes staging area (i.e., Long Point, Lake Erie) during November 2005. We also investigated if hepatic concentrations of inorganic contaminants influenced lipid, protein, and mineral in our sample of migrant common loons. Last, we determined if there was correlation between Hg and selenium (Se). Consistent with data from breeding grounds, mean concentrations of Hg in liver were approximately 2.5 times greater in adult ([Formula: see text]=14.64±16.69μgg(-1)) compared with juvenile birds ([Formula: see text]=3.99±2.27μgg(-1)). Elements detected in liver at potentially harmful levels were Hg and Se, of which lipid reserves varied negatively with Hg concentrations but positively with Se concentrations. In addition, Hg and Se were correlated (r=0.65) at greater then a demethylation threshold (total Hg≥8.5μgg(-1) dw) but not lower than that. Concentrations of inorganic contaminants did not influence protein and mineral levels in our sample of common loons. Our results suggest that Hg accumulation negatively affects lipid levels in migrant common loons. Results are also consistent with a nontoxic Hg-Se protein complex protecting loons migrating through areas that are relatively Se rich. Although the acquisition of Se during the nonbreeding season may decrease the toxicity of Hg, future research should consider the synergistic Hg-Se effect on reproduction in common loons that migrate through Se-rich locales, such as the Great Lakes.

PRESENCE AND SEASONAL PREVALENCE OF PLASMODIUM SPP. IN A RARE ENDEMIC NEW ZEALAND PASSERINE (TIEKE OR SADDLEBACK, PHILESTURNUS CARUNCULATUS)

The conservation and management of Saddlebacks (Philesturnus carunculatus) and other New Zealand birds, currently relies on the translocation of individuals to predator-free sites. Avian malaria has been identified as one of the diseases to be tested for prior to translocations in New Zealand, with the aim of translocating disease-free individuals. We describe avian malaria lineages and their seasonal prevalence in 2007-2008 in Saddlebacks from Mokoia Island, a source of birds for translocations, and investigate their pathogenicity. Three lineages of avian malaria were found at low prevalence (≤10.6%) and parasitemia (all but one infection were below 1/10,000 erythrocytes), typical of chronic infections. Two lineages clustered with previously identified lineages of Plasmodium relictum and one with a lineage of Plasmodium (Huffia) elongatum. Prevalence of malaria infection was higher in the spring with no significant difference in prevalence between juvenile and adult birds. We found no effect of stress on infections or any indication of pathogenicity.

Monitoring Passerine Reproduction by Constant Effort Ringing: Evaluation of the Efficiency of Trend Detection

The Dutch Constant Effort Site (CES) programme has been operating since 1994 and is especially designed for the analysis of demographic parameters. Currently, it works with 40 active mist-netting sites and has a database with more than 250,000 records at its disposal. Here, we ask whether the effort invested in the programme is appropriate to detect temporal trends of productivity of passerine bird populations across The Netherlands. We specifically ask if less effort would produce the same results or if the number of CESs should be augmented. To evaluate these questions we used a resampling approach in which we decreased sample size in steps of five and iterated resampling 1000 times for each step, thus simulating CES programmes in which fewer sites were operated. For the twenty most abundant species and for each sample size, linear regressions of the productivity index (a logistic generalized linear model of the proportion of captured juvenile birds) on year were compared with the regression obtained using the complete records. The proportion of samples that yielded significant positive or negative slopes was determined, as well. For the majority of species without significant temporal trends (18), the proportions of significant slopes at smaller sample sizes were lower than 20%, indicating a moderate risk of committing Type I errors (detecting a negative or positive trend although productivity did not change over time). For the Garden Warbler Sylvia borin, which showed a significant positive productivity trend, the probability of committing Type II errors (not detecting existing trends) increased rapidly with decreasing sample size. We conclude that the Dutch CES programme works with a sufficient number of sites to detect reliable temporal trends for most of the more abundant passerine species. However, increasing the number of sites would allow for a more secure determination of productivity trends for those species that currently show ambiguous results (Reed Warbler Acrocephalus scirpaceus, Willow Warbler Phylloscopus trochilus, Willow Tit Parus montanus).

