Honey bee (Apis mellifera) foragers can remember both the location and time of day food is collected and, even in the absence of a reward, reconnoiter the food source at the appropriate time on subsequent days. This spatiotemporal memory (time-memory) is linked to the circadian clock and enables foragers to synchronize their behavior with floral nectar secretion rhythms, thus eliminating the need to rediscover productive food sources each day. Here, we asked whether the establishment of one time-memory influences the formation of another time-memory at the same time of day. In other words, can two time-place memories with the same ‘time-stamp’ coexist? We simultaneously trained two groups of foragers from a single hive to two separate feeders at the same restricted time of day. After 5 days of training, one feeder was shut off. The second feeder continued being productive 4 more days. Our results showed that (1) foragers with high experience levels at the first source were significantly more likely than low-experience foragers to maintain fidelity to their original source and resist recruitment to the alternative source, (2) nearly one-third of foragers demonstrated multiple, overlapping time-memories by visiting both feeders at the correct time and (3) significantly more high-experience than low-experience foragers exhibited this multitasking behavior. The ability to maintain and act upon two different, yet contemporaneous, time-memories gives the forager bee a previously unknown level of versatility in attending to multiple food sources. These findings have major implications for understanding the formation and management of circadian spatiotemporal memories.

Daily rhythms occur in numerous physiological and behavioral processes across an immense diversity of taxa, but there remain few cases in which mechanistic links between rhythms of trait expression and organismal fitness have been established. We construct a dynamic optimization model to determine whether risk allocation provides an adaptive explanation for the daily foraging rhythm observed in many species using the orb-weaving spider Cyclosa turbinata as a case study. Our model predicts that female C. turbinata should generally start foraging at lower levels of energy reserves (i.e., should be less bold) during midday when predators are most abundant. We also find that individuals’ foraging efficacy determines whether daily rates of encounters with predators or prey more strongly influences boldness under high risk. The qualitative model predictions are robust to variation in our parameter estimates and likely apply to a wide range of taxa. The predictions are also consistent with observed patterns of foraging behavior under both laboratory and field conditions. We discuss the implications of our study for understanding the evolution of daily rhythms and the importance of model predictions for interpreting empirical studies and generating additional hypotheses regarding behavioral evolution.

Northern Goshawk breeding habitat was conceptualized and analyzed as a system composed of different sized components organized within a hierarchy. The organization of the hierarchy was asymmetric with smaller components nested within and subordinate to larger components. Components considered in the breeding habitat hierarchy of goshawks were nest tree, nest site, nest territory, foraging area, and landscape. Choice at any level within the hierarchy was contrasted with the next level in the hierarchy. Thus it was found that goshawks chose nest trees with a largerdbh (79.0 ± 4.4 cm) than the nest site average (43 ± 2.7 cm) (p=0.000036); the averagedbh of the nest site (43.2± 3.1 cm) was significantly larger than the territory (33.2± 1.9cm) (p=0.018). The nest territory when contrasted with random unoccupied locations in the landscape demonstrated a composition of a central site of trees with largedbh and fewer stems when compared with the surrounding forest. I hypothesize that this pattern reduces thepredation risk at the nest site. I investigated the nest site relative to the assumed foraging area (radius of 3000m; approximately 3000ha). Goshawks selected nest sites which were significantly further from young clear cuts (>10 ha). The average distance from a nest site to a recentclearcut greater than 10 ha was 1,350 m of the nest while for unoccupied sites the average distance was 770 m (p = 0.011). Finally, at the landscape level, areas of approximately 10,000 ha, goshawks on Vancouver Island were more abundant, had more nest sites, and had higher productivity per active nest in old growth forests (>120 years) than in either second growth (majority less than 80 years) or fragmented landscapes. The majority of goshawk prey, as determined though pellet analysis was red squirrel (69%). Red squirrels were equally abundant in second growth and old growth yet less abundant in fragmented landscapes. Despite similar abundance of their main prey item goshawks were not as abundant in second growth forests as in old growth forests. I conclude that the structure of second growth and fragmented landscape reduces the availability of key prey species and therefor the suitability of these landscape fpr goshawks is lower. / Graduate

The semiaquatic mammals - amongst them the beaver Castor fiber - are inhabitants of the land-water-ecotone, which is characterized by length and low depth.Due to specific adaptations to their habitats, semiaquatic mammals are highly dependent on the specific structures and resources of the ecotone riverbank. Anthropogenic influences on the ecotone riverbank often cause destruction of the resources that leads to a decrease of structural diversity.Being a primary consumer, the beaver mainly uses the water as a medium for locomotion and escape. The equipment of the riverbank, mainly the bankside vegetation, is of great importance concerning foraging. The presence and the quantity of certain biofacts like feeding or cutting places and scent mounds give a hint on the value of different structures and resources of the bankside with regard to certain modes of behaviour. They also give information on different qualities of the used and unused parts of the bankside.Biofacts of beaver-activity were recorded along 20 km of riverbank during a five-year-period. The results of the statistical analysis show that beavers - concerning species-specific mode of behaviour - prefer certain riverbank structures. Biofacts and near-natural structures such as steep bank, riparian forest and willows correlate significantly positive whereas biofacts and anthropogenic structures as slope, farmland or absence of woody plants show significantly negative correlation. There is a strong connection between the number of biofacts - that is use of the riverbank or slope - and structural diversity. Based on these results, an eco-ethological model has been developed which makes it possible to predict behaviour in dependence on the specific structures and resources of the banks and slopes of anthropogenic influenced streams.

