Neotropical seasonally dry forests (NSDF) are widely distributed across Latin America and the Caribbean. They possess important levels of species richness and endemism but few studies have assessed the diversity patterns and ecological relationships between the entire avifauna of these threatened forests. Thus, in order to analyse the macro-ecological patterns and the community structure of NSDF avifaunas, we generated species distribution models describing the current geographical distribution of 1,298 bird species inhabiting NSDF. We assessed species richness gradients in terms of distance from the Equator using both linear and polynomial regressions. Then, based on a matrix composed of the presence or absence of species in 563 quadrants, we performed cluster analyses (considering the Simpson dissimilarity index [β_SIM] as a distance measure) to identify the main NSDF regions and describe the avifaunal affinities among them. For the identified groups, we estimated the dissimilarity values, using both an ANOSIM test and the β_SIM index. Overall, we observed the lack of an equatorial peak for species diversity of NSDF avifauna in the latitudinal gradient and identified 12 avifaunistic groups. The β_SIM index among the NSDF avifaunal groups ranged from 0.05-0.73, showing statistically significant differences (R = 0.894, p = 0.001) in species composition among them. Species shared between two or three NSDF groups comprised a higher proportion (∼38%) than those exclusive to each group (∼23%). Only 35 species were shared between the 12 groups. This information supports a separation of the NSDF avifauna into two major groups (northern and southern), as well as the idea of connections during recent geological time among the NSDF in southeastern South America (the so-called Pleistocene Arc Hypothesis). We provide a scientific framework to contextualise the importance of each NSDF nuclei in terms of their avifauna, supplying an ecological basis for future conservation decisions in order to protect their diversity. —Prieto-Torres, D.A., Rojas-Soto, O.R., Santiago-Alarcón, D., Bonaccorso, E. & Navarro-Sigüenza, A.G. (2019). Diversity, endemism, species turnover and relationships among avifauna of neotropical seasonally dry forests. Ardeola, 66: 257-277.

Many studies have focused on the colonial behaviour of birds but information on the processes related to the addition of new breeders to colonies is still scarce. The breeding parameters of new, young, breeders in a colony differ from those of experienced breeders initially. Hence, there must be an underlying process to synchronise such parameters of the new additions to the original colony values. To determine how this synchronisation process takes place, we surveyed a White Stork colony in the northern Madrid province (Spain) for five consecutive breeding seasons. Given the high nest site fidelity of this species, we established a relationship between nest age (new or old) and breeding pair age (young breeder or established adult). Newcomers occupy new nests whereas established breeders use old nests. We compared the laying dates at new nests over a 3-4 year period with those at the old nests in the colony to determine whether new breeding pairs were synchronising their laying dates to those of the existing colony. Young breeders require up to three breeding seasons to synchronise their laying dates with those of the established colony. To our knowledge, this is the first time that such a synchronisation process has been described for storks. Nest age should also be considered when analysing breeding parameters that may differ between young and old breeders. —Cabodevilla, X. & Aguirre, J.I. (2019). The nesting synchronisation process of new breeders in a White Stork Ciconia ciconia colony. Ardeola, 66: 279-289.

The distribution of resident and migratory bird abundance across mangrove and marsh patches can produce dynamic and guild-specific habitat-use patterns. Using 32 consecutive months of point counts in a coastal landscape in Oaxaca, Mexico, we studied the annual cycle, non-breeding season (October to March) and breeding season (May to August) of terrestrial birds. For broad trophic guilds of plant-consumers and insectivores, we disclosed seasonal dynamics and assessed the spread of non-breeding season abundance across migratory habit categories and habitat types. To test for habitat-use patterns derived from hypotheses concerning specific trophic resources, we focused on subsets within trophic guilds: frugivores (plant-consumers that mainly eat fruit) and invertebrate gleaners (insectivores that mainly eat terrestrial leaf and stem invertebrates). Drawing on a resourcecentred dietary requirement hypothesis, we predicted lower abundance of migrant frugivores in mangrove, where palatable fruit availability was expected to be low and resident frugivores probably exploited invertebrates to feed nestlings. Based on the competition-oriented nest predation hypothesis, we anticipated a higher proportion of migrant invertebrate gleaners in marsh. We recorded migrant birds in every month of the year. For 20 plant-consumer species, the non-breeding season density was highest among residents in mangrove (> 5 individuals per hectare). For 46 insectivore species, densities were > 5 and > 9 individuals per hectare for migrants and residents, respectively. Comparable average abundances in trophic guilds suggested both migrant and resident species were equally important. For 14 frugivore species, a higher proportion of migrants in marsh (0.90) than mangrove (0.03) resulted from reciprocal between-habitat changes in migrant and resident abundances, as predicted by the dietary requirement hypothesis. For 22 invertebrate gleaners, proportions of migrants in mangrove (0.45) and marsh (0.55) were comparable, as were abundances. Contrary to the nest predation hypothesis, any between-habitat variation in invertebrate gleaner nesting activity did not markedly influence non-breeding season abundance. —Ruiz, M.D.M., León-Cortés, J.L., Enríquez, P.L., García-Estrada, C. & Rangel Salazar, J.L. (2019). Habitat-use patterns among migrant and resident landbirds of contrasting dietary habits in a southern Mexican wetland. Ardeola, 66: 291-310.

