The Whiskered Tern Chlidonias hybrida expansion in Poland: the role of immigration

Abstract

The Whiskered Tern population in Poland has rapidly increased from 40 breeding pairs in 1990 to over 1,600 in 2007, with strongest local population in the Upper Vistula River Valley. Owing to rather low pre-breeding and adult apparent survival rates estimated for this population (0.54 and 0.80, respectively) and a delay in accession to reproduction (recruitment completed at age 3), matrix modelling indicated an intrinsic growth rate of k calc = 1.02. Observed growth rates of both the Polish and the Upper Vistula River Valley populations was k obs = 1.29. Using the deterministic population projection matrix including immigrant class, we estimated that, on average, 44 immigrants should enter the Upper Vistula River Valley population annually to match the observed growth. With survival rates increased (U P = 0.63, U B = 0.90) as to mimic no emigration and reduced dispersal, the estimated number of immigrants was only eight, indicating that substantial emigration rates are likely. A majority of the breeding sites were recorded in man-made water bodies. Colonisation has started in the southeast and proceeded towards the northwest. The strong, stable population in western Ukraine may explain high numbers of immigrants that could originate from there. Other factors favouring quick colonisation of Poland include availability of suitable breeding sites, the wide flexibility of the species with respect to breeding habitat, plentiful food, and high breeding success in the Upper Vistula River Valley. It also seems likely that westward shifts in both breeding and wintering ranges could add to the strong population increases in Eastern Europe.Die Ausbreitung der Weißbart-Seeschwalbe (Chlidonias hybrida) in Polen: Rolle der Zuwanderung Die Population der Weißbart-Seeschwalbe (Chlidonias hybrida) in Polen ist von 40 Brutpaaren (1990) sehr rasch auf über 1600 Brutpaare (2007) angewachsen, mit der stärksten örtlichen Population im oberen Weichseltal. Wegen der für diese Population geschätzten, ziemlich niedrigen Ü berlebensrate junger und adulter Vögel (0,54, bzw. 0,80) und der Verzögerung, mit der das Reproduktionsalter erreicht wird (mit 3 Jahren), legen MatrixModelle eine intrinsische Wachstumsrate von k calc = 1,02Communicated by C. Barbraud. Electronic supplementary materialThe online version of this article

Offspring desertion and parental care in the Whiskered TernChlidonias hybrida

“…Similarly, a low level of predation and, in consequence, high breeding success (Betleja , Ledwoń et al . , ; Table ) may not be acting against desertions (e.g. Amat et al .…”

“…Fieldwork took place on seven carp pond complexes (Spytkowice, Bugaj, Rudze, Przeręb, Stawy Monowskie, Adolfin and Tomice) in the Upper Vistula River Valley, southern Poland (for a detailed description of the study area, see Ledwoń et al . , , Gwiazda & Ledwoń ). Each year, we observed one to four colonies containing 15–50 nests and monitored 4–16 nests (nine on average) in each colony.…”

True deception during extra‐pair courtship feeding: cheating whiskered ternChlidonias hybridafemales perform better

“…These extensively managed carp ponds cover over 1000 ha. For a detailed description of the study area, see Ledwoń et al (2013Ledwoń et al ( , 2014Ledwoń et al ( , 2015Ledwoń et al ( , 2016 and Gwiazda and Ledwoń (2015).…”

Peer Review #2 of "Reproductive success of Whiskered Tern Chlidonias hybrida in eastern Spain in relation to water level variation (v0.1)"

“…Manuscript to be reviewed chosen area for reproduction by parents, the reproduction in colonies or as isolated nests, the climatic conditions, the water level variation in the wetlands and its stability during the reproduction period, the abundance of food (Tucker & Heath, 1994;Catry et al, 1997;Carpentier et al, 2002); the type, form and size of the nests, the presence of parasites and predators, the type of vegetation on which the nests are anchored and its abundance (Spina, 1982;Dostine & Morton, 1989;Bakaria et al, 2002;Latraube, 2006;Paillisson et al, 2006;Bakaria et al, 2009;Ledwoń et al, 2014); and the quality of cares that parents provide to their descendence (Nichols et al, 1990;Spendelow et al, 1995, Brunton, 1997Lebreton et al, 2003;Paillisson et al, 2007;Alvarez & Barba, 2008;Monticelli et al, 2008;Braasch et al, 2009;Ledwoń et al, 2013). When all these conditions are suitable, the reproductive success is usually high.…”