Ballardini Marco

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  • Working Paper
    Photoidentification catalog of Cuvier's beaked whale (Ziphius cavirostris) in the Ligurian Sea
    (Woods Hole Oceanographic Institution. Contact: Alessandro Bocconcelli,, 2008-04-08T19:56:48Z) Revelli, Eletta ; Pusser, Todd ; Bocconcelli, Alessandro ; Ballardini, Marco ; Sturlese, Albert ; Johnson, Mark P.
    A photo-ID catalog of Cuvier's beaked whales was compiled by analyzing data collected in the Ligurian Sea from 1998 to 2007. Data were collected during dedicated surveys for beaked whales, opportunistic whale watching cruises, and during several tagging efforts. A total of 2,300 photographs was collected and referenced to time and GPS position. Of these photographs, 650 were of sufficient quality to use for photo-identification. Photographs were divided into four categories, based on scarring and pigmentation patterns: very distinctive (heavily scarred and/or bold pigmentation), distinctive (many distinct scars and/or bold pigmentation), slightly distinctive (few scars and lack of bold pigmentation), and not distinctive (no scars and solid brown animal). 127 individual whales were identified, of which 10 were classified as adult males, 3 as adult females, 3 as calves, and 27 as immature whales, based on the above criteria. An additional 26 whales were classified as possible males, and 28 as possible females. During the 9 year study period, 34 whales were resighted, and the longest time between resights was 7 years.
  • Article
    Immigration as the main driver of population dynamics in a cryptic cetacean
    (Wiley Open Access, 2023-02-11) Tenan, Simone ; Moulins, Aurelie ; Tepsich, Paola ; Bocconcelli, Alessandro ; Verga, Alessandro ; Ballardini, Marco ; Nani, Barbara ; Papi, Daniela ; Motta, Gabriella ; Aguilar, Ana Sanz ; Rosso, Massimiliano
    Empirical evidence about the role and interaction of immigration with local demographic processes in shaping population dynamics is still scarce. This knowledge gap limits our capability to derive a conceptual framework that can be used to inform conservation actions. Populations exposed to nonstationary environment do not converge to a stable stage distribution, implying the need for evaluating the demographic role of both vital rates and stage distribution using appropriate tools. This is particularly important for species with larger generation times like cetaceans. We explored the relative demographic role of vital rates and population structure of a poorly known cetacean, the Mediterranean Cuvier's beaked whale, while accounting for the exposure to nonstationary environments. We performed a retrospective analysis through transient life table response experiments (tLTRE) using demographic rates and population structure of both sexes obtained from an integrated population model. The contribution of immigration to variation in realized population growth rates was 4.2, 7.6, and 12.7 times larger than that of female apparent survival, proportional abundance of breeding females with a 2-year-old calf, and proportional abundance of breeding females with a 3-year-old calf, respectively. Immigration rate and proportional abundance of breeding females with a 2- or 3-year-old calf explained, respectively, 65% and 20% of total temporal variability in realized population growth rates. Changes in realized population growth rate between successive years were mainly driven by changes in immigration and population structure, specifically the proportional abundance of breeding females with a 2-year-old calf. Our study provides insight into the demographic processes that affect population dynamics and in a cryptic cetacean. We presented an analytical approach for maximizing the use of available data through the integration of multiple sources of information for individuals of different distinctiveness levels.