RUI: Foraging Behavior and the Role of Social Transmission

获取食物是幼龄动物面临的最关键的问题之一，尤其是早熟的幼体，它们必须在出生后不久就找到正确的食物。考虑到由于觅食行为不当导致的幼鸟因饥饿和捕食而导致的高死亡率，摄食行为的发展是一个重要的研究领域。这些高死亡率表明，为了觅食技能的快速发展，选择压力一定很大。三个因素可能有助于鸡类物种的食物识别：a)先天的啄食偏好，b)味道和营养因素，以及c)社会传递。很可能这三个因素共同作用来增强和加速食物识别和觅食行为的发展。本研究旨在研究一种高山松鸡——白尾松鸡的觅食行为的发展，这种松鸡的早熟雏鸟在孵化后不久就必须在高山冻土带上的各种食物中识别食物种类。影响食物选择的社会因素和营养因素之间的相互关系将是这项研究的主要焦点。初步数据表明，当找到特定的食物时，母鸡会发出独特的叫声（食物叫声）。小鸡通过靠近母鸡的嘴来回应食物的呼唤，并以母鸡正在吃的同种食物为食。此外，引起母鸡食物叫声的植物物种成为小鸡饮食中的主要食物。引起食物鸣叫的食物在营养成分（如蛋白质）上也可能与母鸡吃的其他不引起食物鸣叫的食物不同。因此，问题出现了：母鸡的食物呼叫是否通过社会传播的食物识别来集中小鸡的喂养选择？要研究的第一个假设是，小鸡会更频繁地在那些能引起母鸡鸣叫的食物上觅食，而不是在那些不能引起母鸡鸣叫的食物上觅食，因为鸣叫代表了一种社会传递形式，可以增强小鸡对特定食物的识别。白尾雷鸟是野外研究觅食行为个体发生的理想物种，因为带雏鸡的母鸡适应人类观察者，不愿飞行，场地保真度高，并且在植被高度低、多样性相对较低的高山地区觅食，这些都有利于觅食观察。此外，还记录了成年雷鸟的觅食选择及其营养概况。实验操作在验证假设方面是有利的，但由于各种原因，不可能。然而，这些假设可以通过利用人群中有关食物呼唤的自然变化来彻底调查。种群中的母鸡叫食的频率各不相同，从几乎每次喂食时都会发出叫食的母鸡到从来没有听到过发出叫食的母鸡。因此，代替直接的操作，将在母鸡的窝之间进行比较，表现出不同的食物呼唤与饮食的变化。这项研究是第一批直接解决野生动物在其自然栖息地进行的社会传播功能的研究之一。* * *

Abstract Clarke 9514117 Obtaining food is one of the most critical problems faced by young animals, particularly precocial young that must seek out the correct foods to eat soon after birth. The development of feeding behavior is a critical area of study considering the high mortality rate of juvenile birds attributable to starvation and predation due to inept foraging behaviors. These high mortality rates indicate that selective pressures must be intense for the rapid development of foraging skills. Three factors may contribute to food recognition in gallinaceous species: a) innate pecking preferences, b) taste and nutritional factors, and c)social transmission. It is likely that all three factors operate together to enhance and expedite food recognition and the development of foraging behavior. This study proposes to investigate the development of foraging behavior in an alpine grouse, the White-tailed Ptarmigan, whose precocial chicks must identify food species in the wide array of items presented in the alpine tundra soon after hatching. The interrelationship of social and nutritional factors influencing food choice will be the study's primary focus. Preliminary data indicate that the hens emit unique vocalizations (food calls) when specific items are located. Chicks respond to the food calls by approaching the hen's bill and feeding on the same species she is eating. Further, the plant species that elicit hen food calls become the major items in the chick's diets. The foods eliciting food calls also may differ from other foods eaten by the hen that do not elicit food calls in their nutritional content (e.g. prmtein). Thus the question arises: Do the hens' food calls function to focus the chicks' feeding choices through socially transmitted food recognition? The first hypothesis that will be investigated is that chicks will forage more often on those foods to which elicit hen food calls than they will on foods which do not elicit food calls because the call represents a form of soc ial transmission that enhances the chicks' recognition of specific foods. White-tailed Ptarmigan provide an ideal species for field studies of the ontogeny of foraging behaviors because hens with chicks accommodate to human observers, are reluctant to fly, have high site fidelity, and forage in the alpine where the vegetation is low in stature and relatively low in diversity all of which facilitates foraging observations. Also, the foraging selections of the adult ptarmigan are documented as are their nutritional profiles. Experimental manipulations would be advantageous in testing the hypotheses but are not possible for a variety of reasons. However, the hypotheses can be thoroughly investigated by exploiting natural variations within the population regarding food calling. The hens within the population vary in food calling frequency, ranging from hens that emit food calls during nearly every feeding bout to hens that were never heard to emit a food call. Thus, in lieu of direct manipulations, comparisons will be made between broods of hens that exhibit variations in food calling regarding diet shifting. This research represents one of the first studies to address directly the function of social transmission conducted with wild animals in their natural habitat. ***