Pairs Of Birds Research Articles

First sighting of a pair of Ryukyu robin Larvivora komadori Temminck, 1835 (Aves, Passeriformes) during breeding season on Jeju Island, Republic of Korea: a nesting attempt?

The Ryukyu robin (Larvivora komadori Temminck, 1835) is an endemic inhabitant of the Ryukyu Archipelago, Japan. In 2018, we made several birding excursions to Jeju Island, Republic of Korea. Within the 1100 Altitude Wetland protected area on May 28 and May 30 we encountered a pair of birds, which, according to reference literature and bird guides we identifi ed as Larvivora komadori. That was the fi rst visual sighting of the Ryukyu robin during the breeding season on Jeju Island, which is separated from the nearest breeding site by more than 200 kilometers of open sea. This fact can be regarded as a potential ability for this endemic island species to spread to new islands. Possible pathways for natural introduction of the Ryukyu

Taste Preferences in Broilers: Effect of Age, Delivery Matrix, and Number of Chickens per Pen on Selection and Consumption Behaviour

Due to substantial differences between studies, the understanding of avian taste perception remains incomplete. Also, studies on chicken taste preferences have mainly focused on measuring consumption differences, neglecting consumption behaviour patterns. This study investigated how age, the compound delivery matrix, and the number of birds per pen affect broiler chicken preferences and consumption behaviour, and established their preference values for four taste compounds. Ninety-six one-day-old male broiler chickens (Ross 308) were divided into two age groups (initial: days 7–23; final: days 26–42), with two compound delivery matrices (water or ground wheat) and two numbers of birds (one or two chickens per pen), following a 2 × 2 × 2 factorial design. Four taste compounds (sucrose, monosodium glutamate (MSG), L-lysine, and calcium carbonate) were tested at different concentrations. Preferences were assessed at 2, 4, and 8 h post-test, along with recording various behavioural parameters. Initial-stage birds showed higher (p < 0.001) preference values, time of approach (TA), number of bouts (NB), duration of bouts (DB), and number of pecks (NP) than final-stage birds. Birds exposed to a water matrix also exhibited higher (p < 0.001) preference and NB, while those exposed to a ground wheat matrix showed a higher (p < 0.001) NP. Pens with a pair of birds had a higher (p < 0.003) 2 h preference, TA, NB, DB, and NP, than pens with a single chicken. Chickens showed significant preference values for 100 mM sucrose at 2 h (p = 0.025), 150 mM MSG at 4 h (p = 0.026) and 8 h (p = 0.013), and 300 mM MSG at 2 h (p = 0.013). We concluded that all the variables evaluated influence broilers’ taste preferences and consumption behaviour during selection tests. Future studies should prioritize including chickens in the initial stage of the production cycle, testing them in pairs or groups, and delivering compounds via a liquid matrix.

Aggressiveness predicts dominance rank in greylag geese: mirror tests and agonistic interactions.

Individual differences in aggressiveness, if consistent across time and contexts, may contribute to the long-term maintenance of social hierarchies in complex animal societies. Although agonistic interactions have previously been used to calculate individuals' positions within a dominance hierarchy, to date the repeatability of agonistic behaviour has not been tested when calculating social rank. Here, we examined the consistency and social relevance of aggressiveness as a personality trait in a free-flying population of greylag geese (Anser anser). For each individual, we quantified (i) aggressiveness using a standardized mirror stimulation test and (ii) dominance ranking based on the number of agonistic interactions won and lost in a feeding context. We found that individual differences in aggressiveness were significantly repeatable and that individuals' aggressiveness predicted their dominance rank position. The flock showed a robust and intermediately steep dominance hierarchy. Social rank was higher in paired birds, males and older birds, and most agonistic interactions occurred between individuals with moderate rank differences. We suggest that selection favours aggressiveness as a personality trait associated with resource acquisition and social rank, whereby a dominance hierarchy may increase the benefits of group living and reduce costs over conflict within dyads.

Constant light and pinealectomy disrupt daily rhythm in song production and negatively impact reproductive performance in zebra finches.

