JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.Abstract. Feeding strategies of the little brown bat, Myotis lucifugus, were investigated in southern New Hampshire USA from early May through late August 1974. Nightly food consumption was estimated by comparing mean prefeeding body weights with postfeeding weights taken as individuals returned to the roost from their first feeding period (at 2200 to 2400 h) and from a subsequent foraging period (at 0330 to 0500 h). Pregnant bats consumed an average of 2.5 g of insects (2.72 kJ/g prefeeding body weight) nightly, lactating females ate 3.7 g (4.23 kJ/g), and juveniles ingested 1.8 g (2.47 kJ/g). Increased food consumption in lactating bats accommodated reproductive energy demands and was facilitated by rising food availability. Increasing levels of independent food consumption in juveniles accompanied weaning.Fecal analysis revealed that diets of individual bats were diverse. All available insects 3 to 10 mm in body length were accepted as food items. Nematoceran Diptera were by far the most common insects taken in light-trap samples, and constituted a major portion of the diet throughout the summer. Coleoptera, Trichoptera, Lepidoptera, Ephemeroptera, and Neuroptera were also consumed in appreciable numbers.Comparison of dietary composition with prey availability indicates that pregnant bats consumed 3-10 mm prey in approximate proportions encountered during June, when insect availability was low and unpredictable. However, lactating, postlactating, and nonreproductive Y Y exhibited more selective feeding in July, when insects were more abundant. This increase in selectivity reflected exploitation of beetles and mayflies, which were uncommon in trap samples. In August, juveniles approximated random feeding patterns, as they learned to forage. We suggest that increased resource availability allowed selective feeding in adult bats during July, as predicted by prey selection models. However, reduced discriminatory abilities may prevent similar levels of prey selection in juveniles.

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The insectivorous bat Myotis lucifugus typically apportions the night into two foraging periods separated by an interval of night roosting. During this interval, many bats occupy roosts that are used exclusively at night and are spatially separate from maternity roosts. The proportion of the night which bats spend roosting, and thus the proportion spent foraging, vary both daily and seasonally in relation to the reproductive condition of the bats, prey density, and ambient temperature. A single, continuous night roosting period is observed during pregnancy. During lactation, females return to maternity roosts between foraging bouts, and night roosts are used only briefly and sporadically. Maximum use of night roosts occurs in late summer after young become volant. Superimposed upon these seasonal trends is day-to-day variation in the bats' nightly time budget. Long night roosting periods and short foraging periods are associated with cool nights and low prey density. This behavioral response may minimize energetic losses during periods of food scarcity.

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Acrolein was examined as an alternative fixative to formaldehyde for immunocytochemical localization of neuropeptides in the rat brain. A brief (5 min) vascular perfusion with a 5% acrolein solution allowed the identification of thyrotropin-releasing hormone (TRH), vasoactive intestinal peptide (VIP), somatostatin (SRIF), neurotensin (NT), methionine enkephalin (Menk), adrenocorticotropic hormone (ACTH), tyrosine hydroxylase (TH), and luteinizing hormone-releasing hormone (LHRH) in fibers and perikarya within the central nervous system of the rat using the peroxidase-antiperoxidase (PAP) technique. Acrolein appears to be particularly valuable for immunocytochemistry, as it 1) stabilizes heterogeneous peptides and proteins rapidly and effectively, 2) retains antigenicity, and 3) preserves morphological detail.