Migratory Birds: Ecology and Conservation. A report on the BOU’s Annual Conference held at the University of Leicester, 5–7 April 2011

In April 2011, the British Ornithologist’s Union’s annual conference took place at the University of Leicester. The theme of this year’s conference was the ecology and conservation of migratory birds, and talks ranged from those focussed on either breeding, migration or wintering ecology, to those linking two or more of these and trying to build a more complete picture of the complex problems faced by long distance migrants. Talks also covered recent technological advances, which are increasingly allowing us intriguing new insights, particularly into the seasonal movements and wintering areas of some of the most declining species. Finally, talks examined the policy challenges associated with protecting migratory species and how best to tackle flyway-scale conservation of migratory birds.

Aerobic capacity in wild satin bowerbirds: repeatability and effects of age, sex and condition

Individual variation in aerobic capacity has been extensively studied, especially with respect to condition, maturity or pathogen infection, and to gain insights into mechanistic foundations of performance. However, its relationship to mate competition is less well understood, particularly for animals in natural habitats. We examined aerobic capacity [maximum rate of O2 consumption (VO2,max) in forced exercise] in wild satin bowerbirds, an Australian passerine with a non-resource based mating system and strong intermale sexual competition. We tested for repeatability of mass and VO2,max, differences among age and sex classes, and effects of several condition indices. In adult males, we examined interactions between aerobic performance and bower ownership (required for male mating success). There was significant repeatability of mass and VO2,max within and between years, but between-year repeatability was lower than within-year repeatability. VO2,max varied with an overall scaling to mass(0.791), but most variance in VO2,max was not explained by mass. Indicators of condition (tarsus and wing length asymmetry, the ratio of tarsus length to mass) were not correlated to VO2,max. Ectoparasite counts were weakly correlated to VO2,max across all age-sex classes but not within any class. Adult males, the cohort with the most intense levels of mating competition, had higher VO2,max than juvenile birds or adult females. However, there was no difference between the VO2,max of bower-owning males and that of males not known to hold bowers. Thus one major factor determining male reproductive success was not correlated to aerobic performance.

Reference Intervals for Intraocular Pressure Measured by Rebound Tonometry in Ten Raptor Species and Factors Affecting the Intraocular Pressure

Intraocular pressure (IOP) was measured with the TonoVet rebound tonometer in 10 raptor species, and possible factors affecting IOP were investigated. A complete ophthalmic examination was performed, and IOP was assessed in 2 positions, upright and dorsal recumbency, in 237 birds belonging to the families Accipitridae, Falconidae, Strigidae, and Tytonidae. Mean IOP values of healthy eyes were calculated for each species, and differences between families, species, age, sex, left and right eye, as well as the 2 body positions were evaluated. Physiologic fluctuations of IOP were assessed by measuring IOP serially for 5 days at the same time of day in 15 birds of 3 species. Results showed IOP values varied by family and species, with the following mean IOP values (mm Hg +/- SD) determined: white-tailed sea eagle (Haliaeetus albicilla), 26.9 +/- 5.8; red kite (Milvus milvus), 13.0 +/- 5.5; northern goshawk (Accipiter gentilis), 18.3 +/- 3.8; Eurasian sparrowhawk (Accipiter nisus), 15.5 +/- 2.5; common buzzard (Buteo buteo), 26.9 +/- 7.0; common kestrel (Falco tinnunculus), 9.8 +/- 2.5; peregrine falcon, (Falco peregrinus), 12.7 +/- 5.8; tawny owl (Strix aluco), 9.4 +/- 4.1; long-eared owl (Asio otus), 7.8 +/- 3.2; and barn owl (Tyto alba), 10.8 +/- 3.8. No significant differences were found between sexes or between left and right eyes. In goshawks, common buzzards, and common kestrels, mean IOP was significantly lower in juvenile birds than it was in adult birds. Mean IOP differed significantly by body position in tawny owls (P = .01) and common buzzards (P = .04). By measuring IOP over several days, mean physiologic variations of +/- 2 mm Hg were detected. Differences in IOP between species and age groups should be considered when interpreting tonometric results. Physiologic fluctuations of IOP may occur and should not be misinterpreted. These results show that rebound tonometry is a useful diagnostic tool in measuring IOP in birds of prey because it provides rapid results and is well tolerated by birds.

