...Mortality rate at birth is high in captive individuals but has not been determined in natural populations... 
Ray D. Burkett 「Natural History of Cottonmouth Moccasin, Agkistrodon piscovorus (Reptilia)」
... (1908:166-173) allocatedall western sirtalis to either parietalis or concinnus, thelatterincluding the populations of the northwest coast in Oregon, Washingtonand British Columbia...
Henry S. Fitch 「Occurrence of the Garter Snake, Thamnophis sirtalis, in the Great Plains and Rocky Mountains」
...Records are lacking from the drainages of the Republican, NorthCanadian, Brazos and Colorado River drainages in the High Plains,but possibly isolated populations occur in some of these also...
Henry S. Fitch 「Occurrence of the Garter Snake, Thamnophis sirtalis, in the Great Plains and Rocky Mountains」
...However, by far the most logical divisionis the Continental Divide; south of the Teton Range it constitutesa broad barrier separating eastern and western populations...
Henry S. Fitch 「Occurrence of the Garter Snake, Thamnophis sirtalis, in the Great Plains and Rocky Mountains」
...In Utah, populations of sirtalis occur in the drainages of the Bear,Weber and Sevier rivers and other smaller streams of the westernhalf of the state...
Henry S. Fitch 「Occurrence of the Garter Snake, Thamnophis sirtalis, in the Great Plains and Rocky Mountains」
...Knowledge of the home range is of value to man when control or propagation of cottontail populations is desired...
Donald W. Janes 「Home Range and Movements of the Eastern Cottontail in Kansas」
...In these cranial characters, specimens from the MesetaCentral are intermediate between the two lowland populations...
William E. Duellman 「Neotropical Hylid Frogs, Genus Smilisca」
...In southern Tamaulipas and eastern San Luis Potosí,these characters vary discordantly, thereby strongly suggesting that thetwo populations intergrade...
John D. Lynch 「A Taxonomic Revision of the Leptodactylid Frog Genus Syrrhophus Cope」
...Lacking evidence of geneticexchange, I prefer to retain disjunct populations that are distinctiveas species...
John D. Lynch 「A Taxonomic Revision of the Leptodactylid Frog Genus Syrrhophus Cope」
...Until contrary evidence isforthcoming, I consider the disjunct populations heretofore held to besubspecies of modestus to be specifically distinct...
John D. Lynch 「A Taxonomic Revision of the Leptodactylid Frog Genus Syrrhophus Cope」
...Contact betweenthe latter two populations was probably fairly regular beforeman's stabilization of the channel of the lowermost reaches of theRio Grande...
Robert K Selander 「Vertebrates from the Barrier Island of Tamaulipas, México」
...Fish populations, following a drought, in the Neosho and Marais des Cygnes rivers of Kansas...
Robert K Selander 「Vertebrates from the Barrier Island of Tamaulipas, México」
...Predation upon grasshoppers, especially in summer and early autumn,benefits the farmer by helping to stabilize populations of grasshoppers...
Dwight Platt 「Food of the Crow, Corvus brachyrhynchos Brehm, in South-central Kansas」
...interfusa Dwight andGriscom breeds in the west, west of stationsin Cloud, Stafford, and Clark counties; a broad zone of intergradationexists between the two named populations...
Richard F. Johnston 「The Breeding Birds of Kansas」
...Lacking materialfrom intermediate localities, describers have given specificrecognition to several of these isolated populations...
Rollin H. Baker 「Mammals taken Along the Alaska Highway」
...There is a continuing demand from sheep ranchers in the county thatfoxes be controlled, yet this species seems to maintain considerablyhigher populations than does the coyote...
Kenneth W. Andersen 「Mammals of Northwestern South Dakota」
..."The nearest populations now are far to the north, and this jumping mouseoccupies only restricted habitats in northwestern South Dakota andadjacent regions...
Kenneth W. Andersen 「Mammals of Northwestern South Dakota」
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