The effect of migration strategy and food availability on White StorkCiconia ciconiabreeding success

Abstract

In the mid 1970s, the breeding populations of the migrant White Stork Ciconia ciconia were close to extinction in the northeastern region of France (Alsace). A re‐introduction project was implemented, resulting in the year‐round settlement of some individuals in the region, which rely on additional food supplied by humans during the winter. Today, both resident and migrant birds breed in the same areas and take food from rubbish dumps and humans (farmers). The effects of these anthropogenic influences, altering Stork behaviour, on Stork reproductive success are not known. The aim of this study was to test the influence of bird status (resident vs. migrant) and food availability (control nests vs. nests that benefit from high food supply) on reproductive success. In control nests, the mean laying date was earlier in resident than in migrant White Storks. There was also a clear seasonal decline in clutch size. For all nests, the numbers of eggs and hatchlings were higher in resident birds than in migrants, which can be attributed to the earlier breeding of resident Storks. The large broods of resident birds showed a high mortality rate, leading to the same fledgling success (fledglings/hatchlings) and number of fledglings as in migrants. Fledgling success and the number of fledglings were higher for nests close to a reliable food supply. In summary, although resident birds can breed earlier and produce more eggs than migrants, we found no advantage in terms of number of fledglings. The higher mortality rate of chicks found in pairs with a large brood could be caused by the deterioration of their habitat. Thus, the year‐round settlement of Storks may not present a biological advantage if the quality of their habitat is not guaranteed by the conservation of their grasslands.

Timing of arrival at breeding grounds determines spatial patterns of productivity within the population of white stork (Ciconia ciconia)

“…This hypothesis was also supported by food supplementation experiments which demonstrated that, at least in some populations, reproductive success of white storks is limited by the food availability during the breeding season (Djerdali et al 2008). Similarly, it was found that stork pairs occupying territories with unlimited anthropogenic food supplies and negligible intra-specific competition (e.g., near rubbish dumps) had higher reproductive success in comparison to pairs that exploited natural food resources, even if their territories were of good quality (Tortosa et al 2002;Massemin-Challet et al 2006). We also found a tendency for the negative density-dependent effects to occur during the years of delayed population arrival at breeding grounds, which further supports the link between the phenology of spring migration and spatial patterns of productivity within the populations of white stork.…”

Garden Bird Feeding: Insights and Prospects from a North-South Comparison of This Global Urban Phenomenon

“…However, even among the well-studied examples such as Eurasian blackcaps Sylvia atricapilla (Plummer et al, 2015) and white storks Ciconia ciconia (Massemin-Challet et al, 2006), it is difficult to disentangle various other potential influences such as the effects of climate change.…”

To fledge or not to fledge: factors influencing the number of eggs and the eggs-to-fledglings rate in White Storks Ciconia ciconia in an agricultural environment

“…Schulz 1998;Massemin-Challet et al 2006;Djerdali et al 2008;Kosicki 2010;Vergara et al 2010). We found that the number of eggs was best explained by the arrival date of the second stork at the nest, rather than by local weather or land cover.…”

“…Due to their low thermoregulation abilities during the first 3 weeks after hatching, the semi-altricial White Stork nestlings are particularly sensitive towards cold and wet weather conditions, which can lead to hypothermia (Tortosa and Castro 2003;Jovani and Tella 2004;Kosicki 2012;Gordo et al 2013), and make them more susceptile to diseases (Olias et al 2010). Favourable feeding conditions, on the other hand, promote White Stork reproductive outcome (Tortosa et al 2002;Massemin-Challet et al 2006;Hušek et al 2013) by stimulating both the number of eggs laid (Sasvári and Hegyi 2001;Djerdali et al 2008) as well as nestling development (Kosicki and Indykiewicz 2011). White Storks forage preferentially in wet open landscapes with short vegetation (Alonso et al 1991;Dziewiaty 2005), where their principal food consists of insects, earthworms, amphibians and voles (Antczak et al 2002).…”