Heavier rumen-reticulum organs in white-tailed deer (Odocoileus virginianus) is consistent with dietary bulk not quality

The organs that make up the gastrointestinal tract have high energy demands. Therefore, when these organs vary in mass, they should impact metabolic requirements. Mass of the rumen-reticulum organs, the organs that comprise the largest part of the gastrointestinal tract of ruminants, might vary from bulk or nutrient availability of the diet. We examined differences in mass of the rumen-reticulum organs in white-tailed deer (Odocoileus virginianus (Zimmermann, 1780)) from two sites in Texas, USA, with different diet types. Specifically, at one site deer were fed a pelleted ration and at the other site deer consumed a natural browse diet Accounting for body mass, deer consuming the browse diet had rumen-reticulum organ masses that were about 1.7 times heavier than deer consuming the pelleted diet. Deer consuming the browse diet also had lower diet quality, as indexed by crude protein concentration, than deer consuming the pelleted diet. The digesta loads of deer, however, were similar for the two types of diet. Our study findings are consistent with increased mass of rumen-reticulum organs from greater bulk, not diet quality. Understanding variation in rumen-reticulum organ mass has implications for understanding energy conservation in white-tailed deer

Benefits for Dominant Red Deer Hinds under a Competitive Feeding System: Food Access Behavior, Diet and Nutrient Selection

Social dominance is widely known to facilitate access to food resources in many animal species such as deer. However, research has paid little attention to dominance in ad libitum access to food because it was thought not to result in any benefit for dominant individuals. In this study we assessed if, even under ad libitum conditions, social rank may allow dominant hinds to consume the preferred components of food. Forty-four red deer hinds (Cervus elaphus) were allowed to consume ad libitum meal consisting of pellets of sunflower, lucerne and orange, and seeds of cereals, corn, cotton, and carob tree. The meal was placed only in one feeder, which reduced accessibility to a few individuals simultaneously. During seven days, feeding behavior (order of access, time to first feeding bout, total time spent feeding, and time per feeding bout) were assessed during the first hour. The relative abundance of each meal component was assessed at times 0, 1 and 5 h, as well as its nutritional composition. Social rank was positively related to the amount of time spent feeding during the 1st h (P = 0.048). Selection indices were positively correlated with energy (P = 0.018 during the 1st h and P = 0.047 from 1st to 5th) and fat (only during the 1st h; P = 0.036), but also negatively with certain minerals. Thus, dominant hinds could select high energy meal components for longer time under an ad libitum but restricted food access setting. Selection indices showed a higher selectivity when food availability was higher (1st hour respect to 1st to 5th). Finally, high and low ranking hinds had longer time per feeding bout than mid ones (P = 0.011), suggesting complex behavioral feeding tactics of low ranking social ungulates

Weak Polygyny in California Sea Lions and the Potential for Alternative Mating Tactics

Female aggregation and male territoriality are considered to be hallmarks of polygynous mating systems. The development of genetic parentage assignment has called into question the accuracy of behavioral traits in predicting true mating systems. In this study we use 14 microsatellite markers to explore the mating system of one of the most behaviorally polygynous species, the California sea lion (Zalophus californianus). We sampled a total of 158 female-pup pairs and 99 territorial males across two breeding rookeries (San Jorge and Los Islotes) in the Gulf of California, Mexico. Fathers could be identified for 30% of pups sampled at San Jorge across three breeding seasons and 15% of sampled pups at Los Islotes across two breeding seasons. Analysis of paternal relatedness between the pups for which no fathers were identified (sampled over four breeding seasons at San Jorge and two at Los Islotes) revealed that few pups were likely to share a father. Thirty-one percent of the sampled males on San Jorge and 15% of the sampled males on Los Islotes were assigned at least one paternity. With one exception, no male was identified as the father of more than two pups. Furthermore, at Los Islotes rookery there were significantly fewer pups assigned paternity than expected given the pool of sampled males (p<0.0001). Overall, we found considerably lower variation in male reproductive success than expected in a species that exhibits behavior associated with strongly polygynous mating. Low variation in male reproductive success may result from heightened mobility among receptive females in the Gulf of California, which reduces the ability of males to monopolize groups of females. Our results raise important questions regarding the adaptive role of territoriality and the potential for alternative mating tactics in this species

ERP evidence for different strategies in the processing of case markers in native speakers and non-native learners