Neural coding of syntactic structure in learned vocalizations in songbirds

Birdsong is an important sexually selected trait, and its acoustic features are socially transmitted in the process of song learning. The preference of some female songbirds for song complexity as measured by repertoire size has driven the evolution of many song traits and song-learning programs in males. If juvenile birds adopt the attractiveness of model birds by copying their repertoires, tutor choice in the early song-learning period should be crucial for future reproductive success. Thus, we hypothesized that the song quality of tutors influences the tutor choice of chicks in the Bengalese finch, Lonchura striata var. domestica. Each subject chick was reared by a foster pair in an individual breeding cage. At around the fledging period, we introduced another unrelated adult male (subtutor) into each cage to simulate the natural social environment in which chicks have opportunities to hear the songs of nonfather males after fledging. Subject chicks learned from both tutors when the total note repertoire size of the two models was small; they tended to learn from the subtutor when the father had a smaller note repertoire size. The acquired note repertoire size was not affected by whether subjects learned songs from the foster father or not. Song learning from the subtutor contributed to a larger note repertoire. Observed patterns in tutor choice, in particular song learning from a subtutor, could be an adaptive strategy that helps chicks compensate for exposure to smaller repertoire size in models.

The broad range of contractile behaviour of the avian pectoralis: functional and evolutionary implications

Wing-assisted incline running (WAIR) in birds combines the use of the wings and hindlimbs to ascend otherwise insurmountable obstacles. It is a means of escape in precocial birds before they are able to fly, and it is used by a variety of juvenile and adult birds as an alternative to flight for exploiting complex three-dimensional environments at the interface of the ground and air. WAIR and controlled flapping descent (CFD) are the bases of the ontogenetic-transitional wing hypothesis, wherein WAIR and CFD are proposed to be extant biomechanical analogs for incremental adaptive stages in the evolutionary origin of flight. A primary assumption of the hypothesis is that work and power requirements from the primary downstroke muscle, the pectoralis, incrementally increase from shallow- to steep-angled terrestrial locomotion, and between terrestrial and aerial locomotion. To test this assumption, we measured in vivo force, electromyographic (EMG) activity and length change in the pectoralis of pigeons (Columba livia) as the birds engaged in shallow and steep WAIR (65 and 85 deg, respectively) and in three modes of slow flight immediately following take-off: ascending at 80 deg, level and descending at -60 deg. Mean EMG amplitude, muscle stress, strain, work and power were minimal during shallow WAIR and increased stepwise from steep WAIR to descending flight and level flight to reach the highest levels during ascending flight. Relative to resting length of the pectoralis, fractional lengthening (maximum muscle strain) was similar among behaviors, but fractional shortening (minimum muscle strain) was absent during WAIR such that the pectoralis did not shorten to less than the resting length. These data dramatically extend the known range of in vivo contractile behavior for the pectoralis in birds. We conclude that WAIR remains a useful extant model for the evolutionary transition from terrestrial to aerial locomotion in birds because work and power requirements from the pectoralis increase incrementally during WAIR and from WAIR to flight.

