Thrush Species Research Articles

Frugivory and habitat use by thrushes (Turdus spp.) in a suburban area in south Brazil

Thrushes (Turdus spp., Turdidae) are among the most common frugivorous birds in urban areas around the world, where they disperse the seeds of a variety of plant species. We studied the abundance, habitat use, foraging behavior and diet of four thrush species (Turdus rufiventris, T. amaurochalinus, T. leucomelas, and T. albicollis) in a suburban area in south Brazil. Abundance, habitat use and foraging behavior were based on birds surveyed along a 3,240 m transect crossing open (formed by lawns, streets, and buildings) and forested areas. Diet was based on fecal samples collected from mist-netted birds. Turdus rufiventris was the most abundant species, followed by T. amaurochalinus, T. leucomelas, and T. albicollis. All species used forest fragments more frequently than expected by chance. A total of 91.8% (n = 147) of the fecal samples contained fruit remains, while 42.2% contained only animal matter. Most of the foraging records were on the ground, where birds got mainly invertebrates. Fruits and invertebrates were eaten more frequently in open than in forested areas. A total of 25 seed morfospecies were found in the droppings, including five exotic plant species. Thrushes overlapped widely in the fruit composition of their diets. The high abundance and degree of frugivory, coupled with the frequent use of forest patches, indicate that thrushes are among the great bird contributors to the seed dispersal occurring in urban forest patches, potentially influencing the vegetation dynamics of such habitats so important for the maintenance of the biodiversity in urban areas.

Universal Features in the Singing of Birds Uncovered by Comparative Research

Aside from some exceptions, songbird species differ in the structure of their singing and usually also in the size and performance mode their song repertoires. In the past, most studies concentrated on the species specific differences of singing, and thereby contributed to a better understanding of their diversity. In our approach, however, we focussed on the opposite perspective; i.e. we investigated whether and how far songbirds share structural song properties. To have a solid data base we focussed on four species of thrushes which were famous for their large vocal repertoires. The two Asian bird species were Oriental Magpie Robins (Copsychus saularis) and Shama Thrushes (Copsychus malabaricus), the two European species the Common Nightingale (Luscinia megarhynchos) and the Thrush Nightingale (Luscinia luscinia). The latter were incorporated into a sample 40 other European songbird species (Table 1) serving as a framework for our comparative approach (Figure 2, 4). Besides well-known differences among species, our analyses of song material yielded some remarkably similar relationships between structural and functional song properties, which often were shared even by unrelated species. In particular measures of song durations were usually related to song application during vocal interaction. And, individual variation of song duration was mainly a result of differences in syllable repetition within trilled song sections. Although some of these findings were predicted already by former studies (see Todt, 2004), their essentials can be based now on profound data sets of detailed measurement.Keywords: European Thrushes, Asian Thrushes, Copsychus saularis, C. malabaricus, song structure, signal lengths.doi: 10.3126/on.v6i1.1648Our Nature (2008)6:1-14

A Fifteen-year Study of Fall Stopover Patterns of Catharus Thrushes at an Inland, Urban Site

Abstract Little is known about how landbirds use urban habitats as migratory stopovers despite increasing urbanization in North America and the importance of the migratory period to annual survival of birds. I examined 15 years of autumn stopover data for three species of migratory Catharus thrushes from an urban natural area in metropolitan Detroit, Michigan, USA. The majority of birds were in good condition on first capture with 59% having more than a just a trace of fat, a higher proportion than reported for passerines at other fall stopover sites. Condition was similar among species, and there was little difference in fat class or mass between age groups. A linear regression of the condition of each bird at first capture and time of capture indicated positive diurnal mass gains in two species and mass loss in the third. Fourteen percent of thrushes banded were recaptured. Lean birds were not more likely to be recaptured than fatter birds and, among recaptured birds, there was no difference in stopover...