Small-ruminant production is an important part of the agricultural economy of northeastern Brazil. However, mild-to-severe undernutrition of livestock is an annual occurrence. Goats can tolerate the marginal forage conditions better than sheep, but the mechanisms underlying their superior tolerance are not understood. An analysis of animal liveweights at the end of the year-long study indicated that reproducing mixed-race goats gained nearly twice (P<.05) the weight of reproducing hair-sheep of the Santa Ynez breed, and non-reproducing goats gained about 1.2 times more (P<.05) weight than non-reproducing sheep. Daily weight gains of lambs were less (P<.10) than those of Kids for their first 80 days of life. In the wet season, reproducing sheep and goats gained similar (P>.05) weight, while non-reproducing sheep gained more (P~.05) than non-reproducing goats. Non-reproducing goats had greater (P<.05) forage organic matter intake (OMI) than the corresponding sheep in the two wet periods. In the late-wet period, non-reproducing goats had greater (P<.05) digestible energy intake (DEI) than corresponding sheep did but had similar (P>.05) digestible protein intake (DPI) as sheep. In the dry season, reproducing sheep and goats lost similarbn(P> . 05) weight but only the five better performing sheep were weighed at the end of the dry season. The five poorer performers were removed from the study and given supplemental feed to keep them alive. The non-reproducing sheep lost weight during the dry season, while the non-reproducing goats gained weight . Non-reproducing sheep and goats had similar (P>.05) OMI and DEI during the dry periods. In the late-dry period when forage quality was lowest, the animals experienced their greatest weight loss, and both species had greatly reduced DPI; the goats had 83 percent greater (P<.05) DPI than the sheep. Digestion trials were conducted with actual diet samples selected by free-ranging animals. Goats had greater (P<.05) crude protein apparent digestibility than sheep in the late-dry period trial. This difference may be a key aspect explaining their responses to the dry season.

Mule deer provide recreational bunting to a large number of sportsmen in Utah, and also have a high aesthetic value. Prior to settlement, deer are believed to have wintered in the valleys and lower foothill areas. However, in northern Utah agricultural development bas removed many valleys and lower foothill areas from the available winter range. The winter deer range in this area has therefore been restricted to a relatively small area of foothill country, and low elevation mountain slopes and benches.

In Somalia, camel (Camelus dromedarius) survivability and milk production has been higher than for other domestic livestock and contributes substantially to the subsistence of Somali pastoralists. The objective of this research was to study management, foraging behavior and nutrition of camels in their natural habitat to determine how production continues under seasonal nutritional stress. Management systems of Ceeldheer pastoralists are based on available natural pasture and water. The natural rotation grazing system maintained an ecological equilibrium in the District. Pastoralists manipulate their herds to suit existing environmental conditions, family needs and labor availability for herding. In herd management, control of breeding males and preferential treatment to increase the female component of the herd are geared to secure continuous milk supply for the family. Camels were watered only in the dry seasons. They foraged continuously throughout the day the first few days after watering, but foraged mostly in the morning and evening as watering days approached. The quantity of water camels consumed in summer and winter dry seasons were similar. In winter, milking camels foraged more, travelled shorter distance and rested less than dry ones. In fall, 1986, and spring, 1987, lactating camels spent less time foraging than non-milking animals. Foraging time was the same for both groups in summer 1986, 1987 and fall, 1987. Camels spent more time chewing bones in summer of 1986 in Xarar foraging area than other seasons. Low or high relative humidity together with hot temperature apparently reduced foraging time, increased rumination and idling times in winter and spring seasons. As forage availability declined, camels ingested a broader array of dietary items in the dry seasons and consumed large amounts of herbaceous plants. The diets of milking and dry camels were similar. Lactating camels consumed more green forage than dry camels in the dry seasons. Shrubs and trees comprised major components of the diets (80.9%). Physical structures of plant species did not prevent feeding on the plants. Camel diets were rich in crude protein (cp), calcium (Ca), potassiuim and sodium. Phosphorus (P) was deficient. Ca:P ratios were extremely low. Neutral detergent fiber and acid detergent lignin were high. CP intake seemed adequate year round assuming camel protein requirements are similar to other livestock requirements. Digestible energy was deficient in dry seasons. Low energy intake, inadequate phosphorous availability and water deprivation were probably responsible for the weight loss of camels as the dry season progressed.

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第20429号 / 農博第2214号 / 新制||農||1048(附属図書館) / 学位論文||H29||N5050(農学部図書室) / 京都大学大学院農学研究科森林科学専攻 / (主査)教授 吉村 剛, 教授 藤井 義久, 教授 矢野 浩之 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

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