No abstract

Information on the distribution and current status of 25 species or subspecies of mammals occurring in Nebraska are presented. The species covered include one shrew, an armadillo, eight bats, 10 rodents (including two subspecies of one species), three carnivores, and one artiodactyl. Distributional information reported includes the first state record for one species (Sorex nanus) and new county records for 18 species. In Nebraska, we know that mammals are shifting their geographic ranges with some extending populations into the state, whereas others are expanding their geographic ranges within the state. The current status of six additional mammalian taxa in Nebraska is documented, providing knowledge important to the conservation of these species during this time of shifting environmental conditions. The concern is that some mammals have suffered population declines since the 1940s and may have a contracting geographic range as well in the state. These species would be endangered and could be lost to the mammalian fauna of the state. Extensive data on reproduction in these mammals are presented and the taxonomy of species is updated from the 1964 Mammals of Nebraska by Jones.

The relative success of nesting pairs of the Northern Oriole (lcterus galbula) with second-year (SYM) and after-second-year (ASYM) males was investigated on a 120- hectare area near Hays, Ellis County, Kansas during 1981 and 1982. Clutch size, fledging success, and fledging period were examined. Sixty-one nests studied had an overall success rate of 93.1%, with 83.3% for SYM nests and 95.6% for ASYM nests. Nests with SY males had significantly smaller clutch sizes (P < 0.01) and significantly fewer fledglings (P < .05). Nests with SY males had a mean clutch size of 2.7 +- 0.52 and fledged 1.6 +- 1.30 nestlings. Nests with ASY males had a mean clutch size of 5.0 +- 0.54 and fledged 3.7 +- 1.16 nestlings. In 01/01/1981 all nestlings fledged in a 19-day period, whereas 27 days were required in 1982. The less synchronous fledging in 1982 probably was due to inclement weather, causing some pairs to renest, and might have increased the success rate of SYM nests somewhat. Nests of SY males did not begin fledging until more than half the ASYM nests had fledged. Other factors discussed include first arrival dates, renesting, predation, cowbird parasitism, territoriality, the role of non-breeding individuals, and the effect of inexperience of first year breeders. Data were insufficient to determine whether SYM nests were more vulnerable than ASYM nests because of these factors.