Systematics of Zoothera thrushes, and a synthesis of true thrush molecular systematic relationships

The true thrushes (Turdinae; Sibley and Monroe, 1990) are a speciose lineage of songbirds, with a near-cosmopolitan distribution. Following the systematic placement of true thrushes as a close relative of Old World flycatchers and chats (Muscicapinae) by the DNA–DNA hybridization work of Sibley and Ahlquist (1990), a number of molecular systematic studies have focused on various aspects of true thrush relationships. These studies have included phylogenetic assessments of genera membership in true thrushes, assessments of relationships among and within true thrush genera, and the recognition of ‘‘new” species (Bowie et al., 2003, 2005; Outlaw et al., 2003; Voelker and Spellman, 2004; Klicka et al., 2005; Miller et al., 2007; Voelker et al., 2007). Despite improved hypotheses of true thrush relationships, several problems remain. One problem involves several genera that are either monotypic (Hylocichla, Ridgwayia, Chlamydocaera), that contain just a few species (Cochoa, Sialia, Neocossyphus), or that appear to be distantly related to other genera (Sialia, Myadestes, Neocossyphus). While each of these genera have been phylogenetically placed within well supported true thrush subclades (Klicka et al., 2005), their sister relationships are not well supported within those clades. This issue might be attributable to a lack of dense taxon sampling across true thrush species, in previous analyses. Another problem involves the use of improper or ‘‘too distant” outgroups, which can affect resolution within single genera. For example, in a study of species relationships within the genus Catharus, Outlaw et al. (2003) used as outgroups two species each from the genera Turdus and Zoothera. It has subsequently been shown that neither was an appropriate genus to root Catharus, as both are distantly related (Klicka et al., 2005). More recently, Miller et al. (2007) used a single member of the genus Sialia to root their analyses of the genus Myadestes, despite both morphological and molecular analyses which suggested that Neocossyphus is probably a close relative, if not the sister taxon to Myadestes (Ames, 1975; Olson, 1989; Pasquet et al., 1999; Klicka et al., 2005).

Prevalence of avian-associated Borrelia burgdorferi s.l. genospecies in Ixodes ricinus ticks collected from blackbirds ( Turdus merula) and song thrushes ( T. philomelos)

Between May and September of 2002, forest passerine birds and immature Ixodes ricinus ticks infesting them were surveyed for infection with Borrelia burgdorferi s.l. in a sylvatic habitat in west-central Poland. A total of 738 feeding I. ricinus ticks were recovered from 114 birds belonging to 9 species. The majority of ticks (65.7%) were collected from two thrush species, the blackbird ( Turdus merula) and the song thrush ( T. philomelos). Since only the two Turdus species proved to be parasitized by Borrelia-infected ticks, this study focused mainly on these birds. Immature ticks were removed from 53 of the 54 captured thrushes. A total of 304 partially or fully engorged ticks (110 larvae and 194 nymphs), and 53 bird-derived blood samples were tested for borreliae. B. burgdorferi s.l. DNA was detected by PCR in 11% of the larval ticks and in 7.2% of the nymphs. The PCR-positive ticks were found on 8 of 53 tick-infested thrushes. B. garinii and B. valaisiana accounted for 88.5% and 11.5% of the infections detected in Borrelia-positive ticks, respectively. Only one out of 53 of Turdus blood samples were PCR-positive for borreliae. The blood-positive thrush was infected with B. burgdorferi s.s. B. afzelii was the most frequently identified genospecies in PCR-positive questing I. ricinus ticks, followed by B. valaisiana (89% and 11%, respectively). The absence of B. afzelii infection in ticks feeding on passerine birds, despite its strong predominance in local questing nymph populations, indicates that avian hosts are not reservoirs of this genospecies and consequently that the rodent-adapted B. afzelii is negatively selected in ticks feeding on these hosts. These results validate the concept of some avian-associated genospecies within the B. burgdorferi s.l. complex and demonstrate that thrush species may support the circulation of B. garinii and B. valaisiana under natural conditions.

