Feeding Strategy

Elasmosaurs were extremely long-necked, aquatic reptiles that used four flippers for locomotion. Their distinctive long neck distinguishes them from all other Mesozoic forms, yet the potential uses and constraints of this structure are poorly understood, particularly with regard to feeding. Several associated series of elasmosaurian cervical vertebrae were used to measure ranges of potential flexion. Two-dimensional models, based on a complete specimen of the Late Cretaceous elasmosaur Aphrosaurus furlongi, were created to measure mobility in both vertical and horizontal planes. Accuracy of the models was assessed through comparative analyses with currently extant vertebrate analogues (e.g. snake, turtle, seal). Results suggest that the elasmosaurian neck was capable of a 75–177° ventral, 87–155° dorsal, and 94–176° lateral range of movement depending upon the thickness of cartilage reconstructed between each vertebra. Neck postures such as a ‘swan-like’ S-shape are shown to be implausible because they require N360° vertical flexion. However, maintenance of a straight neck while swimming, together with considerable lateral and/or ventral movement during prey capture and feeding are feasible.

Research showed a positive association between back fat (BF) change the week before farrowing and colostrum yield (CY). This study tested the causality of this association, hence to optimize CY by altering the sows' peripartal feeding strategy. Sows were randomly divided into 2 treatment groups at d 108 of gestation. The first group (L, n = 28) received 1.5 kg feed·d(-1), the second group (H, n = 22) received 3 times 1.5 kg feed·d(-1) until farrowing. Daily feed intake and CY were measured. Colostrum was analyzed for nutrient composition, AA and fatty acids, IgG and IgA. Sow serum was obtained at d 108 of gestation and d 1 of lactation after overnight fasting and analyzed for NEFA, (iso)butyrylcarnitine (C4), creatinine, urea, 3-OH-butyrylcarnitine (3-OH-C4), IgG, and IgA. Based on BF at d 108, sows were divided into body condition (BC) groups: skinny (<17 mm, n = 15), moderate (17 to 23 mm, n = 21), fat (>23 mm, n = 14). We performed ANOVA with treatment and BC as fixed f...

Kleptoparasitism involves the theft of resources such as food items from one individual by another. Such food-stealing behaviour can have important consequences for birds, in terms of individual fitness and population sizes. In order to understand avian host-kleptoparasite interactions, studies are needed which identify the factors which modulate the risk of kleptoparasitism. In temperate European intertidal areas, Eurasian oystercatchers (Haematopus ostralegus) feed primarily on bivalve molluscs, which may be stolen by kleptoparasitic species such as carrion crows (Corvus corone) and herring gulls (Larus argentatus). In this study we combined overwinter foraging observations of oystercatchers and their kleptoparasites on the Exe Estuary, UK, with statistical modelling to identify the factors that influence the likelihood of successful food stealing behaviour occurring. Across the winter, 16.4 % of oystercatcher foraging attempts ended in successful kleptoparasitism; the risk of theft was lowest in February (10.8 %) and highest in December (36.3 %). Using an information theoretic approach to compare multiple logistic regression models we present evidence that the outcome of host foraging attempts varied with the number of kleptoparasites per host within the foraging patch for two out of five individual months, and for all months grouped. Successful, kleptoparasitism was more likely to occur when the total number of all kleptoparasites per host was greater. Across the entire winter study period, oystercatcher foraging attempts that resulted in kleptoparasitism were associated with a mean number of kleptoparasites per host that was more than double that for foraging attempts that ended in the oystercatcher successfully consuming the mussel. Conversely, the stage of the tidal cycle within the estuary did not affect the outcome of oystercatcher foraging attempts. Our study provides evidence that bird numbers influence the risk of kleptoparasitism within avian assemblages.