BACKGROUND: The present experiments were designed to test how the linguistic feature of case is processed in Japanese by native and non-native listeners. We used a miniature version of Japanese as a model to compare sentence comprehension mechanisms in native speakers and non-native learners who had received training until they had mastered the system. In the first experiment we auditorily presented native Japanese speakers with sentences containing incorrect double nominatives and incorrect double accusatives, and with correct sentences. In the second experiment we tested trained non-natives with the same material. Based on previous research in German we expected an N400-P600 biphasic ERP response with specific modulations depending on the violated case and whether the listeners were native or non-native. RESULTS: For native Japanese participants the general ERP response to the case violations was an N400-P600 pattern. Double accusatives led to an additional enhancement of the P600 amplitude. For the learners a native-like P600 was present for double accusatives and for double nominatives. The additional negativity, however, was present in learners only for double nominative violations, and it was characterized by a different topographical distribution. CONCLUSION: The results indicate that native listeners use case markers for thematic as well as syntactic structure building during incremental sentence interpretation. The modulation of the P600 component for double accusatives possibly reflects case specific syntactic restrictions in Japanese. For adult language learners later processes, as reflected in the P600, seem to be more native-like compared to earlier processes. The anterior distribution of the negativity and its selective emergence for canonical sentences were taken to suggest that the non-native learners resorted to a rather formal processing strategy whereby they relied to a large degree on the phonologically salient nominative case marker

The genetic mating system of a sea spider with male-biased sexual size dimorphism: evidence for paternity skew despite random mating success

Male-biased size dimorphism is usually expected to evolve in taxa with intense male–male competition for mates, and it is hence associated with high variances in male mating success. Most species of pycnogonid sea spiders exhibit female-biased size dimorphism, and are notable among arthropods for having exclusive male parental care of embryos. Relatively little, however, is known about their natural history, breeding ecology, and mating systems. Here we first show that Ammothella biunguiculata, a small intertidal sea spider, exhibits male-biased size dimorphism. Moreover, we combine genetic parentage analysis with quantitative measures of sexual selection to show that male body size does not appear to be under directional selection. Simulations of random mating revealed that mate acquisition in this species is largely driven by chance factors, although actual paternity success is likely non-randomly distributed. Finally, the opportunity for sexual selection (Is), an indirect metric for the potential strength of sexual selection, in A. biunguiculata males was less than half of that estimated in a sea spider with female-biased size dimorphism, suggesting the direction of size dimorphism may not be a reliable predictor of the intensity of sexual selection in this group. We highlight the suitability of pycnogonids as model systems for addressing questions relating parental investment and sexual selection, as well as the current lack of basic information on their natural history and breeding ecology

Examining hypotheses about feeding strategies of white-tailed deer

Examined whether the forage abundance hypothesis or the selective quality hypothesis could explain the feeding strategies of Odocoileus virginianus on Hatchie National Wildlife Refuge and the Ames Plantation, Tennessee. The botanical composition of the diets on Ames was characterized by agricultural crops, browse, and acorns in autumn and winter, and browse, forbs, and agricultural crops in spring and summer. Acorns were common in autumn and winter diets on Hatchie, as were browse and agricultural crops. Spring and summer diets were high in browse and forbs and, to a lesser extent, agricultural crops. Diets were lower in crude fat, crude protein, and fiber in spring and higher in most nutritional parameters in autumn and winter at both sites. Neither the nutritional value nor the abundance of forages had a strong impact on diet in many of the seasons and years of the study as predicted by the forage abundance hypothesis. Spearman\u27s correlation coefficients of forage consumption and abundance in spring and summer were positive and much higher than in autumn and winter at both sites. Deer are apparently less selective during seasons of lower dietary fiber and higher forage abundance. Data support the selective quality hypothesis. -from Author

Examining hypotheses about feeding strategies of white-tailed deer

A study was carried out to determine whether the forage abundance hypothesis or the selective quality hypothesis could explain the feeding strategies of white-tailed deer (Odocoileus virginianus) on Hatchie National Wildlife Refuge in Haywood County at the Ames Plantation in Fayette and Hardeman counties, Tennessee. The study was conducted from autumn 1983 to summer 1986. Overall, the data support the selective quality hypothesis as a more appropriate model of feeding strategies for white-tailed deer

Assessment of selected forest factors and lake level in raccoon management

The purposes of this study were to assess the relationship of capture frequency of raccoons with selected forest factors and to examine (over 15 years) the association of particular hunting variables on a wildlife management area with water level of a large on-site lake. Additionally, the authors provide an estimate of raccoon density in a lowland hardwood forest