Wingbeat frequency and flap-pause ratio during natural migratory flight in thrushes

Powered flapping flight has evolved independently in many different taxa. For flapping fliers, wingbeat parameters such as frequency and amplitude are the primary determinants of these animals' energetic expenditure during flight. Here we present data on wingbeat frequency and amplitude for three New World thrush species during 15 entire nocturnal migratory flights over the Midwestern United States. Using continuous (non-pulsing) radio transmitters, we were able to measure wingbeat frequency and relative amplitude of wingbeats as well as the characteristics of flap-pauses. Contrary to previous telemetric findings, all of the individuals we followed used both flapping-only and flap-pause flight. During migratory flights, wingbeat frequency, effective wingbeat frequency, and amplitude were highest during initial ascent. Effective wingbeat frequency and amplitude were lowest during final descent. We show that identification of species based solely on characteristics of the wingbeat e.g., during radar studies, can be difficult because variables such as wingbeat frequency and amplitude, wingbeat pausing, and pattern of beats and pauses vary between individuals of the same species and even within individual flights. We also show that observed wingbeat frequencies were lower than those predicted by theoretical models. We speculate that this may be because theoretical predictions are generally based on (1) data from larger birds and (2) data from diurnal flights. We found that diurnal wingbeat frequencies of thrushes were generally higher than were those during nocturnal migratory flight. Finally, we suggest that rather than remaining at a single altitude during flight or climbing slightly as theoretical models predict, thrushes often moved up and down in the air column, perhaps searching for favorable atmospheric conditions.

Two thrush species as dispersers of Miconia prasina (Sw.) DC. (Melastomataceae): an experimental approach

We carried out a seed germination experiment using two thrush species in captivity. We compared the number of germinated seeds and germination time of control seeds (manually removed from fruits) and ingested seeds of Miconia prasina by two bird species, Turdus albicollis and T. amaurochalinus, and also compared retention times of seeds by both thrush species. Control seeds germinated more frequently than those ingested for one species, T. albicollis. The germination time of ingested seeds by T. amaurochalinus was similar to the control seeds but seeds ingested by T. albicollis took longer to germinate than the controls. Both thrush species had a similar seed defecation pattern. The cumulative number of defecated seeds increased by 2 hours after fruit ingestion. At the end of the first 30 minutes both species had already defecated approximately 50% of the seeds ingested Our results suggest that both species could act as disperser agents of M. prasina.

Eggshell colour does not predict measures of maternal investment in eggs of Turdus thrushes

The striking diversity of avian eggshell colour has long fascinated biologists. Recently, it has been proposed that the blue-green colour of some eggs may function as a post-mating sexually selected signal of female phenotypic quality to their mates to induce higher allocation of paternal care. It has been suggested that maternally deposited yolk carotenoids may be the specific aspect of reproductive quality that the female is signalling via eggshell colour. We use the known properties of the thrush visual system (Turdus sp.) to calculate photon capture for the four single cone photoreceptors, and the principal member of the double cone class for eggs in clutches of two introduced European thrush species (Turdus merula and Turdus philomelos) in New Zealand. We show that differences in the avian-perceived colours of individual eggs are not consistently correlated with different measures of maternal investment in the egg. Given the growing extent of the knowledge between maternal quality, parental investment and eggshell pigmentation across avian taxa, we encourage the use of avian perceptual modelling for testing alternative non-signalling explanations for the structural and physiological basis of these relationships.

Habitat Partitioning of Four Sympatric Thrush Species at Three Spatial Scales on a Managed Forest in West Virginia

