An Analysis of Orientation Cage Field Data – A Case Study of Headings of the Blackcap, Sylvia atricapilla, at the Bukowo/Kopań Ringing Site in Poland

One of the most effective methods of studying the migratory patterns of nocturnal passerine migrants is the use of orientation cages as a supplementary procedure at ringing sites. The most comprehensive studies using orientation cages (Busse’s Flat Orientation Cage) were conducted within the SEEN network (SE European Bird Migration Network), with more than 43,000 tests performed at more than 40 ringing sites in autumn. A number of papers were published based on these data, presenting an overall pattern of passerine migration over SE Europe-Middle East-NE Africa. For more detailed analyses, it was first necessary to solve some methodical problems within case studies. The current work presents details for discussion based on data from 1338 tests of Blackcaps performed during the years 1995–2010 at a single ringing station, Bukowo/Kopań, located on the Polish Baltic coast. The birds were tested according to the standard methodology of the SEEN network (Busse 2000). The problems investigated were (1) the repeatability of heading patterns obtained in different years, (2) the linearity of the estimated arrival and departure headings, and (3) quantitative aspects of the results in the description of the heading pattern when migratory groups are found.It was determined that (1) yearly heading patterns were generally coherent and could be analysed as uniform case data; (2-1) the hypothesis that the arrival/departure heading axes are generally linear is accurate to within about one 10° sector, at least in the case of the Blackcap. This is coherent with impressions from other known data sets, but does not mean that the rule always applies to all species at every location on the migration route. In the future, this problem should be studied on a more detailed scale. It was further established that (2-2) estimating arrival and departure headings makes it possible to define migratory groups (populations) passing the study site. The direct heading estimation procedure seems to be more sensitive in identifying migratory groups than the calculation procedure. Moreover, (3-1) the calculation procedure makes it possible to estimate some quantitative properties of headings of migratory groups and define some interesting, though preliminary, number patterns of local migratory patterns; (3-2) the number relations between birds demonstrating the arrival and departure headings of the migratory group seem to be an interesting parameter for study on the distance of migration of groups within a species and, possibly, between species. This is another interesting problem that cage tests could be used to solve in the future. Finally, (3-3) knowledge about trends of individual populations passing the defined site becomes accessible only using analysis of data from orientation cages. The estimated quantitative indices discussed above could be helpful in presenting the general migratory pattern of the species on a geographical scale.

The Autumn Migration of the Citrine Wagtail, Motacilla Citreola, in the Lviv Region (W. Ukraine) During its Range Expansion

The Citrine Wagtail has been gradually expanding its breeding range from Asia westward into Europe since the middle of the last century. New breeding records of this species further to the west of Europe have emerged during the last several decades. The distribution of the Citrine Wagtail in Western Ukraine began at the end of the last century. A total of 48 Citrine Wagtails were ringed in August 1995–2016 at the Cholgynskyy ornithological reserve (West-Ukrainian Ornithological Station). The birds were recorded mainly in the first half of August, peaking from the beginning of the second decade to the middle of the month. At the beginning of August there were wagtails in different stages of moult. Adult moulted birds were recorded from the beginning of the second decade of August, while juvenile birds underwent partial moult during the first part of the month. The mean weight of adult moulted birds was higher than that of juveniles. At the beginning of August many Citrine Wagtails were lean, without fat reserves, with the mean fat class increasing by the end of the month. The autumn passage of M. citreola took place in W. Ukraine. Birds stay in the shallow waters, pastures, and reed beds to feed, overnight, moult and gain fat reserves for migration.

The Role of a Water Canal and Secondary Forest for Migrants

Forests have an important role during migration. They act as ecological corridors and provide resting and feeding places for birds. In our study, we sought to determine whether migratory birds prefer secondary forest or canal vegetation during migration. The study was carried out in Southeast Hungary, in an oleaster forest and in a canal. We used 12 mist nets and the ringing method. The study period lasted from August to October 2016–2018, covering approximately the entire migration period. According to our results, the canal has a significant effect on the species assemblage, as it functions as a migration corridor during migration, most likely not only for diurnal migrants, but for nocturnal migrants as well. Our results showed that the presence of both woody and berry plants had some influence on the species composition. Interestingly, the presence of berries had a positive effect on the presence of insectivorous birds.

