Effectiveness of alarm-distress calls for frightening herons from a fish rearing facility

  • Published source details Andelt W.F. & Hopper S.N. (1996) Effectiveness of alarm-distress calls for frightening herons from a fish rearing facility. The Progressive Fish-Culturist, 58, 258-262.


This study is summarised as evidence for the following.

Action Category

Scare birds from fish farms

Action Link
Bird Conservation
  1. Scare birds from fish farms

    A before-and-study in May-June 1993 at a trout-rearing farm in Colorado, USA (Andelt & Hopper 1996), found a 48% reduction in  black-crowned night heron Nycticorax nycticorax numbers following the broadcasting heron alarm/distress calls for 11 days (pre-treatment average 77 birds; treatment 40; post-treatment 69). However, numbers and the proportion remaining increased from nights over the treatment phase, indicating habituation. Great blue heron Ardea herodias numbers were unaffected (pre-treatment 15; treatment 13; post-treatment 16. Herons were counted during six pre-treatment (12-13 to 18-19 May 1993), five treatment (21-22 May to 31 May-1 June 1993), and five post-treatment (1-2 to 11-12 June 1993) nights. Calls were broadcast through each night of the 11 day treatment period: 15-sec sequences of night heron calls followed by 14 min without calls, then a similar sequence of great blue heron calls.


Output references
What Works 2021 cover

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 21

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.

Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape ProgrammeRed List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Mauritian Wildlife Supporting Conservation Leaders
Sustainability Dashboard National Biodiversity Network Frog Life The international journey of Conservation - Oryx Cool Farm Alliance UNEP AWFA Bat Conservation InternationalPeople trust for endangered species Vincet Wildlife Trust