AbstractFour thrush species are sympatric in the central Appalachians: Veery (Catharus fuscescens), Hermit Thrush (C. guttatus), Wood Thrush (Hylocichla mustelina), and American Robin (Turdus migratorius). The four species often nest near one another, which suggests that habitat partitioning may have developed to minimize past interspecific competition. Our objectives were to determine which specific characteristics of nesting habitat were partitioned among the species and to evaluate the relationship of these characteristics to nest survival. We monitored nests and sampled habitat variables at three spatial scales: nest substrate, nest site, and territory. A multivariate analysis of variance indicated a difference (P < 0.01) in the nest sites of all species and in each pairwise species contrast. An analysis of variance and Fisher’s exact tests detected differences (P < 0.05) among species in 21 of 36 variables measured. Classification tree analysis correctly classified nests by species at a rate better than would be expected at random. Habitat partitioning among the four thrush species occurred at all three scales sampled, with the most important partitioning variables being nest height, distance-to-edge, sapling density, and elevation. Mayfield logistic regression found a positive relationship (P < 0.05) between decreasing nest height and American Robin nest survival. Overall, nest survival was similar among the four thrush species examined, and most of the variables that we measured were unrelated to survival.Partition de l’habitat de quatre espèces sympatriques de grives à trois échelles spatiales dans une forêt aménagée de la Virginie-Occidentale

A nondestructive method for extracting maternally derived egg yolk carotenoids

Maternally deposited carotenoids are a prominent component of egg yolk and are vital for the development and growth of the embryo. In most studies of avian yolk carotenoids, eggs are destructively sampled and this may limit both the number of clutches studied and the research questions addressed. We describe an empirical field trial for a nondestructive biopsy method to extract small samples (0.05 ml) of egg yolk for high- performance liquid chromatography (HPLC) analysis of yolk carotenoid concentrations. We sampled 180 clutches (N = 44 biopsies) of two species of introduced thrushes (genus Turdus) from agricultural habitats in central North Island, New Zealand. Once the protocol was established, all biopsied eggs from clutches that were not depredated or deserted before candling were found to be developing normally after 3-5 d of incubation (N = 28) and all hatched. Biopsy samples (>0.02 g) produced concentrations of yolk carotenoids (and variances) that were statistically indistinguishable from whole yolk destructive samples. In addition, our samples (>0.02 g) confirmed previously reported differences in yolk carotenoid concentrations between the two thrush species and revealed a significant decline in yolk carotenoid concentration with laying order. Further examination of how variability in yolk carotenoid concentration and identity influences offspring sex, success, and survival or, later in life, reproductive success and ability to efficiently incorporate dietary carotenoids into both integument and immune tissues will require larger sample sizes. Studies to date have been restricted by the number of destructive samples that investigators are willing (or permitted) to obtain from wild species. Thus, we hope that our nondestructive method of sampling yolk will promote further examination of the links between carotenoid uptake from the environment and maternal investment in the avian yolk.

Occurrence and nest survival of four thrush species on a managed central Appalachian forest

The wood thrush ( Hylocichla mustelina Gmelin) is a species of concern in the central Appalachians, and is sympatric there with three related species, the American robin ( Turdus migratorius Linnaeus), hermit thrush ( Catharus guttatus Pallas), and veery ( Catharus fuscescens Stephens). Our objectives were to quantify use of mature forests and areas subjected to even-aged harvesting and partial harvesting by these four species by measuring their frequency of occurrence, nest survival, and nest site characteristics. We also compared microhabitat characteristics among the landcover types. During 2001–2003 we conducted point count surveys, monitored nests, and collected nest habitat data on a managed forest in West Virginia. Land cover was digitized into five categories: deciduous and mixed mature forest, deciduous and mixed partial harvest, and even-aged regeneration harvest. Chi-square goodness-of-fit analysis with Bonferroni 95% confidence intervals indicated that deciduous partial harvests were more likely to be inhabited by wood thrushes. The other three species were less likely to occur in deciduous partial harvests, and veery had lower nest survival in partial harvests than in mature forest. Contrary to many published descriptions that suggest thrushes will not nest in even-aged harvests, a small number of all species but hermit thrushes did nest in this cover type, often near a residual canopy tree. Hermit thrushes were less likely to inhabit mature deciduous forest, even-aged harvests, and harvested edges but chose nesting areas in mature mixed forest that was disturbed by road building and the seeding of landings and skid trails >10 years ago. Microhabitat characteristics of landcovers did not differ overall. Our results suggest a relationship with partial harvesting that is positive for wood thrush but negative for the other three species.