We assessed the circadian clock control of singing and reproductive performance in zebra finches. Experiment 1 examined changes in body mass, testis size, and plasma corticosterone and testosterone levels in male birds exposed to constant light (LL, 100lx) and constant darkness (DD, 0.5lx), with controls on 12L:12D (L = 100lx, D = 0.5lx). There was a significant increase in the body mass and testis size under LL and a decrease in testis size under the DD. Using a similar design, experiment 2 assessed the persistence of the circadian rhythm in singing along with activity-rest pattern in cohort I birds that were entrained to 12L:12D and subsequently released in DD or LL, and in cohort II birds that were entrained to 12L:12D and following pinealectomy were released in DD. Both activity and singing patterns were synchronized with the light phase under 12L:12D, free-ran with a circadian period under DD, and were arrhythmic under the LL. There was an overall decreased and increased effect on singing under DD and LL, respectively, albeit with differences in various song parameters. The pinealectomy disrupted both activity and singing rhythms but did not affect singing or the overall song features. Pinealectomized bird pairs also exhibited a significant reduction in their nest-building and breeding efforts, resulting in a compromised reproductive performance. These results suggest a circadian clock control of singing and more importantly demonstrate a role of the pineal clock in breeding behaviors, leading to a compromised reproductive performance in diurnal zebra finches.

NESTING BIOLOGY OF THE INDIAN SPARROW (PASSER INDICUS) IN THE FLATLANDS OF TASHKENT REGION

Observations on the nesting biology of the Indian sparrow were conducted in Boka district of Tashkent region. 392 nesting pairs of birds were found in a colony formed on the wall of a ravine on the bank of a waste water canal. All processesin 12 nests were monitored in orderto study the nesting biology of the Indian sparrow. Egg-laying of birds in the colony began on May 10 and continued until May 18. A total of 72 eggs were laid in reference nests

Interindividual distances and orientations of laying hens under 8 stocking densities measured by integrative deep learning techniques

Interindividual distances and orientations of laying hens provide quantitative measures to calculate and optimize space allocations for bird flocks. However, these metrics were often measured manually and have not been examined for different stocking densities of laying hens. The objectives of this study were to 1) integrate and develop several deep learning techniques to detect interindividual distances and orientations of laying hens; and 2) examine the 2 metrics under 8 stocking densities via the developed techniques. Laying hens (Jingfen breed, a popular hen breed in China) at 35 wk of age were raised in experimental compartments at 8 different stocking densities of 3,840, 2,880, 2,304, 1,920, 1,646, 1,440, 1,280, and 1,152 cm2•bird-1 (3-10 hens per compartment, respectively), and cameras on the top of the compartments recorded videos for further analysis. The designed deep learning image classifier achieved over 99% accuracy to classify bird's perching status and excluded frames with bird perching to ensure that all birds analyzed were on the same horizontal plane, reducing calculation errors. The YOLOv5m oriented object detection model achieved over 90% precision, recall, and F1 score in detecting birds in compartments and can output bird centroid coordinates and angles, from which interindividual distances and orientations were calculated based on pairs of birds. Laying hens maintained smaller minimum interindividual distances in higher stocking densities. They were in an intersecting relationship with conspecifics for over 90% of the time. The developed integrative deep learning techniques and behavior metrics provide animal-based measurement of space requirement for laying hens.

Видовой состав хищных птиц Бузулукского бора (Оренбургская и Самарская области, Россия) по результатам наблюдений в прошлом и настоящем

