James F. Hare

Learn More
Where alarm signals function to warn others of the presence of threat, variation is likely to exist in the reliability of alarm signalers. Some signalers, with too low a threshold of excitation, will issue false alarms and should be ignored if potential alarm recipients are to maximize energy gains. We exposed juvenile Richardson's ground squirrels to(More)
Thyroid hormones affect in vitro metabolic intensity, increase basal metabolic rate (BMR) in the lab, and are sometimes correlated with basal and/or resting metabolic rate (RMR) in a field environment. Given the difficulty of measuring metabolic rate in the field-and the likelihood that capture and long-term restraint necessary to measure metabolic rate in(More)
Plasma membrane proteins of intact mouse 3T3 fibroblasts and H4-II-E-C3 hepatoma cells were separated into two groups based on their compartmentation between the cell surface and an intracellular compartment accessible at 20 degrees C but not at 0 degrees C. One group was derivatized at 0 degrees C with sulfosuccinimidyl(More)
Energy expenditure in wild animals can be limited (i) intrinsically by physiological processes that constrain an animal's capacity to use energy, (ii) extrinsically by energy availability in the environment and/or (iii) strategically based on trade-offs between elevated metabolism and survival. Although these factors apply to all individuals within a(More)
To examine the chemical defense of lepidopteran eggs towards ant predators, eggs of the arctiid moth Utetheisa ornatrix were offered to laboratory colonies of the ant Leptothorax longispinosus. The ants rapidly devoured Utetheisa eggs produced by parents reared on an alkaloid-free diet, but left eggs that had been endowed with parental alkaloid largely(More)
American water shrews (Sorex palustris) are aggressive predators that feed on a variety of terrestrial and aquatic prey. They often forage at night, diving into streams and ponds in search of food. We investigated how shrews locate submerged prey using high-speed videography, infrared lighting, and stimuli designed to mimic prey. Shrews attacked brief water(More)
Female Photuris fireflies contain defensive chemicals of two types. They sequester steroidal pyrones (lucibufagins) from male fireflies of the genus Photinus that they eat, and themselves produce the defensive betaine N-methylquinolinium 2-carboxylate. Chemical analyses of Photuris eggs showed that females that fed on Photinus males endow their eggs with(More)
Richardson’s ground squirrels (Spermophilus richardsonii (Sabine, 1822)) produce audible (ca. 8 kHz) and (or) ultrasonic (ca. 48 kHz) alarm vocalizations that warn conspecifics of impending danger. Audible calls have a larger active space than ultrasonic calls because they travel farther, are louder, and contain frequencies to which conspecific and(More)