HABITAT PARTITIONING OF FOUR SYMPATRIC THRUSH SPECIES AT THREE SPATIAL SCALES ON A MANAGED FOREST IN WEST VIRGINIA

Abstract Four thrush species are sympatric in the central Appalachians: Veery (Catharus fuscescens), Hermit Thrush (C. guttatus), Wood Thrush (Hylocichla mustelina), and American Robin (Turdus migratorius). The four species often nest near one another, which suggests that habitat partitioning may have developed to minimize past interspecific competition. Our objectives were to determine which specific characteristics of nesting habitat were partitioned among the species and to evaluate the relationship of these characteristics to nest survival. We monitored nests and sampled habitat variables at three spatial scales: nest substrate, nest site, and territory. A multivariate analysis of variance indicated a difference (P < 0.01) in the nest sites of all species and in each pairwise species contrast. An analysis of variance and Fisher’s exact tests detected differences (P < 0.05) among species in 21 of 36 variables measured. Classification tree analysis correctly classified nests by species at a rate better ...

Seasonal Differences in Immunological Condition of Three Species of Thrushes

Abstract Migratory birds are exposed to a diverse pathogen fauna by virtue of their long-distance travels. Although the immune system is an organism's primary defense against pathogenic microorganisms, few studies have investigated avian immune function during migration, much less shown seasonal differences in immune function. We describe the immunological condition of three intercontinental migratory species, Swainson's Thrush (Catharus ustulatus), Veery (C. fuscescens), and Wood Thrush (Hylocichla mustelina) during spring migration. In addition, we compare their immunological condition with conspecifics captured during fall migration and during the breeding season to provide a frame of reference for the spring immunological data. Measures of immunological condition presented include total leukocyte count, heterophil:lymphocyte (H:L) ratio, heterophil and lymphocyte counts, hematocrit, and IgG titers. In addition, we assessed each bird's energetic condition by measuring body mass and calculating a size-corrected condition index. Migrating birds had lower leukocyte and lymphocyte counts, lower hematocrit, reduced fat stores, and higher H:L ratios relative to nonmigrating individuals sampled during the breeding season. We also found that birds sampled during spring migration had lower lymphocyte counts and reduced fat stores, and higher heterophil counts and H:L ratios than fall migrants. Our results suggest that migrating birds are immunocompromised compared with conspecifics during the breeding season. Furthermore, compared with conspecifics sampled after a shorter overland flight, migrants sampled after crossing the Gulf of Mexico exhibited higher H:L ratios, which is indicative of heightened energetic stress.

Rainforests as concert halls for birds: Are reverberations improving sound transmission of long song elements?

In forests reverberations have probably detrimental and beneficial effects on avian communication. They constrain signal discrimination by masking fast repetitive sounds and they improve signal detection by elongating sounds. This ambivalence of reflections for animal signals in forests is similar to the influence of reverberations on speech or music in indoor sound transmission. Since comparisons of sound fields of forests and concert halls have demonstrated that reflections can contribute in both environments a considerable part to the energy of a received sound, it is here assumed that reverberations enforce also birdsong in forests. Song elements have to be long enough to be superimposed by reflections and therefore longer signals should be louder than shorter ones. An analysis of the influence of signal length on pure tones and on song elements of two sympatric rainforest thrush species demonstrates that longer sounds are less attenuated. The results indicate that higher sound pressure level is caused by superimposing reflections. It is suggested that this beneficial effect of reverberations explains interspecific birdsong differences in element length. Transmission paths with stronger reverberations in relation to direct sound should favor the use of longer signals for better propagation.

