(A) Gujido, (B) Suhaam, (C) Namdongji, and you will (D) Chilsando. Lines hook up new ? 13 C opinions for each private between chick-rearing attacks.
In the place of others four spoonbill variety that can breed in both marine and you may freshwater wetlands, Black-encountered Spoonbills simply reproduce when you look at the aquatic environment, nesting for the uninhabited seaside and you will offshore islets that are discover mostly across the western Korean Peninsula [10, 15, 17]. But not, according to a survey from mature spoonbills foraging in rice paddies and you can intertidal mudflats when you look at the reproduction 12 months, grain paddy foraging peaked in-may, the beginning of the brand new hottie-rearing several months, immediately after which slowly reduced inside the Summer and you will July . However, exactly how many people foraging into the intertidal mudflats improved because the chick-rearing 12 months developed . Most other knowledge toward Black-encountered Spoonbills reproduction to your overseas islets stated that the latest regurgitated diets out-of girls generally made up types coming from freshwater wetlands, even when intertidal mudflats had been available near their reproduction colonies [17, 18]. These initial findings indicated higher reliance upon freshwater wetlands of the Black colored-experienced Spoonbills in early hottie-rearing 12 months, which was said by the restricted osmoregulation feature out-of chicks [17, 18].
Statistical study
To own ? thirteen C study, an entire model are somewhat different from the newest null design (? 2 = , df = 9, p 2 = , df = step 3, p = 0.010) and eliminated most other a couple of-way connections throughout the full model (chick-rearing several months ? reproduction colony: ? dos = 2.14, df = 3, p = 0.544; chick-rearing period ? hatching date: ? 2 = 3.75, df = 1, p = 0.053; S1 Desk). The reduced design shown a mate1 cancellation hefty difference between ? thirteen C thinking between hottie-rearing periods. ? 13 C philosophy on the late hottie-rearing several months were higher 0.75 ± 0.29‰ (95% CI = 0.33–2.85; Fig 3A; S1 and you will S2 Figs) than those toward early chick-rearing months. ? 13 C opinions was drastically different among reproduction colonies (Fig 3B). The least square means of ? 13 C philosophy regarding chicks from inside the Gujido (-twenty two.5 ± 0.93‰) was below those of others three colonies including Suhaam (-16.cuatro ± 0.62‰), Namdongji (-17.step three ± 0.75‰), and you can Chilsando (-17.dos ± 0.50‰; Fig 3B).
The research could not conclusively show or disprove this new hypothesis displayed within the past records one to adults may provide a much bigger freshwater diet proportion during the early hottie-rearing several months because of lower salt endurance one of young chicks. To help you definitively keep the sodium worry theory with these stable isotope analysis, ? 13 C opinions and projected proportion regarding freshwater prey should have revealed straight down sodium consumption otherwise private use of freshwater target at the beginning of chick-expanding several months. However, the range of ? thirteen C showed high convergence involving the early and late chick-rearing symptoms, and lots of of anybody from the Suhaam, Namdongji, and you can Chilsando might have been given with additional marine target than just freshwater victim actually during the early hottie-rearing several months. ? thirteen C and you can ? 15 N Bayesian fusion habits estimated that over 50% of diets in early hottie-rearing several months originated intertidal mudflats in the Suhaam, Namdongji, and Chilsando. Simultaneously, the brand new contribution of each prey style of did not are different dramatically because of the chick-rearing periodparing the brand new estimated share of diet between hottie-rearing symptoms is minimal due to the fact we projected an average contribution of each and every sufferer types of because of the colony and you will chick-rearing period instead of accounting to possess in this-private type into the ? 13 C and ? 15 N. Additionally, i used potential target offer in the design, not study accumulated from the foraging sites from study populations, that could influence new uncertainty of quote. Nevertheless, ? thirteen C beliefs showed that salt intake may possibly not be substantially various other ranging from hottie-rearing symptoms, suggesting an acceptable osmoregulatory ability to consume ong chicks from inside the early increasing months.
Secure isotope research and Bayesian isotope mix design
? thirteen C thinking within Suhaam indicated that chicks hatched later on have been fed way more aquatic prey. That it seasonal improvement in the brand new ratio out-of freshwater diet when you look at the Suhaam was associated with the latest decrease in target accessibility on grain paddies across the breeding 12 months due to mid-seasons water drainage. On the other hand, you will find no high regular trend within the ? 13 C values during the Gujido, Namdongji, and you may Chilsando. Although there has been no in depth studies of the foraging habitats around breeding territories apart from Suhaam, a few observations reported that spoonbills on Namdongji foraged in different version of freshwater wetlands such as reservoirs and you may lakes . Hence, these types of differences are most likely regarding variation inside the reliance upon grain paddies predicated on breeding colonies. Although not, we don’t systematically gather feathers across the hottie-rearing season, together with diversity within the hatching schedules out-of girls differed certainly one of reproduction colonies. Therefore, to find the effect of seasonal changes in foraging environment, the prey supply of chicks at various other hatching times should be reviewed having fun with systematic sampling.