allows males to relocate their territories from resource sites to prominent sites such as hilltops, various protrusions, or trees. At this point, pheromones may direct the female into the territory founded by males. Short-range marking of the signal by the female bee attracts them to male territory just before copulation will occur. Competition among males for non resource sites may lead to adaptations that continue to evolve until one male has an advantage over the other. There are various factors that affect X. sonorina fidelity rates. First, high mortality rates of resident males is significantly correlated with frequent turnover rates and decreased site fidelity. Second, male density affects site fidelity. As the ratio of rivals to suitable territories rises, competition for territorial control increases, which leads to frequent turnover. In contrast, if there are few replacements for territory owners, there will be evidence of increasing site fidelity. For X. sonorina, the prevalence of days of very low territorial occupation and a few days of high male density in "lek" conditions resulted in decreasing fidelity. Another aspect of the environment that affects site fidelity is the quality of territorial sites. Finally, fluctuating or declining territory value should reduce the extent of site fidelity. The extent to which female territorial preferences remain constant throughout the mating season will be very important in territory value. Males are expected to abandon territories at times when they no longer have the potential to produce offspring. It is also conceivable that in X. sonorina, the quality of the male's sex pheromone may be a key feature determining his sexual attractiveness. Most males of X. sonorina did not exhibit site fidelity, while few males exhibited strong attachment to their original sites. Thermoregulation An unusual characteristic of X. sonorina is their ability to thermoregulate at temperatures beyond the range of other bee species that have been tested; they can fly at very high temperatures without overheating and at low temperatures without freezing. By modifying their foraging patterns and flying between different altitudes depending upon temperature, the valley carpenter bee is able to adapt to very different environments. Xylocopa sonorina maintain thoracic temperatures of 33.0 to 46.5 °C while traveling through environments with 12.0 to 40.0 °C. Since the thoracic temperature is not constant the bees are thermoregulating. There is physiological transfer of large amounts of heat to the abdomen and to the head during pre-flight warming and thoracic