Buzuluk pine forest is a unique pine massif with a total area of 111,118 hectares, which is located entirely in the steppe biome on the border of the Orenburg and Samara regions, in the southeastern part of the Russian Plain. This report provides some information about threatened and endangered raptors of the Buzuluk pine forest for a relatively long period of time. It uses data by scientist and ornithologist E.P. Knorre collected between 1928 and 1941, present time observations carried out since 2000 to the present, and published data by other researchers who have visited Buzuluk pine forest starting from the beginning of the 21st century. Most observations by E.P. Knorre were associated with the Pine Barrens Experimental Forestry in the Orenburg region, where “Buzuluk pine forest” Nature Reserve (10,503 hectares) existed at the time. In his unpublished monumental report “Qualitative inventory of birds and animals of the Buzuluk Pine Forest State Nature Reserve”, discovered in the archive of the current “Buzuluk Pine Forest” National Park relatively recently, E.P. Knorre listed the following raptor species found in Buzuluk Pine Forest: Common Kestrel Falco tinnunculus (breeding) Red-Footed Falcon Falco vespertinus (breeding) Eurasian hobby Falco subbuteo (breeding) Saker Falcon Falco cherrug (breeding) Osprey Pandion haliaetus (highly likely breeding) European Honey-Buzzard Pernis apivorus (breeding) Black Kite Milvus migrans (breeding) White-Tailed Sea-Eagle Haliaeetus albicilla (breeding) Short-Toed Snake-Eagle Circaetus gallicus (breeding) Western Marsh-Harrier Circus aeruginosus (breeding) Pallid Harrier Circus macrourus (breeding) Eurasian Sparrowhawk Accipiter nisus (breeding) Northern Goshawk Accipiter gentilis (breeding) Eurasian Buzzard Buteo buteo (breeding) Rough-Legged Buzzard Buteo lagopus (wintering) Greater Spotted Eagle Aquila clanga (breeding) Eastern Imperial Eagle Aquila heliaca (breeding) Golden Eagle Aquila chrysaetos (breeding) Eurasian Scops Owl Otus scops (breeding) Eurasian Eagle Owl Bubo bubo (breeding) Tawny Owl Strix aluco (breeding) Ural Owl Strix uralensis (breeding) Little Owl Athene noctua (common in autumn, the status is unclear) Northern Long-Eared Owl Asio otus (breeding) Short-Eared Owl Asio flammeus (breeding) Since the beginning of the 21st century, occurrence of most raptor species listed in report by E.P. Knorre was confirmed in the modern period of observations in Buzuluk Pine Forest. Nevertheless, such raptor species as Common Kestrel, Red-Footed Falcon, Saker Falcon, Osprey, Short-Toed Snake-Eagle, and Pallid Harrier were not recorded. Western Marsh-Harrier that once bred here was not found on the internal water lakes and swamps of the Buzuluk Pine Forest. As for the Strigiformes, Tawny Owl, Ural Owl and Northern Long- Eared Owl were recorded more frequently today. The previously breeding Eurasian Scops-Owl and Short-Eared Owl in the inner sections of the pine forest were not recently found here. Present-day breeding of Eurasian Eagle Owl requires additional confirmation. The finds of Little Owl, included in the Knorre’s report as autumn migrant, have not been confirmed yet. At the same time, new raptor species have been registered in the Buzuluk Pine Forest. These include Peregrine Falcon (Falco peregrinus; single individual was observed in summer: Barabashin, 2001), Hen Harrier (Circus cyaneus; a pair of birds in May: our data), Montagu’s Harrier (Circus pygargus; single bird in May: our data), Levant Sparrowhawk (Accipiter brevipes; single bird in May: Morozov, Kornev, 2009). According to our observations, the wellbeing of such species as Greater Spotted Eagle, White-Tailed eagle, Golden Eagle, Short-Eared Owl, Western Marsh-Harrier, Montagu’s Harrier was influenced by the ongoing climate warming in the Buzuluk Pine Forest area, which was evident from raising average annual air temperatures and decreasing precipitation. According to observations by E.P. Knorre, another serious limiting factor in the past was transformation of the forest under the influence of extensive fires and uncontrolled logging of trees. Logging and fires in pre-Soviet times led to appearance of huge empty spaces, which were then penetrated by steppe vegetation from adjacent steppe areas. Steppe formation was responsible for the appearance of such species as Common Kestrel, Red-Footed Falcon, Pallid Harrier, Eastern Imperial Eagle across inner forest areas for some time. In the 1950s, the mass pine tree plantings and increased fire control led to restoration of the forest integrity and at the same time to disappearance of Common Kestrel, Red-Footed Falcon, Pallid Harrier, relocation of breeding pairs of Eastern Imperial Eagle to outer rims of the forest.