Community Structure of Migratory Waterbirds at Two Important Wintering Sites in a Sub-Himalayan Forest Tract in West Bengal, India

The waterbird community structures of two sub-Himalayan wetlands (Nararthali and Rasomati) situated in forested areas were compared during the wintering period. These wetlands had similar geophysical features but were subject to different conservation efforts. Sixty species of waterbirds, including four globally threatened species, were recorded during the study. Nararthali was found to be more densely inhabited (116.05±22.69 ind./ha) by birds than Rasomati (76.55±26.47 ind./ha). Density increased by 44.6% at Nararthali and by 59% at Rasomati over the years of the study, from 2008 to 2015. Winter visitors increased considerably at Nararthali (66.2%), while a 71.1% decrease at Rasomati clearly indicated degradation of habitat quality at that site during the later years. Luxuriant growth of Eichhornia crassipes, siltation, poor maintenance and unregulated tourist activities were the key factors leading to the rapid degradation of Rasomati. Nararthali, on the other hand, a well-managed wetland habitat, showed an increasing trend in bird densities. Therefore, poor habitat management and rapid habitat alterations were observed to be the main reasons for depletion of bird density in the wetlands of eastern sub-Himalayan forest regions.

Autumn Migration of the Wood Pigeon, Columba palumbus, at Eastern Part of the Polish Baltic Coast

The Wood Pigeon, Columba palumbus, is a common diurnal migrant across most of the Europe. The visual observations were carried out during autumn work of the Operation Baltic ringing stations, mainly at Mierzeja Wiślana (54°21’N, 19°19’E) parallely to the ringing of birds. Observations of passing birds were performed 15 minutes per every hour from sunrise to sunset. The autumn observation period was long enough to cover whole pigeons migration at the southern coast of Baltic (14 Aug. – 11 Nov.). Altogether 119,019 Wood Pigeons were observed within 20 seasons of observations. The goals of this work is (1) to describe the course of the Wood Pigeon autumn migration at the Polish Baltic coast as to numbers in long-term aspect and the seasonality of migration, (2) to propose further development in the study on wave structure of the bird passage. The main analysis of this work-description of the seasonal dynamics of migration - was carried out with modified and widened method used for that kind of analysis in earlier publications. In the present paper the wave structure is described by the estimated border days between supposed waves taking under consideration different properties of the passage dynamics. Here are used three groups of parameters: (1) total numbers of birds observed daily during several years, inter-year variability (as SD between year number values), and the coefficient of variation (V), (2) number of migration peaks that occurred in that date within years of the study (there were used two classes of peaks – High Peaks and Peaks), (3) numbers of birds passing during recognized peak days. All estimations were done independently of others and only finally summarized using common ranking scheme. Such step by step procedure make estimation more and more reliable. Very high agreement between estimations based on three groups of parameters suggests strongly that the proposed estimation procedure is effective enough.

A New Approach to Assessment of Bird Carcass Removal (Scavenging) Time on Wind Farm in Egypt

Wind farms developing rapidly in order to meet the high demand for energy from green sources. However, the impact of wind farm operation on the environment still needs to be established. The risk to wild birds is drawing the attention of stakeholders and bird conservation organizations. Carcass search is the main method used to assess the impact of wind farm operation on wild birds of various systematic groups and sizes. Assessment of the overall risk that wind farms pose to birds depends primarily on accurate calculation of carcass removal times and the detection ability of the searcher. Most studies have assessed the carcass removal time using pet bird species, pigeons, or various local birds. In Egypt, all studies conducted in operating wind farms up to 2016 had used chickens to assess the carcass removal time and in this way to the estimate the total number of bird fatalities within wind farms. The use of birds killed by a wind farm in carcass removal trials provides the actual time of carcass disappearance, in contrast with the use of other bird species. The removal times of carcasses of parakeets, quails, partridges and chickens were shorter than those of carcasses of White Stork, White Pelican, Honey Buzzard, Black Kites and eagles used in the current study and in another study in Australia. The results of the present study indicate that carcasses of birds killed within the studied wind farm remain for two to three months, while the carcasses of other in species other localities remain no more than 1 to 15 days, which unquestionably influences the calculation of total fatalities and leads to overestimation of the overall risk that wind farms for birds.

Orientation of Trans-Saharan Passerine Migrants in Southwestern Spain – Revisited

At the end of the 1980s, a relatively large data set was collected from orientation cage tests of nocturnal migrants caught in one locality in south-western Spain. It was published in The Auk in 1989. At the time of publication, the use of orientation cages was a major advance in detailed studies on passerine migration patterns. The basic evaluation procedure was to calculate the average vector of all numbers representing bird activity in a number of sectors of the full wind-rose and to use the Rayleigh test to determine the statistical significance of the distribution. However, due to hidden assumptions in the procedure used at that time, the resulting heading patterns could be called into question in light of further methodological development. The paper revisits the original set of orientation data collected in the last century in the reported study. The new results from the multimodal distribution accepting procedure are compared with the older pictures and are found to be much better at explaining the migration pattern there. In particular, the Garden Warbler and Reed Warbler, which were claimed to be ‘disoriented’, now show acceptable directionality patterns which do not differ in shape from those of other species.

