Volume 45 - N. 2
December 2021

Avocetta
Volume 45 - N. 2
Volume 45, Issue 2, December 2021(cover photo by A. Galimberti)



  1. Editorial - Get your hands dirty and expose yourself!

    Corrado Battisti

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  2. Post-fledging habitat selection of a Purple Heron Ardea purpurea revealed by GPS/GSM telemetry

    Michelangelo Morganti, Enrico Viganò, Alessandro Berlusconi, Sara Cioccarelli

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    The Purple Heron is a species of conservation concern in Europe, mainly threatened by the progressive degradation and reduction of wetlands. For future conservation practices, it is of pivotal importance to gather detailed knowledge of its habitat preferences. In June 2018, a nestling of Purple Heron from a sub-Alpine Lake in Northern Italy was equipped with a GPS/GSM device. Habitat selection during the post-fledging period (mid-July to mid-October) was analysed by superimposing the GPS locations to a fine-grained field-based map,
    discerning 14 habitat classes as well as narrow (<2 m) and wide (≥2 m) ditches. The contours of the home range were defined as the 99% kernel calculated on all the gathered locations, which were successively sub selected only retaining 2,017 locations representing the position of the bird every hour and all day long. Within the home range, the habitat availability was estimated by generating 10,000 random distributions of the locations. We firstly verified whether wide ditches were more frequently used by the heron if compared to narrow ones. Eventually, we calculated the ratio between the number of true and random locations falling into the different habitat classes, obtaining a series of class-specific selection ratios. We found a significant preference towards wide ditches compared to narrow ones. Freshly renewed reedbeds and cattail beds were strongly favoured, while high-bearing sedges and Black Alder were also significantly preferred but with lower indices. All the remaining habitats, including mature reedbeds, were significantly avoided. Our results reinforce the indication that the protection of minor landscape elements as ditches and small patches of wet habitats may be of pivotal importance to foster the long-term conservation of bird communities linked to the residual wetlands of the sub-Alpine belt.
  3. The response of bird communities to forest loss in the district Swat Khyber Pakhtunkhwa, Pakistan

    Attah Ullah, Khurshaid Khan, Nehafta Bibi

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    This study examines how avifauna reacts to the loss of forest cover in Swat Khyber Pakhtunkhwa, Pakistan. Birds play a key role in the ecosystem, but in disturbed areas their roles may be limited due to the changes of their natural habitats. We sampled birds in disturbed and undisturbed sites using a fixed radius point counting method. It was revealed that the species richness and abundance of bird species varied significantly between disturbed and undisturbed sites, and that this difference was related to the disturbance indices measured. The results showed that in total, 85 species of birds from 38 families were observed in the 16 sampling sites. Ardeidae (14 species, n = 178) had the greatest abundance and species richness. Twenty of the 85 locally abundant bird species (23.5%) responded significantly to the disturbance regime, resulting in changes in bird species composition. Five vegetation structure variables, including two that were substantially changed by disturbance, were found to be significantly correlated with bird species composition. All changes in bird species composition caused by disturbances are due to changes in vegetation structure. The loss of forest cover, on the other hand, has a negative effect on the diversity of frugivorous and particularly insectivorous species. Our study demonstrated the widespread effect of forest loss on bird communities in one of the most important hotspots for bird conservation and shows that many vulnerable species require extensive forest cover to persist.
  4. Biometric characterization of the Red-legged Partridges Alectoris rufa of northwestern Italy

    Fabrizio Silvano, Pier Giuseppe Meneguz, Paolo Tizzani, Irene Pellegrino, Alessandro Negri, Ennio Negri and Giovanni Boano

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    The biometrics of the Red-legged Partridge Alectoris rufa has been relatively well studied in the western part of its distribution range (Iberian Peninsula and France), especially due to the available large hunting bag samples. Conversely, the Italian population is poorly characterized. We analysed a sample of 254 live birds trapped and ringed in the northern Apennines (province of Alessandria, northwestern Italy), by measuring body mass and the length of wing, eighth primary, tail, tarsus and bill. We found significant differences in some biometric measurements between sex and age classes. A subsample of birds (n = 112) was genetically tested for introgressive hybridization with A. chukar, an introduced species, showing that 16.1 % of free-living partridge are hybrid individuals. When we analysed separately “pure” and “introgressed” birds we found only small biometric differences in body mass of adult males. Finally, our results were compared with the biometry of other populations from the whole natural range of the species (France, Spain and Portugal) showing a negative biometric trend of wing length from westernmost to southeastern birds of the range. Introgressed birds found in the studied population were not easily distinguishable with biometric criteria from pure A. rufa rufa, so genetic analysis is highly recommended when planning reintroductions or restocking.
  5. The effects of egg laying onset, nest size and egg size on the hatching success of the Little Grebe Tachybaptus ruficollis