Анализ структурной организации сообщества крупных хищных птиц Ремдовского заказника

Анализ структурной организации сообщества крупных хищных птиц Ремдовского заказника

Hittite warā(i)-: ‘(bird) mate, companion’

The Hittite term warā(i)– is only found in Hittite bird oracle reports of early date (Middle Script). The first convincing interpretation of this term, as ‘pair’, was provided by Y. Sakuma in his doctoral dissertation on Hittite bird oracles (2009). An amendment to this interpretation can be proposed based on the consistent usage both in the plural (primarily) and in the singular (rarely), which shows that this term refers, rather, to one member of a pair at a time, thus a ‘mate, companion’ – namely of a pair of birds. The article thus proposes, moving from the semantics of ‘pair’, an improved translation ‘mate, companion’ for Hittite warā(i)– and discusses the attestations and passages of interest in the oracle reports. It is also suggested that the term is to be understood as an adaptation from Luwian, and possible connected forms are discussed. An appendix discusses a Hittite verb which may also be connected to the same root (although less securely), warasḫ-.

Egg production and endocrine profiles of female whooping cranes (Grus americana) maintained ex situ are improved in naturalized enclosures

Whooping cranes (Grus americana) are naturally seasonal breeders and rely on wetland habitats throughout the annual cycle. However, captive cranes are commonly housed in dry outdoor pens, which may lack key environmental stimuli that in turn compromise reproduction. Our study sought to first, assess seasonal patterns of reproductive hormones in successful versus non-successful bird pairs and second, determine endocrine responses to alterations in enclosure environments. Fecal samples were collected from eight crane pairs year-round for 3 consecutive years, once a week during non-breeding season and three times a week during the breeding season. During Year 1, all pairs were housed in traditional dry pens, whereas during January of Year 2 all pairs were moved to either new dry pens (control, n = 4) or ponded pens (wetland, n = 4) and remained in the same pen until the end of the study. Fecal samples were assessed for gonadal (year-round) and adrenal (breeding season only) hormones. Estrogen and progestagen metabolite concentrations were low during non-breeding season in all females. However, as birds transition into a breeding season, gonadal hormone concentrations significantly increased (p < 0.001) in laying females but not in non-laying individuals. Androgen metabolite concentrations during breeding seasons were higher (p < 0.001) in males paired with non-laying females, with no variations observed during non-breeding months and within birds of the same reproductive output. We observed significant effect of enclosure environment on ovarian function of female whooping cranes. Specifically, mean estrogen metabolite concentrations increased after birds were moved from dry pen to wetland enclosures (Year 1: 349.1 ± 83.4 ng/g feces; Year 2: 382.7 ± 82.9 ng/g feces; Year 3: 556.5 ± 85.4 ng/g feces, p = 0.008 and 0.019 respectively,), whereas those of the control females remained constant. Further, estrogen concentration assessed during breeding season of Year 3 in females housed in wetland pens was higher than birds housed in a dry pen (556.5 ± 85.4 vs 311.7 ± 85.12 ng/g feces; p = 0.019). The number of eggs laid increased in three of the four pairs housed in the wetland pens, while there was no change in egg production in control birds (9 vs. 2 combined number of eggs produced by all pairs in each respective group in Year 3). Finally, moving birds to an enclosure that mimic natural environment did not impact androgen or glucocorticoid excretion. The findings demonstrate that differences in gonadal hormone production between laying and non-laying whooping crane females exist primarily during the breeding season, and that a more natural environment can have a positive influence on ovarian function in female whooping cranes.

The role of divergent ecological adaptation during allopatric speciation in vertebrates

After decades of debate, biologists today largely agree that most speciation events require an allopatric phase (that is, geographic separation), but the role of adaptive ecological divergence during this critical period is still unknown. Here, we show that relatively few allopatric pairs of birds, mammals, or amphibians exhibit trait differences consistent with models of divergent adaptation in each of many ecologically relevant traits. By fitting new evolutionary models to numerous sets of sister-pair trait differences, we find that speciating and recently speciated allopatric taxa seem to overwhelmingly evolve under similar rather than divergent macro-selective pressures. This contradicts the classical view of divergent adaptation as a prominent driver of the early stages of speciation and helps synthesize two historical controversies regarding the ecology and geography of species formation.

