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Egg Losses Caused by Cold Snap in the Black-Headed Gull, Chroicocephalus ridibundus L.

Indykiewicz P.

Polish Journal of Ecology

2015

Vol. 63, nr 3

460--466

Short- and medium-distance migrant birds that return to the breeding grounds early can usually take better-quality territory leading to higher breeding success than of congeners arriving later. On the other hand, early breeders usually have to face severe weather conditions. 109 Black-headed Gulls which had begun laying in a breeding colony (N-Poland) earlier than the remaining 960 females lost 66.2% of eggs because of severely adverse weather. On 9 April 2012 ambient temperature fell to -4.6°C during the first two hours after sunrise (06:00–07:59) resulting in eggs cracking during the adults' first feeding bout after the night. Up to 1 mm wide cracks in eggshells were from 3 mm to 24 mm long; in some eggs the external shell membrane also broke. Pairs that lost eggs did not repeat broods. In this way in 2012 this colony suffered the greatest loss of eggs during its 15-years history. This event showed that even in the temperate climate, adverse weather, a consequence of the global climate change, does have negative impact on life history traits of birds.

Heavy metal concentrations in the tissues of the Black-headed Gull Larus ridibundus L. nesting in the dam reservoir in south-western Poland

Orłowski G.

Polish Journal of Ecology

2007

Vol. 55, nr 4

783-793

Concentrations of heavy metals (lead, cadmium and copper) were measured in several tissues (pectoral muscle, liver, kidney, lung, femur, brain and feather) of the fledglings and adults of black-headed gull Larus ridibundus L. collected in breeding colony (c. 2000 pairs) in south-western Poland (Mietkowski Reservoir; 980 ha). Fourteen birds (5 fledglings and 9 adults) were collected shortly after death (unknown reason of mortality) in June and July 2003. The highest mean ([plus or minus] 1 SD) level of lead was demonstrated in femur samples (42.32 [plus or minus] 31.42 [micro-]g g[^-1] dry weight), whistle the lowest one, in muscle (3.59 [plus or minus] 0.57 [micro-]g g[^-1] d.w.). The highest and the lowest levels of cadmium were in turn demonstrated in kidney (5.51 [plus or minus] 4.90 [micro-]g g[^-1] d.w.) and in muscle (0.31 [plus or minus] 0.22 [micro-]g g[^-1] d.w.), respectively. Liver was the organ with the highest copper accumulation (29.22 [plus or minus] 13.56 [micro-]g g[^-1] d.w.), whereas the lowest amounts of the element were found in femur samples (2.79 [plus or minus] 1.01 [micro-]g g[^-1] d.w.). Among 21 pairs of tissues in which metal concentrations were compared, only in eight cases statistically significant differences between fledglings and adults were recorded. The accumulation of heavy metals in organs of black headed gull was up to c. 81-fold lower than in bottom sediments of this reservoir.