    Seyed Mehdi Amininasab, Seyed Masoud Hosseini-Moosavi, Mahdi Mardani and Charles C.Y. Xu

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    In 2008, we investigated the relationships between the hatching success of the Little Grebe Tachybaptus ruficollis with egg laying onset, nest diameter, as a proxy of nest size, and egg weight, as a proxy of egg size, in an artificial wetland in Mazandaran Province, northern Iran. The first egg was laid on April 23 and the last chick hatched on July 27. From 118 eggs on 25 nests, we recorded a total of 72 hatchlings (hatching rate: 61%). A generalized linear model (GLM) revealed that while egg size and nest diameter were not significant factors predicting hatching success, egg laying onset predicted significantly the hatching success as early breeders were likely to produce less hatchlings than late breeders. Further studies will be necessary to elucidate the underlying mechanisms of such results.
  6. Short communication - The Alexandrine parakeet Psittacula eupatria as a naturalised breeding species in Italy: a proposal of integration to the national official checklist

    Silvia Giuntini, Leonardo Ancillotto, Emiliano Mori and Andrea Viviano

    Abstract     Read Article       Download
    This short report proposes to integrate the recent checklist of the bird species of Italy with an alien species breeding in Italy since 2011, the Alexandrine parakeet Psittacula eupatria. Two reproductive populations are currently present, one in Reggio Emilia with about 20 individuals and the other one in Rome, with 3-4 birds. Records of single free–ranging individuals of this species of Indian origin occurred in other locations of northern-central Italy, in one case recorded for several consecutive years and then disappeared. If this report
    will be accepted by the COI, the Italian checklist reaches a total of 20 naturalised and not yet naturalised alien birds, i.e. the 3.6% of listed species.
  7. Forum - Searching the effectiveness within conservation projects: Applying the Swiss Cheese Theory to the creation of a supplementary feeding station for the Black Kite Milvus migrans in central Italy

    Jean-Philippe Audinet, Tommaso Baldrati, Patrizia Bonelli, Gino Cecilia, Umberto De Giacomo, Giuseppe Panuccio and Corrado Battisti

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    The paper explores the application of the Swiss Cheese Theory (‘linear accident causation model’) to a local conservation project as a study case: i.e. the construction of a supplementary feeding station to support a local Black Kite Milvus migrans breeding population in a nature reserve of central Italy. In this regard, the project brings light to the conditioning factors (and related ‘slices’) that may be more critical when planning a conservation project. This experience provided valuable lessons in regards to conservation: (i) the authorization process (and related bureaucracy) represented the most challenging obstacle for the promoters and slowed down the project; (ii) the authorization process was easier and faster for a research project that anyway implied providing food to Black Kites; (iii) highly motivated volunteers and expert researchers made the difference; (iv) the use of the ‘effectiveness trajectories’ in conservation projects may highlight critical points, suggesting changes in strategy and facilitating the adaptive improvement of the project.
  8. Bird News - December 2021

    Gaia Bazzi (ed.)

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    This column aims to collect a series of interesting observations and to make it accessible to the scientific community in
    future. We collect observations without time, space or species limitation but we focus on a limited series of category of
    interest. See more on Avocetta website: https://www.avocetta.org/bird-news-column/
  9. Book Reviews - December 2021

    Federico De Pascalis, Roberto Ambrosini, Michelangelo Morganti

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    The following book shave been considered in this issue of Avocetta: 
    Stroud D.A., Cromie R., Finlayson M. et al 2021. International treaties in nature conservation: a UK perspective. Biodiversity Press. 94 p. 
    Harrison P., Perrow M. & Larsson H., 2021. Seabirds. The New Identification Guide. Lynx Edicions. 600 p.
    Panuccio M., Mellone U. & Agostini N., 2021. Migration Strategies of Birds of Prey in Western Palearctic. CRC Press, Boca Raton, Florida, USA.