Культово религиозные представления средневековых кочевников Южного Урала (на материалах погребального комплекса Уелги)

In the High Middle Ages in the multicultural environment of the nomads of the Ural-Kazakhstan steppes the necessity was maturing for entry into the area of a mono-religious spiritual space. Manichaeism, which appeared in Central Asia as the state religion of the Uyghur Khaganate, subsequently spread widely to the west among the Altai, East Kazakhstan and South Ural nomadic communities. This is indicated by vivid pictorial images (Nestorian — Christian cruciform plaques, scenes of Buddhist-Christian images and paired birds of the Tree of Life), which have become widespread in silver or polymetallic headset toreutics. This is clearly seen in the materials of the Uelgi burial complex. The reason for this process was not only in the indirect western expansion of the Uyghur Khaganate and a little later the Kyrgyz Khaganate, but in the unusual popularity of Manichaeism. It was the universal religion closest to the pagan Ugric-Tengrian pantheism. Consequently, it is no coincidence that the symbolism and involved images in visual practice include peculiar markers of Zoroastrianism, Christianity, Buddhism, and Manichaeism itself.

Effect of Dietary Supplemental Zinc on Laying Performance, Egg Quality, and Plasma Hormone Levels of Breeding Pigeons.

This study aimed to evaluate the dietary zinc requirement of parental pigeons for better laying and reproductive performance, egg quality, sex hormones, and mineral content in eggs. A total of 160 pairs of healthy American Silver King pigeons were randomly assigned to five treatments of eight replicate cages each with four pairs of birds per cage, and fed a basal diet without zinc supplementation or the basal diet supplemented with 30, 60, 90, and 120mg of zinc/kg (ZnSO4·7H2O). The experiment lasted for 45days, including two laying cycles. Results indicated the egg production rate (P = 0.081), egg shape index (P = 0.038), egg eggshell percentage (P = 0.070), and zinc and calcium contents (P < 0.01) tended to be affected or significantly affected by zinc addition. They increased quadratically with dietary zinc levels (P < 0.05). Besides, shell thickness (P = 0.069), plasma testosterone (P = 0.008), LH, and carbonic anhydrase contents (P < 0.05) tended to be affected or significantly affected by zinc addition. They increased linearly as dietary zinc level increased (P < 0.05). Compared with the control, 60mg/kg zinc addition increased egg production rate, egg shape index, zinc and calcium contents in eggshell, and plasma testosterone concentration in pigeons (P < 0.05), and tended to increase the eggshell percentage (P = 0.07). Besides, supplemental 120mg/kg zinc had higher shell thickness and LH content than control (P < 0.05), but had no difference with 60mg/kg zinc addition. In conclusion, the supplementation of zinc at the level of 60mg/kg to basal diet improved laying performance by increasing eggshell quality and sex hormone levels of breeding pigeons.

Being There. If the Pairing of the Birdwatchers Affects the Pairing of the Birds

The drives of inter-individual relationships within avian social groups are largely unexplored and relatively poorly understood, including how social landscapes affect the decisions of individuals within these groups. On a modest level, this study undertakes to expand this knowledge with an ornithological observation of temporary groupings among multiple aquatic species in response to the pairing of birdwatchers. More ambitiously, the study presumes the analogy between the social response of an avian community and the subliminal response of the human psyche to spatial stimuli. The number of bird pairs forming in flocks, coverts and rafts was consistently higher when the birds interacted with children teamed up in pairs than when solitary children interacted with the birds. Inadvertent social cues consequential to the extended duration of the focus, vigilance stimulation and subliminal messages affecting the neurological pathways in the brain and the social dynamics pertaining to proxemics are discussed as potential causes of this effect. Lastly, the structure of the paper mimics the lifetime of inventive ideas, which originate from a chaos of amorphous thought, then crystallize into a clarity of logical concepts open to elaboration, and eventually disperse into a similar semantic clutter as that from which they were born.

Maintenance and dissemination of avian-origin influenza A virus within the northern Atlantic Flyway of North America.

