Presentation Title

Investigation of factors limiting age class diversity in native turtles in the Willamette Valley, Oregon

Abstract

Lack of appropriate nesting areas for turtles due to habitat loss is potentially limiting population recruitment at many sites in Oregon. Two species of native turtles, Western painted turtles (Chrysmeys picta bellii) and Western pond turtles (Actinemys marmorata), were once very common in the Willamette Valley of Western Oregon. Extensive habitat loss of nearly half the area of the historic Willamette River floodplain has led to concern about the remaining population size and their listing as sensitive in the Oregon Department of Fish and Wildlife Oregon Conservation Strategy. Data collected and compiled by the Lower Willamette Native Turtle Working Group over the past 10 years indicates that there is a lack of age class diversity in turtles at many sites in the growing Portland Metro region with only adults observed at many locations. Streams in these urban and suburban areas are often highly channelized and groomed to use their banks as public parks, housing or agriculture. It is hypothesized that these land use alterations have left remnant populations of adult turtles in habitat suitable for mature, long-lived animals, but likely without access to appropriate nesting areas and/or adequate juvenile brood habitat leaving little opportunity for successful recruitment of younger age classes into the population. Nesting surveys will be conducted in the spring and summer of 2019 at 20-30 sites of known turtle habitation for evidence of turtle nesting activity to determine if lack of nesting habitat or lack of successful nests are the major limiting factor in population recruitment.

Subjects

Habitat assessment, Wildlife biology, Conservation biology

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Investigation of factors limiting age class diversity in native turtles in the Willamette Valley, Oregon

Lack of appropriate nesting areas for turtles due to habitat loss is potentially limiting population recruitment at many sites in Oregon. Two species of native turtles, Western painted turtles (Chrysmeys picta bellii) and Western pond turtles (Actinemys marmorata), were once very common in the Willamette Valley of Western Oregon. Extensive habitat loss of nearly half the area of the historic Willamette River floodplain has led to concern about the remaining population size and their listing as sensitive in the Oregon Department of Fish and Wildlife Oregon Conservation Strategy. Data collected and compiled by the Lower Willamette Native Turtle Working Group over the past 10 years indicates that there is a lack of age class diversity in turtles at many sites in the growing Portland Metro region with only adults observed at many locations. Streams in these urban and suburban areas are often highly channelized and groomed to use their banks as public parks, housing or agriculture. It is hypothesized that these land use alterations have left remnant populations of adult turtles in habitat suitable for mature, long-lived animals, but likely without access to appropriate nesting areas and/or adequate juvenile brood habitat leaving little opportunity for successful recruitment of younger age classes into the population. Nesting surveys will be conducted in the spring and summer of 2019 at 20-30 sites of known turtle habitation for evidence of turtle nesting activity to determine if lack of nesting habitat or lack of successful nests are the major limiting factor in population recruitment.