Relationship between avian abundance and measures of river impairment in central Texas

Background/Question/Methods

Since 1999, the Upper Cibolo Creek in central Texas has been cited multiple times as impaired in the Texas Integrated Report by the Texas Commission of Environmental Quality.  This impairment led to the formation of the Upper Cibolo Creek Watershed Partnership (UCCWP) which purpose is to restore water quality along the Upper Cibolo Creek.  To assist the UCCWP a survey of avian fauna was undertaken to determine if a correlation between avian abundance and impairment indicators exists.  In October and early November four ten-minute modified point counts were completed by two independent counters at four locations along the Upper Cibolo Creek near Boerne, Texas.  Using previously collected water sample data, correlation analyses was performed between mean number of birds and 1) total Kjeldahl nitrogen and 2) total phosphorous levels.  

Results/Conclusions

Mean number of birds and total Kjeldahl nitrogen showed a significant positive correlation (P < 0.0001; r = 0.9057).  Mean number of birds and total phosphorous showed a significant positive correlation (P < 0.0001; r = 0.9881).  Also total Kjeldahl nitrogen and total phosphorous showed a significant positive correlation (P < 0.0001; r = 0.9146).  With positive correlations between avian community abundance and water impairment indicators, there is a suggestion that avian communities may be contributing to creek impairment. Further studies are needed determine if the birds are a point source of contamination of the Upper Cibolo Creek watershed.