Wild waterbirds, the natural reservoirs for avian influenza viruses, undergo migratory movements each year, connecting breeding and wintering grounds within broad corridors known as flyways. In a continental or global view, the study of virus movements within and across flyways is important to understanding virus diversity, evolution, and movement. From 2015 to 2017, we sampled waterfowl from breeding (Maine) and wintering (Maryland) areas within the Atlantic Flyway (AF) along the east coast of North America to investigate the spatio-temporal trends in persistence and spread of influenza A viruses (IAV). We isolated 109 IAVs from 1,821 cloacal / oropharyngeal samples targeting mallards (Anas platyrhynchos) and American black ducks (Anas rubripes), two species having ecological and conservation importance in the flyway that are also host reservoirs of IAV. Isolates with >99% nucleotide similarity at all gene segments were found between eight pairs of birds in the northern site across years, indicating some degree of stability among genome constellations and the possibility of environmental persistence. No movement of whole genome constellations were identified between the two parts of the flyway, however, virus gene flow between the northern and southern study locations was evident. Examination of banding records indicate direct migratory waterfowl movements between the two locations within an annual season, providing a mechanism for the inferred viral gene flow. Bayesian phylogenetic analyses provided evidence for virus dissemination from other North American wild birds to AF dabbling ducks (Anatinae), shorebirds (Charidriformes), and poultry (Galliformes). Evidence was found for virus dissemination from shorebirds to gulls (Laridae), and dabbling ducks to shorebirds and poultry. The findings from this study contribute to the understanding of IAV ecology in waterfowl within the AF.

Spruce (Picea abies L.) planting leads post-clearcut bird assemblages to a novel successional pathway\u2014a comparative study in hemiboreal mixed forests

Key messageBird assemblages in planted spruce (Picea abies L.) forests were compositionally distinct from those in naturally regenerated mixed stands. Despite rapid stand development on productive soils, even-aged silviculture cannot host most old-forest species. However, their habitat quality could be supported in landscape mosaics with retention forestry and set-asides.ContextThe most productive forest lands have naturally the richest bird assemblages but tend to be also most intensively managed. Sustainable solutions to this conflict are unclear.AimTo assess bird assemblages and their successional dynamics in planted Norway spruce (Picea abies L.) stands compared to naturally developing stands.MethodsWe mapped breeding bird assemblages in forty 5-ha plots on highly productive soils in Estonia. The plots included sets of naturally regenerated and planted stands, and (as successional endpoints) clear-cuts and old stands.ResultsPlanted stands had fewer bird species and pairs than naturally regenerated stands; the latter having a species composition resembling late-successional deciduous-dominated stands. Importantly, the species composition in mature spruce plantations converged toward the composition observed in late-successional conifer-dominated stands. Downed dead wood, stand age, deciduous trees, and stock density were the most significant stand characteristics shaping bird assemblages.ConclusionThe habitat value of established spruce plantations can be primarily improved by allowing for some deciduous trees and gaps with deciduous undergrowth. At the landscape scale, the bird diversity of even-aged systems would be enhanced by multi-scale applications of retention forestry—from retention trees to old-growth set-asides.

Trumpeter Finch Bucanetes githagineus (M. H. C. Lichtenstein, 1823) in Kazakhstan

The trumpeter finch Bucanetes githagineus (M. H.C. Lichtenstein, 1823) was first recorded for the modern territory of Kazakhstan in 1993. Over the next nearly three decades, these data were slightly replenished, with eight more sightings recorded, most of which belong to the territory of Mangyshlak. Although, in Mangystau, the trumpeter finch has been repeatedly recorded during the nesting period, there have been no reliable facts of its nesting in Kazakhstan until now. The article provides an overview of all the findings of the trumpeter finch for the republic, an annotation for them, as well as a map of the locations of the trumpeter finch both in Kazakhstan and in the territories of neighboring countries. As a result of fieldwork, a new location of the trumpeter finch was registered in the south of the republic: Turkistan Region, the eastern part of the Kyzylkum Desert, the Karatau mountains. Two pairs of birds were recorded. For the first time, a nest of a trumpeter finch was found on the territory of Kazakhstan. The nest was located in a niche of one of the boulders, on a rocky slope of the southeastern exposure of Karamola Mountain. The nest was under construction for a cup. Observations of its construction were carried out. Upon subsequent inspection, the nest turned out to be unfinished and abandoned. The nest was collected and placed in the collection of the Institute of Zoology of the Ministry of Education and Science of the Republic of Kazakhstan. Thus, the first data on the biology of the trumpeter finch in Kazakhstan were obtained.