Behaviour of African turdid hosts towards experimental parasitism with artificial red‐chested cuckoo Cuculus solitarius eggs

The red‐chested cuckoo Cuculus solitarius parasitises many passerines in Africa, but some common species sympatric with this brood parasite are rarely used as hosts. We tested the responses of three turdid hosts to parasitism with artificial cuckoo eggs. The kurrichane thrush Turdus libonyana, which is not regularly parasitized by the cuckoo, rejected 60% of mimetic model eggs and 81% of non‐mimetic eggs. We observed female thrush behaviour during the first visit after parasitism, and thrushes appeared to be initially fooled by mimetic eggs in completed clutches in all cases, and incubated. By contrast, in half of the experiments with non‐mimetic eggs, these were ejected by the thrushes, with the host grasping the egg and flying away with it. The time spent nest checking prior to ejection was only one third of the time spent nest checking when females decided to incubate the clutch, suggesting that females were immediately aware of a foreign egg in the nest. By contrast, southern olive thrushes T. olivaceous rejected all non‐mimetic and accepted all mimetic model eggs, whereas cape robins Cossypha caffra accepted all model eggs, irrespective of whether or not they were mimetic. Our results support the hypothesis that rejection behaviour in these two thrush species evolved as a defence against interspecific nest parasitism, with thrushes appearing to be ahead in this particular host‐parasite arms race. The cape robin, by contrast, appears not to reject cuckoo eggs, either because it is to unable to recognize them, or because the costs associated with removal may be too high.

Autumn migration of thrushes over eastern Finland: A comparison of visible migration and ringing recovery patterns

The migration of thrushes Turdus spp over eastern Finland was investigated using data from 4,482 foreign recoveries of five species ringed in Finland between 1913 and 2001, and records of visible migration of nearly 28,000 thrushes observed during diurnal autumn movements between 1996 and 2001. Ringing recoveries suggested that the main autumn direction of movement from eastern Finland is southwest for Redwings T iliacus, Fieldfares T pilaris and Song Thrushes T philomelos, west‐southwest for Blackbirds T merula and south for Mistle Thrushes T viscivorus. Visible migration records for Mistle Thrushes seemed to correspond well with ringing recoveries, but the other thrush species showed different directions of movement, mainly towards the west‐northwest or along a west‐northwest to east‐southeast axis, possibly due to the influence of lake districts as guidelines. The available wind data showed that the thrushes flew in an inappropriate west‐north west direction on most peak movement days regardless of wind direction, though some correspondence with moderately strong head or cross winds was evident. The majority of foreign recoveries of thrushes ringed in Finland were found between western and southern Europe but a small proportion of birds have also been recovered from southeast and northwest sectors. The rather irregular migratory behaviour of Redwings and Fieldfares is exemplified by the ringing recoveries of individual birds, or birds from the same brood, in entirely different areas during subsequent winters. This might be explained by drift during migration, movements during hard weather or intense nomadic behaviour.

The Karoo Thrush (Turdus smithi Bonaparte 1850), a southern African endemic

The Olive Thrush (Turdus olivaceus) species complex is characterised by striking geographical phenotypic variation. Recent consensus has been to recognise three assemblages (1) the olivaceus group restricted to southern Africa, (2) the swynnertoni group of the Zimbabwean and southern Malawi highlands and (3) the abyssinicus group of the montane highlands of eastern and central Africa. We re-examined the status of taxa in the olivaceus group of southern Africa, with specific reference to the central-western taxon T. o. smithi using both morphological and molecular evidence. Sequence divergence between T. o. smithi and other members of the olivaceus group averages 3.5% for the cytochrome-b gene and 4-4.5% for the NADH sub-unit 3 gene of the mitochondrial DNA. There is also both morphological (biometric and plumage) and molecular support for the recognition of T. smithi as a separate species, the common name of which we suggest should be Karoo Thrush.