Migration patterns and morphometrics of Common Sandpipers Actitis hypoleucos at Ottenby, southeastern Sweden

Current knowledge of the migration of the Common Sandpiper Actitis hypoleucos is still limited. The species has been ringed at Ottenby Bird Observatory, southeast Sweden, since 1947, allowing for analyses of long-term and seasonal trends. We analysed trapping data for 1,942 adults and 3,290 juveniles with respect to patterns in phenology, morphometrics, and fuel load. We used fuel loads to estimate potential flight ranges. The number of adult birds trapped increased significantly over the years, whereas juveniles declined. Median passage date was 27 July and 7 August for adult and juvenile birds respectively, and juveniles showed a significant advancement in median passage date. Mean fuel loads were 28.8% and 27.8% of lean body mass (LBM) for adult and juvenile birds respectively, while maximum fuel load was as high as 98.7% in juveniles and 105.4% in adults. Fuel load increased significantly with date in juveniles but declined in adults. Advancement in passage of juvenile birds over the year is possibly due to climate change. Also, the average adult and juvenile are theoretically capable of a direct flight to central France; a major recovery area. Fuel load patterns suggest that in autumn, the two age classes use different migration strategies.

Bird Mercury Concentrations Change Rapidly as Chicks Age: Toxicological Risk is Highest at Hatching and Fledging

Toxicological risk of methylmercury exposure to juvenile birds is complex due to the highly transient nature of mercury concentrations as chicks age. We examined total mercury and methylmercury concentrations in blood, liver, kidney, muscle, and feathers of 111 Forster's tern (Sterna forsteri), 69 black-necked stilt (Himantopus mexicanus), and 43 American avocet (Recurvirostra americana) chicks as they aged from hatching through postfledging at wetlands that had either low or high mercury contamination in San Francisco Bay, California. For each waterbird species, internal tissue, and wetland, total mercury and methylmercury concentrations changed rapidly as chicks aged and exhibited a quadratic, U-shaped pattern from hatching through postfledging. Mercury concentrations were highest immediately after hatching, due to maternally deposited mercury in eggs, then rapidly declined as chicks aged and diluted their mercury body burden through growth in size and mercury depuration into growing feathers. Mercury concentrations then increased during fledging when mass gain and feather growth slowed, while chicks continued to acquire dietary mercury. In contrast to mercury in internal tissues, mercury concentrations in chick feathers were highly variable and declined linearly with age. For 58 recaptured Forster's tern chicks, the proportional change in blood mercury concentration was negatively related to the proportional change in body mass, but not to the amount of feathers or wing length. Thus, mercury concentrations declined more in chicks that gained more mass between sampling events. The U-shaped pattern of mercury concentrations from hatching to fledging indicates that juvenile birds may be at highest risk to methylmercury toxicity shortly after hatching when maternally deposited mercury concentrations are still high and again after fledging when opportunities for mass dilution and mercury excretion into feathers are limited.

Social Interactions of Juvenile Brown Boobies at Sea as Observed with Animal-Borne Video Cameras

While social interactions play a crucial role on the development of young individuals, those of highly mobile juvenile birds in inaccessible environments are difficult to observe. In this study, we deployed miniaturised video recorders on juvenile brown boobies Sula leucogaster, which had been hand-fed beginning a few days after hatching, to examine how social interactions between tagged juveniles and other birds affected their flight and foraging behaviour. Juveniles flew longer with congeners, especially with adult birds, than solitarily. In addition, approximately 40% of foraging occurred close to aggregations of congeners and other species. Young seabirds voluntarily followed other birds, which may directly enhance their foraging success and improve foraging and flying skills during their developmental stage, or both.

Occurrence of Chlamydiaceae in non-symptomatic free-living raptors in Spain

Few studies have investigated the role of raptors as natural reservoirs of Chlamydiaceae spp. and the preferred anatomical sites where these bacteria can be detected in non-symptomatic wild birds. We investigated the occurrence of Chlamydiaceae in 54 non-symptomatic adult free-living birds belonging to 14 species sampled upon reception in a raptor rehabilitation centre in Spain, and ten juvenile birds from five species born and reared in the centre for subsequent release into the wild. Swabs from conjunctivae, choanae and cloacae were taken to detect Chlamydiaceae DNA by a family-specific polymerase chain reaction (PCR) and a nested genus- and species-specific PCR. Chlamydiaceae DNA was detected in adult raptors belonging to 12 species (85.7%), mainly in conjunctival (40.6%) and, to a lesser extent, choanal (17.2%) swabs, but never in cloacal samples. Neither the genus nor the species of Chlamydiaceae could be confirmed by the nested PCR assay. Our results suggest that most of the raptor species investigated, especially the Common Kestrel (Falco tinnunculus) and Eurasian Griffon Vulture (Gyps fulvus), can be natural reservoirs of Chlamydiaceae spp. in the wild. Failure to identify the organisms at genus and species level might have been due to the poor quality and low concentration of DNA in the samples or to the presence of hitherto unclassified Chlamydiaceae species.