The nesting ecology of the &lt;i&gt;Corvus orientalis&lt;/i&gt; in Tuva and Buryatia

The ecological features of the eastern black crow Corvus orientalis breeding in the conditions of Tuva and Buryatia are revealed. The species is distinguished by high ecological plasticity, which allows it to inhabit in various natural and anthropogenic landscapes, including settlements of different types. Various types of trees are used for the construction of nests, but conifers are preferred and poplar. They rarely nest on power transmission lines. They nest in single pairs or form small settlements. The black crow is one of the early nesting birds in the region. Nesting begins at the end of March. The main proportion of birds lays eggs before the onset of the phenological summer, starting on April 8-15. Clutches are protected from low temperatures by a warmed nest and incubation from the first egg. The total duration of the nesting period in the region is 100-106 days, as for one pair of birds it is 56-60 days (laying eggs - 5-7 days, incubation - 19-20 days, staying of chicks in the nest - 27-29 days). The nesting period ends by July 20-25. Feeding of chicks coincides in time with the massive appearance of arthropods and, in particular, of Orthoptera, the main objects of their food. The nesting efficiency of the black crow is very high - 93,1%. All these data confirm a wide adaptive potential of the eastern black crow.

Social environment influences termination of nomadic migration.

The final stage of migration, when animals terminate migratory movements and transition to a more sedentary state, remains the least understood phase of migration. Whereas migrants that return to the same locations each year may use mechanisms associated with locating a specific destination, migrants with low site fidelity, such as nomadic migrants, may rely on local environmental cues to determine when to cease migratory movements. Using an experiment with captive birds, we tested whether the presence of a conspecific influences the termination of migration, indicated by changes in behaviour and physiology, in a nomadic migrant (the pine siskin, Spinus pinus). We paired migratory birds with a non-migratory individual or left migratory and non-migratory individuals unpaired. Migratory paired birds had a significant decline in nocturnal activity immediately after pairing and activity levels remained lower two weeks later, with significant declines in energetic reserves and flight muscle size also observed. By contrast, migratory unpaired birds maintained high levels of activity and energetic reserves. These results provide evidence for a role of the social environment in migratory termination decisions. Social cues may be particularly useful in nomadic migrants, such as pine siskins, to facilitate settling in high quality, but unfamiliar, habitats.

Age, Sex and Family Composition of Montezuma Quail (Cyrtonyx montezumae) Coveys in Arizona, New Mexico, and Texas

The Montezuma quail (Cyrtonyx montezumae) is a popular game bird in Arizona and New Mexico, USA, but hunting seasons remain closed in Texas, USA. Estimates of age structure parameters and sex ratios in game birds are essential information for predicting population trajectories and developing sustainable harvest and conservation strategies. Montezuma quail form coveys during the winter as a behavioral strategy for improved survival. In this regard, we harvested 1–4 individuals from 112 Montezuma quail coveys in Arizona, New Mexico, and West Texas from 2009 through 2020 to estimate sex and age composition (juvenile vs. adults) of coveys. We also estimated size for all coveys from which we harvested birds. Mean covey size (± standard error) was 9.7 ± 0.7 individuals (range = 6–12), 9.1 ± 0.5 (range = 2–20), and 5.7 ± 0.7 (range = 2–12) for Arizona, New Mexico, and Texas, respectively although covey size decreased through the winter. The proportion of females among harvested birds was 0.33 ± 0.11, 0.40 ± 0.04, and 0.36 ± 0.33 for Arizona, New Mexico, and Texas, respectively. The proportion of juveniles among harvested birds was 0.83 ± 0.09, 0.71 ± 0.04, and 0.52 ± 0.10 for Arizona, New Mexico, and Texas, respectively. Coveys seem to contain more than one family group (paired birds with current progeny). We estimated that at least 6.2 ± 3.0% and 15.4 ± 10.0% of coveys were mixed families for New Mexico and Texas, respectively, as we harvested more than 2 adult males from the same covey. We did not collect same-sex adults from the same covey in Arizona. Our estimates set apart West Texas in lower average covey size and proportion of juveniles from Arizona and New Mexico at the northern edge of the species’ distribution and may reflect a different population dynamic in the region. However, our estimates must be taken with caution as behavioral response differences between sexes and age categories may differ and may not accurately reflect the actual sex, age, and family composition of Montezuma quail coveys. In addition, results may be confounded by variability in environmental factors over our extended sampling period.