Chewing Louse Distributions on Two Neotropical Thrush Species

Abstract We sampled lice from 2 species of Neotropical thrushes, Turdus assimilis, the white-throated robin, and T. grayi, the clay-colored robin, to document the prevalence, intensity, abundance, and species richness on each host. Sampling was conducted in 1999 in the Coto Brus Valley of southern Costa Rica using a modified dust-ruffling technique. The prevalence of lice was high—lice were recovered from 93% (n = 14) of T. grayi and 86% (n = 22) of T. assimilis individuals sampled. Observed prevalence and generic-level louse diversity were similar to those reported for T. migratorius, the American robin, in Newfoundland, Canada, although T. assimilis and T. grayi tended to have higher proportions of lice belonging to the suborder Amblycera. Turdus grayi hosted marginally more louse species (mean = 1.6, SD = 0.8) and had marginally higher louse abundance (mean = 33.9, SD = 27.9) than T. assimilis (mean = 1.1, SD = 0.6 and mean = 16.5, SD = 17.3, respectively), although T. grayi and T. assimilis are closel...

Feeding Activity and Seasonal Changes in Prey Composition of urban Peregrine FalconsFalco peregrinus

Despite the increasing populations of Peregrine Falcons in European cities, detailed quantitative studies of their diet composition and feeding activity in urban environments are rare. The results from observations in Warsaw have added to the knowledge of the feeding ecology of urban raptors. In 2000 and 2001 the same pair of Peregrines bred successfully in nest boxes situated on two different buildings in the city centre, rearing three and four chicks in the respective years. During the breeding seasons from hatching to fledging, the nests were monitored with a video camera. Only diurnal observations were used in the detailed analysis of feeding activity — 428 h in 2000 (33 days) and 384 h (24 days) in 2001. Two peaks of parental activity were noted: in the morning and in the afternoon. Additional data collected in 2000 showed that the falcons also fed their young at night. In 1998–2001 486 prey remains were collected on the buildings occupied by the Peregrines. In Warsaw these falcons preyed most often on Feral Pigeons (32%), and also on various thrush species (23.5%), Skylarks (8%) and Corncrakes (5.6%). Seasonal variations in prey composition were identified. During the spring and autumn migrations, the proportion of pigeons in the falcons' diet was 10–19%, while in summer and winter it was over 40%. The trend was reversed with regard to migrant species, which were prevalent in the diet in spring and autumn, but less numerous in summer and winter.

Development of restoration techniques for Hawaiian thrushes: Collection of wild eggs, artificial incubation, hand-rearing, captive-breeding, and re-introduction to the wild

From 1995 to 1999, two species of endemic Hawaiian thrushes, `Oma`o (Myadestes obscurus) and Puaiohi (M. palmeri), were captive-reared and re-introduced into their historic range in Hawai`i by The Peregrine Fund, in collaboration with the U.S. Geological Survey–Biological Resources Division (BRD) and the Hawai`i State Department of Land and Natural Resources. This paper describes the management techniques that were developed (collection of wild eggs, artificial incubation, hand-rearing, captive propagation, and release) with the non-endangered surrogate species, the `Oma`o; techniques that are now being used for recovery of the endangered Puaiohi. In 1995 and 1996, 29 viable `Oma`o eggs were collected from the wild. Of 27 chicks hatched, 25 were hand-reared and released into Pu`u Wa`awa`a Wildlife Reserve. Using the techniques developed for the `Oma`o, a captive propagation and release program was initiated in 1996 to aid the recovery of the endangered Puaiohi. Fifteen viable Puaiohi eggs were collected from the wild (1996–1997) to establish a captive breeding flock to produce birds for re-introduction. These Puaiohi reproduced for the first time in captivity in 1998 (total Puaiohi chicks reared in captivity 1996–1998 = 41). In 1999, 14 captive-bred Puaiohi were re-introduced into the Alaka`i Swamp, Kaua`i. These captive-bred birds reproduced and fledged seven chicks in the wild after release. This is the first endangered passerine recovery program using this broad spectrum of management techniques (collection of wild eggs, artificial incubation, hand-rearing, captive-breeding, and release) in which re-introduced birds survived and bred in the wild. Long-term population monitoring will be published separately [BRD, in preparation]. Zoo Biol 19:263–277, 2000. © 2000 Wiley-Liss, Inc.