Regulation of learned vocal behavior by an auditory motor cortical nucleus in juvenile zebra finches

In the process of song learning, songbirds such as the zebra finch shape their initial soft and poorly formed vocalizations (subsong) first into variable plastic songs with a discernable recurring motif and then into highly stereotyped adult songs. A premotor brain area critically involved in plastic and adult song production is the cortical nucleus HVC. One of HVC's primary afferents, the nucleus interface of the nidopallium (NIf), provides a significant source of auditory input to HVC. However, the premotor involvement of NIf has not been extensively studied yet. Here we report that brief and reversible pharmacological inactivation of NIf in juvenile birds leads to transient degradation of plastic song toward subsong, as revealed by spectral and temporal song features. No such song degradation is seen following NIf inactivation in adults. However, in both juveniles and adults NIf inactivation leads to a transient decrease in song stereotypy. Our findings reveal a contribution of NIf to song production in juveniles that agrees with its known role in adults in mediating thalamic drive to downstream vocal motor areas during sleep.

Song repertoire size in male song sparrows correlates with detour reaching, but not with other cognitive measures

Song learning is a cognitive task in which juvenile birds acquire, store and use information about adult song to shape their own song production. Comparative studies show that across bird species, performance on different cognitive tasks is usually positively correlated. If the same holds true within species, then the complexity of a male’s learned song ought to be correlated with other cognitive abilities. To test this hypothesis, we measured correlations between song repertoire size and cognitive performance in wild song sparrows, Melospiza melodia . Females prefer males with larger song repertoires in this species, and song repertoire size correlates with various fitness measures. We recorded males’ song repertoires in the field and tested these males in captivity on motor, colour association and reversal learning tasks, as well as on a detour-reaching task that measures inhibitory control. We found that individuals’ performance on the colour association task correlated positively with their performance on the reversal task, but performance did not correlate across the other learning tasks. Males with larger song repertoires were faster to solve the detour-reaching task, but performed worse on the reversal task than males with smaller song repertoires. Although our results suggest that song repertoire size does correlate with one measure of cognitive performance, more detailed song analyses and further cognitive tests are required to answer the questions raised by our findings.

Autumn migration of robins (Erithacus rubecula) in Hungary

The purpose of this study was to describe the autumn migration dynamics of juvenile (n = 3075) and adult (n = 596) robin Erithacus rubecula in Hungary. Capturing and ringing of birds took place at five bird ringing stations of Actio Hungarica between 13 August and 27 October, 2004. The number of captured juvenile and adult individuals rated to one net was the lowest in the reeds of Izsak and the highest in the woody areas of Szalonna, where adults were present at a higher proportion. The migration dynamics of the robin showed that the end of September and the beginning of October was the peak time for passing through Hungary. Based on the estimated time of the 10% of daily capture, it can be stated that juvenile birds started their migration as early as the end of August or at the beginning of September while the migration of the adults started later. The migration started earliest in Szalonna and latest in Izsak. The comparison of daily catch dynamics (based on the estimated time of 10% and 50% of daily captures) of juveniles and adults between study sites showed that similarity of daily capture was higher in the case of juveniles. The five study sites had different qualities from the point of view of the robins’ habitat preference. Our results showed that the reed-bed of Izsak had only peripheral importance while the other forest and bushy study areas played a key role in resting and feeding during the migration of the robin.

