Assessing temporal trends in contaminants from long-term avian monitoring programs: the influence of sampling frequency.
The effect of sampling frequency on the detection of statistically significant temporal trends in egg contaminant levels was examined using data from the Great Lakes Herring Gull Monitoring Program. Decreased identification of statistically significant trends was apparent in the sampling regimes where samples were collected less frequently. When statistically significant declines were observed, sampling at two and four year intervals resulted in the trend being identified later than with annual monitoring. The design of monitoring programs must balance costs and data quality. Programs should ensure that the data collected are adequate to address critical questions.
Hebert
Craig E
CE
Canadian Wildlife Service, National Wildlife Research Centre, 100 Gamelin Blvd., Hull QC, Canada K1A 0H3. craig.hebert@ec.gc.ca
Weseloh
D V Chip
DV
D000818:Animals; D000835:Animals, Wild; D001717:Birds; D003625:Data Collection; D004784:Environmental Monitoring / Q000379:methods* / Q000706:statistics & numerical data*; D004785:Environmental Pollutants / Q000032:analysis*; D006114:Great Lakes Region; D009930:Organic Chemicals / Q000032:analysis; D010063:Ovum / Q000737:chemistry; D015203:Reproducibility of Results; D012107:Research Design; D013997:Time Factors
D004785:Environmental Pollutants; D009930:Organic Chemicals