Audio recording systems coupled with automated song recognition are commonly being used for monitoring wildlife. Recorders usually differ in cost and effectiveness, and their performance may vary with source distance, wind speed and acoustic source direction, among other factors. We here assess the cost-effectiveness of five audio systems considering such factors as distance and singing direction. We developed field tests using playback of Dupont's Lark Chersophilus duponti songs from nine fixed locations at distances of 1 to 256m, played towards or away from the recorders' position. We selected this species because its very characteristic song should be easily identified by automated signal recognition software. Field tests were carried out during March 2016 in level dwarf-shrub steppe (mean height < 40cm) in NE Spain. We found large differences in effectiveness between recorders. The number of songs detected by an automated signal recognition algorithm significantly decreased with distance and when playback was angled away from the recorder position, a factor never previously tested. Finally, we give the design of a cost-effective Autonomous Recording Unit, based upon the most effective recorder. We recommend researchers working with acoustic recorders to evaluate the performance of several devices before making a selection for long-term monitoring programmes, and to consider such factors such as singing direction in their analyses. —pérez-Granados, C., Bota, G., Giralt, D., Albarracín, J. & Traba, J. (2019). Cost-effectiveness assessment of five audio recording systems for wildlife monitoring: differences between recording distances and singing direction. Ardeola, 66: 311-325.

Urbanisation poses important challenges for animal communication. Avian dawn choruses are a prominent component of urban soundscapes and have received attention in recent urban ecology studies. Current evidence based on comparisons of urban and non-urban sites suggest that urbanisation is associated with earlier dawn chorus singing activity. However, this phenomenon remains mainly unexplored in tropical cities. We here assessed dawn chorus onset and peak times in two contrasting conditions of the urbanisation intensity gradient (i.e., intra-urban and peri-urban forested areas) of a Neotropical city, Xalapa in Mexico, assessing relationships with noise at sunrise and artificial light at night. We found no differences in dawn chorus onset or singing peak times when contrasting intra- and peri-urban areas. However, we found non-significant trends for earlier chorus onsets and peak times with increasing noise levels. Our results show no relationship between artificial light at night and dawn chorus timing, adding evidence to recent studies showing that light pollution does not seem to be determinant in the dawn choruses of tropical birds. Further research is needed to include a wider array of urbanisation conditions and drivers of the singing routines of urban tropical birds. —Marín-Gómez, O.H. & MacGregor-Fors, I. (2019). How early do birds start chirping? Dawn chorus onset and peak times in a Neotropical city. Ardeola, 66: 327-341.

The relative abundance of the Azorean Buzzard Buteo buteo rothschildi, both temporally and spatially, was assessed to determine its land use preferences and to support its conservation. The main aims were to compare its relative abundance between years, islands and localities and to relate these to land use in the context of habitat changes. Randomly selected plots were surveyed using two sampling methods: strip transect and point counts, to record any buzzards seen during the breeding season and to assess land use characteristics. The buzzards were most numerous on the largest island (São Miguel), and least numerous on the smallest one (Graciosa), as expected. However, we did not find significant differences in abundance among localities in Graciosa or between years in both islands. We only found local variation in abundance on S. Miguel. The overall population stability clearly favours the conservation of this Azorean endemic subspecies. Finally, we found that buzzards avoid industrial areas, urbanisation, natural vegetation and agricultural land, a finding that should be kept in mind by policymakers. These results may be used for landscape planning and management by authorities. There are several regional Management Plans with a spatial dimension but for land use classification the Municipal Master Plans have the discretionary power to classify urban and rural areas. Therefore, this information should be integrated into the decision process of the local classification actions. Future studies should include further habitat variables to assess their relationships with buzzard abundance, but also to extend the analyses to the remaining Azorean Islands in order to understand more deeply how this insular raptor responds to habitat changes. The results of these studies should strengthen law enforcement on land use sustainability and help to promote awareness among managers, landowners, stakeholders and the general public. —Lopes, M., Pereira, D.G., Afonso, A. and Melo, F. (2019). Relative abundance of the Azorean Buzzard Buteo buteo rothschildi and its responses to land use. Ardeola, 66: 343-360.

The Black-headed Gull Larus ridibundus, like many other gulls, has monomorphic plumage, which impedes sex identification in the field. We analysed the size of the hood, eye ring and wing tip and found that putative ornaments did not differ between sexes in this species. We formulated a novel discriminant function for Black-headed Gulls using morphometric measurements of live individuals (i.e. total head length, bill depth, and the sixth rectrix length), intentionally excluding data from dead birds, which were on average significantly smaller than their living conspecifics. We also tested cross-application of discriminant functions previously developed for Black-headed Gulls, proving that sexing individuals from different populations, even geographic neighbours, based on a single discriminant function risks errors and showing that discriminant functions cannot be treated as a universal tool for sex identification across space and time. —Indykiewicz, P., Minias, P., Kowalski, J. & Podlaszczuk, P. (2019). Shortcomings of discriminant functions: a case study of sex identification in the Black-headed Gull. Ardeola, 66: 361-372.

En este informe se ofrece información sobre 126 especies que se reparten por toda la geografía nacional. Se hace especial esfuerzo en 35 especies escasas o que se presentaron de forma puntual en el año 2018, para las que se muestra su distribución espacio-temporal mediantes mapas y gráficas que recogen el número de citas que proporcionan información sobre su patrón de presencia (véanse Molina et al., 2017, 2018 y 2019). Algunos casos corresponden a especies retiradas de la lista de aves raras recientemente (véanse Rouco et al., 2018; Gil-Velasco et al., 2018, Gutiérrez, 2019; Reservoir Birds, 2019). Se actualiza la secuencia taxonómica de acuerdo con la nueva lista patrón de las Aves de España (Rouco et al., 2019).