Exploratory analyses ofmigration timing andmorphometrics of the Common Blackbird (Turdus merula)

Abstract

Ornithological studies often rely on long-term bird ringing data sets as sources of information. However, basic descriptive statistics of raw data are rarely provided. In order to fill this gap, here we present the fourth item of a series of exploratory analyses of migration timing and body size measurements of the most frequent Passerine species at a ringing station located in Central Hungary (1984-2016). First, we give a concise description of foreign ring recoveries of the Common Blackbird in relation to Hungary. We then shift focus to data of 6849 ringed individuals and 6081 recaptures derived from the ringing station, where birds have been trapped, handled and ringed with standardized methodology since 1984. Timing is described through annual and daily capture and recapture frequencies and their descriptive statistics. We show annual mean arrival dates within the study period and present the cumulative distributions of first captures with stopover durations. We present the distributions of wing, third primary, tail length and body mass, and the annual means of these variables. Furthermore, we show the distributions of individual fat and muscle scores, and the distributions of body mass within each fat score category. We distinguish the spring and autumn migratory periods, breeding and wintering seasons, ages (i.e. juveniles and adults) and the two sexes. Our aim is to provide a comprehensive overview of the analysed variables. However, we do not aim to interpret the obtained results, merely to draw attention to interesting patterns that may be worth exploring in detail. Data used here are available upon request for further analyses.

Altitudinal movements of four montane passerines in Hungary

“…A good example of age-and sex-specific differences is the Pygmy Owl (Glaucidium passerinum Linnaeus, 1758), where the proportion of juveniles and females leaving the nesting sites is much higher than that of adults and males (Polakowski et al 2008, Lehikoinen et al 2011. A similar pattern in Passerines can be observed in Common Blackbirds (Turdus merula Linnaeus, 1758) (Csörgő & Kiss 1986, Ludvig et al 1991.…”

Biometric data of North African Blackbird Turdus merula: are there many subspecies?

“…Adult wing length of Balckbirds Turdus merula merula collected from Denmark, Poland, France and Hungary (Møller 1995, Wysocki 2002, Grégoire 2003, Csörgő et al 2017 were used for comparison with North African ones (Rotschild 1921, Vaurie 1955, Selmi 2002. Furthermore, we compared Blackbirds (museums data Table 1, Figure 1) from Maghreb countries to support the differentiation between subspecies using morphometric parameters of individuals.…”