(A) Gujido, (B) Suhaam, (C) Namdongji, and you may (D) Chilsando. Contours hook up the new ? thirteen C thinking for every single personal between chick-rearing periods.
In the place of another five spoonbill species that can reproduce in both marine and you can freshwater wetlands, Black-encountered Spoonbills merely reproduce when you look at the aquatic environment, nesting to the uninhabited coastal and you may overseas islets that are discover mainly across the western Korean Peninsula [10, fifteen, 17]. However, considering a survey of mature spoonbills foraging when you look at the grain paddies and you may intertidal mudflats in the breeding season, grain paddy foraging peaked in-may, the start of this new hottie-rearing several months, then slowly diminished from inside the June and you will July . In contrast, how many adults foraging in intertidal mudflats improved due to the fact chick-rearing seasons evolved . Almost every other education on the Black-experienced Spoonbills reproduction towards overseas islets reported that the fresh regurgitated diet of chicks primarily comprised dating mature women variety via freshwater wetlands, in the event intertidal mudflats was indeed offered near its breeding colonies [17, 18]. These types of preliminary conclusions indicated high dependence on freshwater wetlands from the Black colored-faced Spoonbills in early chick-rearing season, that was explained of the restricted osmoregulation feature regarding chicks [17, 18].
To own ? 13 C investigation, the full model was rather distinct from the newest null model (? 2 = , df = nine, p dos = , df = 3, p = 0.010) and you may removed most other a few-way affairs regarding the full model (chick-rearing several months ? reproduction nest: ? 2 = 2.14, df = step three, p = 0.544; chick-rearing months ? hatching big date: ? 2 = step three.75, df = 1, p = 0.053; S1 Dining table). The low design showed a hefty difference in ? 13 C viewpoints anywhere between hottie-rearing symptoms. ? 13 C philosophy to your late hottie-rearing months were large 0.75 ± 0.29‰ (95% CI = 0.33–2.85; Fig 3A; S1 and you will S2 Figs) as opposed to those toward very early chick-rearing months. ? thirteen C values was in fact substantially different one of reproduction territories (Fig 3B). At least square technique of ? thirteen C philosophy regarding chicks during the Gujido (-twenty two.5 ± 0.93‰) had been lower than those of the other around three colonies together with Suhaam (-sixteen.4 ± 0.62‰), Namdongji (-17.step 3 ± 0.75‰), and you may Chilsando (-17.2 ± 0.50‰; Fig 3B).
Our very own studies couldn’t conclusively prove or disprove this new hypothesis displayed within the past reports one grownups could possibly get provide more substantial freshwater eating plan proportion at the beginning of chick-rearing period because of straight down sodium endurance certainly one of younger girls. So you can definitively keep the salt stress theory with this steady isotope data, ? thirteen C thinking plus the projected ratio away from freshwater victim need to have revealed straight down salt intake otherwise personal use of freshwater victim during the early chick-broadening months. But not, the range of ? thirteen C showed large overlap within early and you may later chick-rearing attacks, and lots of of the some body in the Suhaam, Namdongji, and you can Chilsando has been given with an increase of aquatic victim than freshwater prey also in early hottie-rearing several months. ? thirteen C and ? 15 Letter Bayesian mix habits estimated that over 50% of diet in early hottie-rearing period came from intertidal mudflats on Suhaam, Namdongji, and you may Chilsando. At exactly the same time, the fresh new contribution of any prey particular don’t are very different significantly from the chick-rearing periodparing the new estimated share out of diet anywhere between hottie-rearing attacks is limited once the i estimated the common share of each prey form of from the colony and chick-rearing period as opposed to bookkeeping to own inside-private variation in the ? thirteen C and you will ? fifteen N. Additionally, i used possible victim sources throughout the model, perhaps not studies amassed within foraging web sites of data populations, which can determine the new suspicion of estimate. Nevertheless, ? 13 C beliefs revealed that salt consumption is almost certainly not significantly various other between hottie-rearing periods, indicating an adequate osmoregulatory capability to eat ong chicks during the early increasing several months.
Stable isotope study and you can Bayesian isotope combination model
? thirteen C values on Suhaam showed that chicks hatched afterwards were provided a great deal more aquatic target. That it regular change in this new ratio out of freshwater dieting in Suhaam could well be connected with the latest reduction of sufferer accessibility at grain paddies over the reproduction season because of middle-season drainage. On top of that, you will find zero tall seasonal pattern in ? 13 C opinions within Gujido, Namdongji, and you can Chilsando. However, there has been no intricate study of your foraging habitats as much as breeding colonies except for Suhaam, a number of observations reported that spoonbills at Namdongji foraged in almost any particular freshwater wetlands such as for instance reservoirs and you can ponds . For this reason, these variations are most likely linked to version during the reliance on rice paddies based on breeding colonies. However, i failed to systematically collect feathers along side chick-rearing year, therefore the range for the hatching dates of chicks differed certainly one of breeding territories. Therefore, to select the effectation of seasonal alterations in foraging surroundings, new target supply of girls from the more hatching times needs to become examined playing with systematic testing.