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

Abstract

Numerous studies have explored the relationship between environmental factors and White Stork Ciconia ciconia reproduction, mainly expressing breeding success as the number of fledglings. Nonetheless, one of the most critical life-history stages in birds falls between egg-laying and fledging, and identifying the factors causing offspring mortality during this period provides valuable knowledge. We quantified the number of laid White Stork eggs and the proportion of eggs that turned into fledglings in an agriculture-dominated region in Eastern Germany. Moreover, we identified the factors among land cover, weather and arrival dates, which influenced these two reproductive measures the most, and analysed the monitored mortality causes. On average, four eggs were laid per nest, and 57.8 % of the eggs turned into fledglings. The number of eggs laid was best explained by the negative effect of the arrival date of the second stork, while the percentage of eggs that turned into fledglings was more dependent on weather: most important parameters were mean temperature in the fifth and seventh weeks after the assumed breeding start (i.e. around the assumed hatching date), and the number of consecutive days with precipitation when nestlings are assumed to be approximately 3 weeks old. In an agricultural environment, weather effects that potentially disturb food availability might be more important than effects directly affecting the survival of White Stork offspring. The most frequent observed mortality cause, nest fights, furthermore revealed the relevance of intraspecific competition in the study population.

Distribution and breeding of the White Stork (Ciconia ciconia) in North Macedonia in 2015 and 2016

“…Nesting on trees was nearly abandoned in 2015-2016 with only 0.6%, while nesting on hay bales and stacks was completely abandoned. The first White Stork census found that 37.2% of the nests were placed on trees and 7.52% on hay bales (Jovani & Tella 2004;Denac 2006;Hilgartner et al 2014;Eggers et al 2015) and distance to the main feeding areas (Hilgartner et al 2014;Djerdali et al 2016a) are known to affect the breeding parameters, as is the combination of the en-vironmental factors with colony size (Janiszewski et al 2014;Djerdali et al 2016b), sometimes resulting with density-dependent brood reduction (Zurell et al 2015). These factors might be behind the observed differences in the breeding parameters among some regions in North Macedonia in 2015, but clear correlation between breeding densities and breeding parameters is lacking (Tab.…”

Edge computing for critical environments: Vision and existing solutions

“…Project EVE enables lifecycle management and remote orchestration of any application and hardware, and incorporates a zero-trust security model. Fledge [53] Scalable and secure IIoT open-source platform for building and operating industrial applications for condition monitoring, predictive maintenance, increased ef iciency (Overall Equipment Effectiveness, or OEE), higher quality, situation awareness, and safety. Home Edge [54] Edge computing open-source framework, platform, and ecosystem that provides an interoperable, lexible, and scalable edge orchestration and computing services platform, with APIs that can also be used with libraries and runtimes to enable various user scenarios for the home.…”