Location: Warmwater Aquaculture Research UnitTitle: Feeding behavior and diet of free ranging black crowned night herons on a catfish aquaculture facility in Mississippi) Author
Submitted to: Southeastern Association of Fish and Wildlife Agencies Conference
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2011
Publication Date: 12/31/2010
Citation: Taylor, J.D., Cooper, A.L., Barras, S.C., Chatakondi, N.G., Jackson, J.R., Riffell, S.K., West, B.C. 2010. Feeding behavior and diet of free ranging black crowned night herons on a catfish aquaculture facility in Mississippi. Southeastern Association of Fish and Wildlife Agencies Conference. 64:118-124. Interpretive Summary: The impact of piscivorous bird, black-crowned night heron, Nycticorax nycticorax was assessed by a bi-weekly survey (Oct 2004 to Sept 2006) on a commercial catfish aquaculture facility in Mississippi to quantify year around patterns of free-ranging night heron presence, stomach content analyses and nocturnal behavior. The presence of night herons on aquaculture facilities was concentrated during summer and early fall, approximating 85 birds per bi-weekly period. The most common behavior observed was standing and waiting with peak abundance occurring in September. Stomach content of night herons revealed the abundance of catfish fingerlings, predating mostly on the ponds that had distressed fingerlings prone to disease conditions. This study provides the insight on the predatory impact of night heron on aquaculture production facilities. Night herons’ ability to rapidly exploit distressed catfish fingerlings during disease outbreaks may prevent farm managers from capturing the true loss to disease in their inventories. This study documented the use of aquaculture production facility as a foraging area, however the economic impact and compensatory mortality of fingerlings warrants additional studies.
Technical Abstract: The impacts of many species of piscivorous birds on aquaculture are well documented in the southeastern United States; however, specific studies of black-crowned night heron (Nycticorax nycticorax) in these areas are lacking. It was observed that black-crowned night herons opportunistically exploit abundant food resources and inhabit an important catfish production area. We initiated a study to assess their use of and potential impacts on a catfish aquaculture facility. A biweekly survey from October 2004–September 2006 on Harvest Select Farms near Inverness, Mississippi was conducted to quantify year-round patterns of free-ranging night heron presence and collected 75 night herons for stomach content analysis. We also documented nocturnal behavior by night herons twice weekly June–September 2004–2006 on these ponds. During the summer and early fall each year, we observed approximately 85 night herons per biweekly survey. The most common behavior observed on ponds each year was standing and waiting. Night herons numbers declined at Harvest Select Farms beginning in November and use of ponds ended by January of each year. Night heron use resumed in late spring (April 2005) or summer (June 2006) with peak abundance occurring in September of each year. Stomach content analysis (n = 75) revealed 72% of stomachs contained catfish fingerlings, ranging from 0–26 fingerlings/stomach. Mean number of catfish/stomach (n = 63) was 3.95 (SE = 0.58). Mean length of fingerlings was 9.8 cm (n = 159, SE = 0.19), and mean weight was 11.0 g (n = 159, SE = 0.59). A review of pond health records revealed that 53% of birds collected were on diseased ponds. Mean number of fingerlings found in stomachs of night herons collected on diseased ponds (4.36; SE = 0.99) was greater than healthy ponds (2.14; SE = 0.37; t40 = 2.09, P = 0.043). Night herons’ ability to rapidly exploit distressed catfish fingerlings during disease outbreaks may prevent fisheries managers from capturing the true loss to disease in their inventories. Although we documented consumption of catfish and use of the farm as a foraging area, their actual economic impact is unknown without additional studies to assess the issue of compensatory mortality.