Annual reproductive variation is the central focus of many ecological studies. Variation in reproductive success is an important vital rate to study because it can lead to inferences about population health, extinction risk, human disturbance and habitat quality. The identification of the causes of reproductive variability can help guide conservation and management efforts of a species. In Glacier National Park, Montana I studied causes of annual reproductive variation and behavioral responses to human disturbance in a breeding population of harlequin ducks (Histrionicus histrionicus). Harlequins are rare sea ducks with a Holarctic distribution and winter along rocky coast lines of North America. Females reach reproductive maturity at age 3. At this time they bond with a male that they will breed with for life. Recent band re-sighting has revealed that these ducks can live up to at least 21 years. In spring pairs migrate inland to the females natal montane stream to breed. My study focused on the breeding season from April September on Upper McDonald Creek, Glacier National Park, Montana. My objective was to study 3 potential indirect and direct sources of reproductive variation in Harlequin ducks on this breeding stream; 1) stream flow effects on annual reproductive success, 2) human presence and effects on stream patch occupancy and resource selection, and 3) carry-over effects of physiological measures of body condition, baseline corticosterone levels (primary stress hormone in birds), and integrated measures of corticosterone deposition in feathers. For my first objective I identified 4 different parameters of stream flow that accounted for 32% of the annual variation in reproductive success. I conclude that these parameters will be very sensitive to climate change, making reproduction challenging for harlequins into the future. For my second objective I found greater probability of occupancy of ducks in high human use sites and in stream patches closer to roads. I also found greater occupancy in pool habitat; surprisingly, this pool habitat also had a greater distribution close to road. I conclude from this analysis that there were no strong negative effects of human disturbance on harlequin duck occupy and resource selection, but recommend that harlequin habitat near to human use areas be monitored closely. For my third objective I found that concentrations of corticosterone deposited in feathers grown just prior to reproduction predict reproductive success for that year. I did not find any predictive value of body condition or baseline corticosterone levels. The carry-over effects that I documented in the feathers grown during the prenuptial molt indicate that is an import period that reflects reproductive decision (may be 2 month separation from feather growth to egg lay). These 3 lines of inquiry identified important sources of annual reproductive variation and will help guide management and conservation efforts. I recommend further study to better understand important resources that harlequins select for on the breeding stream and intensive study of harlequin wintering habitat, especially prenuptial molt areas.
| Identifer | oai:union.ndltd.org:MONTANA/oai:etd.lib.umt.edu:etd-06232014-123815 |
| Date | 26 June 2014 |
| Creators | Hansen, Warren Kevin |
| Contributors | Mark Hebblewhite, Lisa Bate, Creagh Breuner |
| Publisher | The University of Montana |
| Source Sets | University of Montana Missoula |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.umt.edu/theses/available/etd-06232014-123815/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Montana or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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