Estimation of the Autumn Migration Pattern of Passerines within the SE European Flyway by Orientation Cage Tests

The general migration pattern of passerines can be estimated using a variety of methods. A number of partial analyses based on ringing data, usually limited to a few species, have been published. A very few continent-scale presentations have been offered, as extremely long periods of ringing activity are necessary for passerines. This is especially true for areas where the recovery rate is very low, including vast areas of north-eastern and eastern Europe and the Middle East/Africa. Similarly, radar and moon-watching studies are of limited value for drawing migration patterns within wider areas. Radar studies require good coverage by the radar systems, while weather radar distribution density and the level of evaluation are very uneven. Modern logger and satellite tracking are more applicable to non-passerines, and as yet enable detailed study only of limited numbers of individuals, and not population studies. At the end of the 20th century, a very simple tool was introduced for field studies on the preferred headings of individual birds caught for ringing, i.e. the use of flat orientation cages. This method was introduced as a standard within the SEEN (SE European Bird Migration Network) in 1995. This study presents a preliminary large-scale evaluation of the data collected within this project. The database used contains more than 43,000 orientation tests performed at 45 ringing sites. The area covered stretches from the northern part of western Russia to southern Egypt and from Italy and Poland to Siberia and Armenia. Eight streams of migration are identified within this area, creating a fairly complicated pattern of avian movements.

Effect of Multiple Adjoining Habitats on Avifaunal Diversity in an Agriculture-Based Wetland Adjacent to the Hooghly River, West Bengal, India

Sau M., Chakraborty M., Das R. and Mukherjee S. 2018. Effect of multiple adjoining habitats on avifaunal diversity in an agriculture based-wetland adjacent to the Hooghly River, West Bengal, India. Ring 40: 59-92. This study was conducted on four plots having a cluster of different combinations of forest, wetland, and agricultural land, as well as a single marshland habitat near the river Hooghly. We obtained 17,817 counts for 150 species in 32 days of year-round sampling. The wetland-agricultural land associated with forest had the highest species diversity (132 species, Shannon ̄H – 1.63), heterogeneity (Shannon J’ – 0.773), and number of unique species (33 species), and the lowest dominance (Simpson Index 1/D – 39.35), in contrast with the marsh, which had the lowest diversity (41 species, Shannon ̄H – 1.39), highest homogeneity (Shannon J’ – 0.863), and a lack of uniqueness. The plot with secondary forest patches between an agricultural field and human settlements showed the highest species dominance (Simpsons Diversity 1/D – 17.465). Species rarity ranged from 68.2% to 77.6% within the area under study. There were 25 species common to all plots, which formed six distinct groups based on their abundance. Carnivores were found to be the dominant foraging guild throughout the habitats. Thirty-two per cent of the species are migratory, with the families Scolopacidae and Motacillidae predominating. The Jaccard and Sorensen indices reveal the greatest species similarity between the wetlandpisciculture plot and the marshland. These indices together with the hierarchical cluster analysis indicate the uniqueness of the plot of open forest habitat adjoining the wetland, which offers the best living conditions for migratory species. Our study concludes that when a wetland is surrounded by agriculture rather than fisheries, avifaunal diversity increases, whereas forest-associated wetland-farmland maximizes species richness with minimum dominance and hence imparts greater stability to the overall community structure.

The General Pattern of Seasonal Dynamics of The Autumn Migration of The Wood Pigeon Columba Palumbus in Italy

Cavina E., Bucchi R. and Busse P. 2018. The general pattern of seasonal dynamics of the autumn migration of the Wood Pigeon Columba palumbus in Italy. Ring 40: 3-18. Given the scarcity of studies on the migration of the Wood Pigeon through Italy, the first systematic observations by a network of hunters, as citizen researchers, can be presented as a starting point for more in-depth analyses. Observations from the years 1998-2006 are analysed and presented in a generalized form. During this period more than 100 observation sites, covering most of Italy, were active for about 40 days every autumn. Migration over Italy was described in terms of the timing and intensity of migration. Special attention was directed to the long-term number dynamics and seasonal dynamics of the passage. The most intensive migration was observed within northern Italy, while lower intensity is visible more to the south of the peninsula. Following tendencies in numbers of observed migrants within the ten years of the study, we can find positive tendencies in most of the northern provinces, while three negative trends are visible in central Italy. The study of the seasonal pattern, in terms of the number dynamics of the passage and the frequency of pronounced peak days, strongly suggests that there are five or six waves of pigeons passing through Italy in different parts of the autumn that are quite stable between years. Every year the time of the passage includes a few peak days of migration.