Decline in Egg Production of Glaucous-Winged Gulls Over the Last Century
Author Information
Author(s): Louise K. Blight
Primary Institution: Centre for Applied Conservation Research, University of British Columbia
Hypothesis
Long-term food web changes may affect the life history traits of glaucous-winged gulls over time.
Conclusion
The study found significant declines in both egg size and clutch size of glaucous-winged gulls over the past century, likely due to reduced food availability.
Supporting Evidence
- Mean egg size decreased by approximately 5% from 1902 to 2009.
- Clutch size declined from an average of 2.82 eggs in 1962 to 2.25 eggs in 2009.
- First egg dates have become later, with a shift from May 15 to May 22 over the decades.
Takeaway
Gulls are laying smaller eggs and fewer eggs in their nests now than they did a long time ago, which might be because there isn't enough food for them.
Methodology
The study used meta-regression to analyze historical and modern data on egg size and clutch size from various sources.
Potential Biases
Potential bias from the selection of studies and data sources may affect the results.
Limitations
The study's findings may be influenced by the limited number of studies included and the reliance on historical data.
Participant Demographics
The study focused on glaucous-winged gulls in the Salish Sea region of British Columbia and Washington.
Statistical Information
P-Value
0.007
Confidence Interval
95% CI = -0.06–-0.01
Statistical Significance
p<0.001
Digital Object Identifier (DOI)
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