Volume 19 - N. 2
December 1995

Volume 19 - N. 2

  1. Residui di mercurio, piombo, cadmio e cromonelle uova di cinque specie di uccelli nidificanti in Lombardia


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    55 451

    Nella primavera 1990 sono state raccolte e analizzate 95 uova di 5 specie di uccelli nidificanti in
    Lombardia allo scopo di identificare e quantificare la presenza dei metalli mercurio, piombo, cadmio, cromo
    in esse. Le specie erano: Germano reale Anas platyrhynchos, Merlo Turdus merula, Gallinella d’acqua Gallinula
    chloropus, Cornacchia grigia Corvus corone cornix, Piccione domestico Columba livia domestica. Sono
    state rilevate le dimensioni delle uova, è stato calcolato l’indice guscio e il volume e ne sono state ricercate le
    correlazioni con le concentrazioni dei quattro metalli. Solo per due specie i coefficienti di correlazione sono
    risultati significativi: per la Cornacchia grigia tra il mercurio e indice guscio (P

  2. The population of Bittern Botaurus stellaris  in the Diaccia Botrona marsh, Central ltaly: four years of census (1991-94)


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    16 71

    The Bittern population of a marshland in Centralltaly was censused using a network of listening
    stations. This technique appears to be sufficient to quantify the population being examined, but does not
    allow an accurate analysis ofthe positions ofthe boorning males.
    The data in the literature, dating from 1974, indicate that the population studied had a progressive increase
    up to the early 1990s (from O-l to 14-18 males) and then a phase of decline (with 7-9 in 1994). These
    variations seem mainly due to the changes in the marsh vegetation. This was positive at first, thinning out
    the reedbeds, then negative with their progressive reduction.
    However, the role ofprimary irnportance ofthe studi ed population in ltaly has been confirmed.

  3. Impact of human activity on foraging flocks and populations of the alpine chough Pyrrhocorax graculus


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    21 45

    The Alpine Chough Pyrrhocorax graculus is a social corvid which uses food provided by tourist
    activities in mountain regions (e.g. at ski stations, refuse dumps, picnic areas). In order to determine the
    impact ofthe human food supply on the Alpine Chough, foraging flock size and distribution were studied in
    a tourist region in the Northern French Alps between 1988 and 1992. Alpine Chough attendance at tourist
    sites was closely related to human activities. Activity rhytbrn was influenced by human presence on picnic
    area in summer. Relations to human activities held at a seasonal scale (such as opening of a ski station) but
    not at a daily time scale (such as weekend). Long term trends of Alpine Chough populations since intense
    tourist development at altitude are discussed with regard of flock size counts recorded at a same site before
    and after intense tourist development.

  4. Nest site selection by Cormorants Phalacrocorax carbo at the colony of Val Campotto, NE Italy

    Grieco F.

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    15 52

    The phenology and structure ofthe nest-sites of a Connorant colony in dead trees, during 1992-
    1993, are described. Sites were c1assified using three criteria: (I) topography ofthe colony; (2) density of
    breeding trees; (3) structure ofbreeding trees. Photographs were used to mark the nests during the breeding
    periodo The number ofnests increased to a peak in early May and then declined; many nest sites were used
    successfully by more than one pair. The structure of nest sites was more important than their position. The
    percentage of sites reaching the nest stage decreased during the breeding season. Adult birds showing much
    white on the head are more frequent in the centre ofthe colony. Sites taken by breeding immature-plumaged
    birds are like those taken by adults, but immatures seem to succeed in building nests and breeding only on
    sites of lower quality. Beginning from 1992 some breeding attempts occurred on sites outside the present
    colony. Current level of competition between Cormorants and Grey Herons which breed in the same area is
    low. Differences between this and a similar German colony are discussed.

  5. Causes and consequences of egg size variation in Swallows Hirundo rustica

    WARD S.

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    19 57

    Relationships between egg mass, egg composition, hatchling mass, female characteristics and
    environmental conditions during egg formation were investigated for Swallows Hirundo rustica in CentraI
    Scotland. Egg dimensions were highly correlated with egg masso 60% of variation in egg mass originated
    from differences between females. Egg mass was repeatable (repeatability=0.54) for individuaI birds but
    was not related to other female characteristics such as measures of structural size. Egg mass was not related
    to clutch size, hatchability or position in the clutch. Eggs contained more lipid iffavourable environmental
    conditions prevailed during egg formation. Heavier eggs contained more lipid and lean dry component. A
    sample of eggs was hatched in a incubator so that hatchlings could be matched with the eggs from which
    they emerged. Egg mass explained 60% ofvariation in hatchling masso 79% ofvariation in hatchling mass
    was explained by the first component in a principal component analysis which used egg mass, length and
    breadth to describe egg size. Heavier eggs produce larger hatchlings which generally grow faster and have
    greater survival across 34 studies of non-passerine birds. Although larger passerine eggs produce hatchlings
    which are initially larger and grow faster (n=7 studies) this does not lead to increased survival. Hirundines
    lay relatively small eggs for their body size although production oflarger eggs was predicted to have little
    extra cost for a Swallow and should be advantageous as larger hatchlings would be more likely to survive
    periods of food shortage.

  6. Off-nest behaviourof the Little Tern  Sterna albifrons during incubation


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    19 58

    The off-nest behaviour of the Little Tem Sterna albifrons was studied in the Axios Delta, a
    Macedonian wetland. The time taken up by the following components of this behaviour was measured
    during incubation in four nests and during different parts of the day: Away from nest, Shift during
    incubation, Chase of intruders, Throwing Sideways, Around nest, Wake Up and fly, Courtship Feeding and
    Human Disturbance. Data were analysed by Repeated-Measures ANOV A. There were significant effects of
    nest, day and part ofthe day on a number ofthese components of off-nest behaviour. The birds from one of
    the nests spent very different proportions of time on the various activities than those at the other nests. The
    effects ofthe part ofthe day were clear and some activities exhibited trends: time spent on Away and Shift
    typically decreased from the beginning to the end ofthe day, Human Disturbance was diminished in the third
    part ofthe day and Wake Up and Throwing Sideways were greater in the middle ofthe day. Despite clear
    day effects on many variables there was no regular pattem to these. There was also an interaction of day and
    part of the day on Away, Throwing Sideways, Human Disturbance and Wake Up denoting that these
    activities were affected by unpredictable events.

  7. The use of feather length as a method formeasuring the wing shape of passerines


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    15 187

    The method normally used to measure the wing shape in both live birds and museum skins, is
    based on the measurement of the distance between the tip of each primary and the tip of the folded wing.
    This method has two essential shortcomings: it does not allow to compare live birds with museum skins and
    it is difficult to standardise when different observers are involved. It seems therefore inadeguate for studying
    the wing shape variation ofpopulations breeding on a large geographical range. Here we propose to use the
    total feather length for measuring the wing shape. This will allow to compare living birds with museum skins
    and to obtain comparable results from different ringers.

  8. Accuratezza di due diversi metodi per la misurazionedella lunghezza dell'ala utilizzati da operatori inesperti


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    15 47
  9. A short-term defence of fruit-bearing plants by the blackcap (Sylvia atricapilla)

    Pandolfi M.

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    15 54
  10. Scavenging feeding by wintering Great Cormorants Phalacrocorax carbo sinensis


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    16 101
  11. The Grey Heron in CentraI Liguria


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    16 47
  12. Nuovi avvistamenti

    Arcamone E. & Brichetti P.

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    31 109
  13. Book Reviews

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    20 44