O papel das rotas e da obtenção de informações sobre a eficiência no forrageio de dinoponera quadriceps em ambiente natural

In this study, we investigated the role of routes and information attainment for the queenless ant species Dinoponera quadriceps foraging efficiency. Two queenless ant colonies were observed in an area of Atlantic secondary Forest at the FLONA-ICMBio of Nisia Floresta, in the state of Rio Grande do Norte, northeastern Brazil, at least once a week. In the first stage of the study, we observed the workers, from leaving until returning to the colony. In the second stage, we introduced a acrylic plate (100 x 30 x 0,8 cm) on a selected entrance of the nest early in the morning before the ants left the nest. All behavioral recordings were done through focal time and all occurence samplings. The recording windows were of 15 minutes with 1 minute interval, and 5 minute intervals between each observation window. Foraging was the main activity when the workers were outside the nest. There was a positive correlation between time outside the nest and distance travelled by the ants. These variables influenced the proportion of resource that was taken to the nest, that is, the bigger its proportion, the longer the time outside and distance travelled during the search. That proportion also influenced the time the worker remained in the nest before a new trip, the bigger the proportion of the item, the shorter was the time in the nest. During all the study, workers showed fidelity to the route and to the sectors in the home range, even when the screen was in the ant´s way, once they deviated and kept the route. The features of foraging concerning time, distance, route and flexibility to go astray by the workers indicate that decisions are made by each individual and are optimal in terms of a cost-benefit relation. The strategy chosen by queenless ants fits the central place foraging and marginal value theorem theories and demonstrate its flexibility to new informations. This indicates that the workers can learn new environmental landmarks to guide their routes

Uso de rotas na área de uso e a relação com comportamento alimentar em Callithrix jacchus

Callithrix jacchus are small primates that live in cooperative reproductive family groups. They explore their home range in search of fruits, exudates and animal prey. In this study we investigate the existence of traveling routes and its relation with the feeding habits in a group of Callithrix jacchus. The group was followed for 6 months in an area of Atlantic secondary Forest at the FLONA-ICMBio of Nísia Floresta, Rio Grande do Norte. Two observers in alternated days collected data referring to the group s location using a GPS navigation device, plotting data in 5 minute intervals, and with a position accuracy under 9 meters. All behavioral recordings were done through focal time samplings. The recording windows were 15 minutes with 1 minute intervals. The main activity was foraging, which propelled the animals to explore the environment with inconsistent intensity through the months, and correlated with the location of fruits, exudates and sleeping sites. From another standpoint, most activities were focused in the core areas that featured most sleeping sites, exudates trees and fruit trees. Insects, mostly Orthopterans, were hunted in all areas. The greater ratio of movement was registered during the last hours of sunlight, when animals returned to the sleeping sites and ate a greater number of fruits. The spatial and seasonal distribution of fruits forced the animals to travel long routes. The capacity to remember the location and navigate efficiently through feeding sources is important to save energy and time costs. Learning and familiarizing with the environment through the use of landmarks and acquisition of new information is extremely important to increase the chances of survival in a constantly changing environment

Finding the way home: movement of butterflies in non-familiar habitats

Paisagens naturais tem sido afetadas dramaticamente pela perda de habitat e fragmentação, os quais transformam paisagens contínuas em manchas de habitat circundadas por áreas de não-habitat (matrizes). Essas matrizes, inóspitas ou não, afetam incontáveis processos ecológicos, como a dispersão. Uma das formas de compreender o efeito da matriz no processo de dispersão é estudando o alcance da percepção do habitat dos animais, o qual é definido como o alcance (distância) em que um animal pode perceber elementos da paisagem. Essa percepção está diretamente relacionada ao sucesso de chegada à um novo habitat, enquanto o animal navega por uma matriz. Nós avaliamos a percepção do habitat em Heliconius erato, uma borboleta tropical. Entretanto nós também estávamos interessados em avaliar o efeito da idade das borboletas e do tipo de matriz na percepção do habitat. Consequentemente, nós criamos borboletas em laboratório e pareamos com borboletas coletadas na floresta durante um experimento de soltura. Para determinar o alcance da percepção, nós realizamos solturas em duas diferentes matrizes (coqueiral e campo em regeneração) à três distâncias da floresta (0,30 e 100 metros) e medimos o ângulo final alcançado pelas borboletas. Nós encontramos que (I) borboletas soltas na borda se orientaram fortemente para a floresta; (II) quanto maior a distância de soltura, menor a habilidade de perceber o habitat e (III) há interação entre matriz e idade da borboleta. Borboletas inexperientes se orientaram melhor no campo aberto (alcance da percepção: 30-100 metros) e experientes se orientaram melhor no coqueiral (alcance da percepção entre 30-100 metros).