Many decisions in the lives of animals and humans require a fine balance between the exploration of different options and the exploitation of their rewards. Do you buy the advertised car, or do you testdrive different models? Do you continue feeding from the current patch of flowers, or do you fly off to another one? Do you marry your current partner, or try your luck with someone else? The balance required in these situations is commonly referred to as the exploration-exploitation tradeoff. It features prominently in a wide range of research traditions, including learning, foraging, and decisionmaking literatures. Here, we integrate findings from these and other often-isolated literatures in order to gain a better understanding of the possible tradeoffs between exploration and exploitation, and we propose new theoretical insights that might guide future research. Specifically, we explore how potential tradeoffs depend on (1) the conceptualization of exploration and exploitation; (2) the influencing environmental, social, and individual factors; (3) the scale at which exploration and exploitation are considered; (4) the relationship and types of transitions between the two behaviors; and (5) the goals of the decision maker. We conclude that exploration and exploitation are best conceptualized as points on a continuum, and that the extent to which an agent's behavior can be interpreted as exploratory or exploitative depends upon the level of abstraction at which it is considered.

It is generally assumed that birds’ choice of structurally suitable materials for nest building is genetically predetermined. Here, we tested that assumption by investigating whether experience affected male zebra finches’ (Taeniopygia guttata) choice of nest material. After a short period of building with relatively flexible string, birds preferred to build with stiffer string while those that had experienced a stiffer string were indifferent to string type. After building a complete nest with either string type, however, all birds increased their preference for stiff string. The stiffer string appeared to be the more effective building material as birds required fewer pieces of stiffer than flexible string to build a roofed nest. For birds that raised chicks successfully, there was no association between the material they used to build their nest and the type they subsequently preferred. Birds’ material preference reflected neither the preference of their father nor of their siblings but juvenile experience of either string type increased their preference for stiffer string. Our results represent two important advances: (i) birds choose nest material based on the structural properties of the material; (ii) nest material preference is not entirely genetically predetermined as both the type and amount of experience influences birds’ choices.

No abstract

It is assumed that many birds attempt to conceal their nests by using camouflage. To our knowledge, however, no previous experimental studies have explicitly tested this assumption. To explore whether birds choose materials that match the background colors of nest sites to reduce the conspicuousness of their nests, we offered nest-building male Zebra Finches (Taeniopygia guttata) a choice of nest materials that either matched or did not match the color of their nest cup and the surrounding cage walls. Males chose to nest predominantly with material that matched the background color of the cage. To our knowledge, this is the first experimental evidence that birds actively select materials that camouflage their nests. Keywords: background matching, birds, camouflage, choice, nest, Zebra Finch Las aves construyen nidos camuflados RESUMEN Se piensa que muchas aves intentan ocultar sus nidos usando camuflajes. Hasta donde sabemos, sin embargo, no hay estudios experimentales que hayan evaluado explícitamente esta hipótesis. Para evaluar si las aves eligen materiales que hacen juego con el color de fondo del sitio de ubicación del nido, de modo de reducir su visibilidad, les ofrecimos a machos de Taeniopygia guttata que estaban construyendo el nido la posibilidad de elegir entre materiales del nido que hicieran juego o no con el color de sus nidos y con las paredes de sus jaulas. Los machos eligieron predominantemente materiales que coincidieron con el color de fondo de sus jaulas. Hasta donde sabemos, este es la primera evidencia experimental de que las aves seleccionan activamente material que camufla sus nidos.

In cooperatively breeding species, the level of investment in young can vary substantially. Despite receiving considerable research attention, how and why investment in young varies with cooperatively breeding group members remains unclear. To investigate the causes of variation in care of young, we assessed patterns of both helper and parental behavior in the cooperatively breeding Western Australian magpie (Cracticus tibicen dorsalis). Observations of 19 helpers and 31 parents provisioning 33 broods raised in 11 different groups over two consecutive breeding seasons revealed substantial variation in offspring care behavior. Our results suggest that the level of investment in young by helpers is strongly influenced by group size, chick age, and individual helper traits (including foraging efficiency, age and sex). Helping behavior was facultative, and individuals from smaller groups were more likely to invest in helping behavior. Overall, the number of broods receiving help was lowest during the nestling phase and highest during the fledgling phase. Female helpers provided more care than both male and juvenile helpers. We found that mothers invest more time in offspring care than do fathers, however fathers increase their effort in the presence of helpers while mothers do not. Overall, helper care was additive to parental care and therefore helping behavior may be beneficial to the brood. Our research reveals that variation in offspring care in magpies is influenced by both social and individual traits.

Abstract. Building a structurally robust nest is crucial for reproductive success in many birds. However, we know little about the criteria birds use to select material or where they go to collect it. Here we observed the material collection of male Cape Weavers (Ploceus capensis). Males typically selected long, strong material to build their nests and each male collected material from different locations. Males that built more nests nested in a different area of the colony and flew further to collect nest material than did males that built fewer nests. As these males that flew further to collect material had longer tails and wings and attracted more females to their territories than did males that flew shorter distances, they may have traded off the travel costs of collecting nest materials with benefits gained from holding a territory in a more 'desirable' part of the colony. Nest construction, then, appears to be a multi-dimensional task whereby birds take into account material's structural properties, material proximity to the nest site and territory quality. Males that do this effectively both attract more mates and provide structurally sound nests for their young.

No abstract

There is quite a lot of evidence demonstrating that birds will choose the location in which they build their nest and they will even modify nest location choice based on decisions made by conspecifics or heterospecifics. We know considerably less, however, about whether birds learn which materials with which to build or how to manipulate that material into an appropriate structure. This seems surprising, given how important the nest is to most birds’ reproductive success. There is some evidence that birds will learn about materials during their early development and, recently, that they will change their material choice in response to the reproductive outcomes of those choices. This experience-dependence is at odds with the still-predominant view that nest building is genetic. The most likely explanation for this view, however, is that we have so few data, observational or experimental, concerning nest-building decision making.