Juvenile Songbirds Compensate for Displacement to Oceanic Islands during Autumn Migration

To what degree juvenile migrant birds are able to correct for orientation errors or wind drift is still largely unknown. We studied the orientation of passerines on the Faroe Islands far off the normal migration routes of European migrants. The ability to compensate for displacement was tested in naturally occurring vagrants presumably displaced by wind and in birds experimentally displaced 1100 km from Denmark to the Faroes. The orientation was studied in orientation cages as well as in the free-flying birds after release by tracking departures using small radio transmitters. Both the naturally displaced and the experimentally displaced birds oriented in more easterly directions on the Faroes than was observed in Denmark prior to displacement. This pattern was even more pronounced in departure directions, perhaps because of wind influence. The clear directional compensation found even in experimentally displaced birds indicates that first-year birds can also possess the ability to correct for displacement in some circumstances, possibly involving either some primitive form of true navigation, or ‘sign posts’, but the cues used for this are highly speculative. We also found some indications of differences between species in the reaction to displacement. Such differences might be involved in the diversity of results reported in displacement studies so far.

Volatile and Semivolatile Compounds in Gray Catbird Uropygial Secretions Vary with Age and Between Breeding and Wintering Grounds

The uropygial secretions of some bird species contain volatile and semivolatile compounds that are hypothesized to serve as chemical signals. The abundance of secretion components varies with age and season, although these effects have not been investigated in many species. We used solid-phase microextraction headspace sampling and solvent extraction coupled with gas chromatography-mass spectrometry to detect and identify volatile and semivolatile chemical compounds in uropygial secretions of gray catbirds (Dumetella carolinensis). We identified linear and branched saturated carboxylic acids from acetic (C2) through hexacosanoic (C26); linear alcohols from decanol (C10) through docosanol (C22); one aromatic aldehyde; one monounsaturated carboxylic acid; two methyl ketones; and a C28 ester. We tested for the effect of age on signal strength and found that juvenile birds produced greater amounts of volatile C4 through C7 acids and semivolatile C20 through C26 acids, although the variation among individuals was large. Adult birds displayed small concentrations and minimal individual variation among volatile compounds, but produced significantly higher levels of long-chain linear alcohols than juvenile birds. We tested for the effects of season/location by sampling adult catbirds at their Ohio breeding grounds and at their Florida wintering grounds and found that the heaviest carboxylic acids are significantly more abundant in secretions from birds sampled during winter at the Florida site, whereas methyl ketones are more abundant in birds sampled during summer on the Ohio breeding grounds. We observed no effect of sex on semivolatile compounds, but we found a significant effect of sex on levels of carboxylic acids (C4 through C7) for juvenile birds only.

The Ossification of the Pectoral Girdle and Wing Skeleton of the Quail (Coturnix coturnix japonica)

The onset of ossification centres of the pectoral girdle and wing skeleton of the quail (Coturnix coturnix japonica) has been studied in embryos and juvenile birds, which were sampled daily from the 4th day of incubation up to the 12th day after hatching. Specimens, which were cleared and were stained with Alcian Blue and Alizarin Red S, were examined at the stereomicroscope. The furcula ossified with intramembranous ossification at the 7th day of incubation. The first centres of perichondral ossification in the scapula and the coracoid bones were observed at the 7th day of incubation. In the humerus, radius and ulna, perichondral ossification was observed at the 6th day of incubation. The carpal bones were ossified between the 8th and 10th day of the post-hatching period. The 2nd metacarpal bone began to ossify at the 6th day of the post-hatching period, whereas the 3rd and 4th metacarpal bones were ossified at the 7th day of incubation. At the 9th day of incubation, ossification was observed in the 1st phalanx of the alular digit and in the phalanges of the major digit. The 2nd phalanx of the alular digit began to ossify at the 12th, whereas the phalanx of the minor digit at the 14th day of incubation. The data presented here provide useful baseline information on the normal sequential pattern of ossification in the pectoral girdle and wing skeleton in this species.