Fremgen, Aleshia Lynn

University of Missouri: MOspace

Public AbstractFirst Name:AleshiaMiddle Name:LynnLast Name:FremgenAdviser's First Name:JoshuaAdviser's Last Name:MillspaughCo-Adviser's First Name:MarkCo-Adviser's Last Name:RumbleGraduation Term:FS 2014Department:Fisheries & WildlifeDegree:MSTitle:LEK ECOLOGY OF MALE GREATER SAGE-GROUSE IN CARBON COUNTY, WYOMINGGreater sage-grouse (Centrocercus urophasianus, hereafter “sage-grouse”) have been experiencing range-wide population declines for several decades, and as a result they are considered warranted for listingunder the Endangered Species Act.  Therefore, wildlife managers need to understand how sage-grousebreeding behavior influences long-term reproductive success and therefore population abundance, andmanagers should be able to accurately relate breeding ground (i.e. lek) count data to populationabundance.  Breeding behaviors, such as how frequently males visit their leks or move among leks, couldrelate to a male sage-grouse’s ability to establish dominance at his lek and mate, so it is important tounderstand conditions and environments in which these behaviors may change.  Additionally, some malesare not seen by observers performing lek counts, and it is important to understand why the individual maynot have been seen and counted to improve lek count protocols.  We investigated why and when a malewould attend a lek, move to a different lek, or be detected during a lek count.  A male had about a 16% to 82% chance that he would attend a lek any day, with high annual variability. This challenges our ability to use a lek count as an index to the population size because of the substantialchanges from year to year in the number of males that are not detected on leks because they are notattending leks.  Attendance was influenced most strongly by date and precipitation, with males less likely toattend with more precipitation.  Broad time-scale precipitation and weather patterns also shifted the peakdate of attendance, with males attending earlier in the season when conditions were dry and warm andlater in the season when conditions were wet with high snowpack.  Males had less than a 3% chance they would move to a new lek on any given day, demonstrating highfidelity as expected for a lek-breeding bird.  However, the yearly probability of moving to a new lek rangedfrom about 40% - 70% per year, suggesting many males may move at some point during the season. Dominant males were less likely to move to a new lek, likely because they had high attendance andestablished themselves at their preferred lek and therefore would be more likely to mate.  Males were lesslikely to move during precipitation, but more likely to move following precipitation.  Precipitation was alsolikely tied to elevation and time of season, as males moved more to higher elevation leks and at thebeginning of the season when conditions were likely clearing up at higher elevation leks.  Male sage-grouse were most likely to be detected on leks with shorter sagebrush, with higher snow coverand more bare ground, and when the observer is at or below the elevation of the lek.  The averagedetection rate across all leks was 87.0%, and there was little variation in lek-specific detection rates rangingfrom 77.1% - 92.8%.  Detection should not vary from one lek to another to be a useful index, so the lekcount may be used as an index for population estimates without concern about detection of males missedby observers during lek counts.  However, when accurate population size estimates are necessary,sightability methods can be used to determine detection rates and more accurately estimate populationsizes.

Lek ecology of male greater sage-grouse in Carbon County, Wyoming

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University of Missouri: MOspace