FACTORS INFLUENCING ARIZONA BAT POPULATION LEVELS

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Publication Date

January 1972

Abstract

Current (1969 and 1970) estimates were compared with past estimate of numbers of members of over 20 Arizona and northern Mexico bat populations, and trends established. A trend is defined here as the change in numbers of population members between the present estimate and the most recent past estimate in the same month at the same roost site. Thirteen of the populations showed definitive trends: nine "Down", one "Stable-Down", one "Stable”, and two "Up", Eight of the nine populations with "Down" trends contained no live members on the 1969 and 1970 visits, and no signs of members. The ninth contained 1% of the numbers in the present estimate that it had on the most recent past estimate of the same month. Human disturbance was frequently associated with populations showing "Down" trends, while lack of human disturbance was characteristic of stable or increasing populations. Human disturbance directed at the population members, oversampling for biological study probably resulted in the loss of an Antrozous pallidus population. Human disturbance directed at the roost site, modernization of a railroad bridge, resulted in the loss of favored roost site and possibly direct loss of some population members for an Eptesicus fuscus and a Tadarida brasiliensis population.Insecticide residue analysis was performed on 104 samples from 58 bats representing six species: Antrozous pallidus, Eptesicus fuscus, Leptonycteris sanborni, Macrotus waterhousii, Pipistrellus hesperus, and Tadarida brasiliensis. Samples included pooled brains, livers, GX tracts + contents, mammaries, embryos, and remaining whole bodies. Preparation was accomplished by a "Quickie Method" that works particularly well for samples weighing 10 g or less, and analysis by gas chromatography. DDE, DDD, DDT, o,p'-DDT, dieldrin, toxaphene, Aroclor 1254 and Aroclor 1260 were seen in one or more samples. DDE was usually present in greatest concentration. Residues in organs and embryos ordinarily reflected those in their hosts, but in less concentration. Embryo/host r

Keywords

Bats – Arizona, Insecticides -- Physiological Effect, Nature -- Effect Of Human Beings On, Mammals -- Arizona

Document Type

Article

Identifier

SFS0039911_00001

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