You will be interested to know that this simple device was originally invented to scare seagulls and cormorants (shags) off boats, yachts and wharves. So successful, it was quickly tried in many other situations including Ducks and Cormorants landing on Dams or fish ponds.
In most situations these hawks will work provided the Ducks and Cormorants can see the Hawk profile above them from where they are landing. That means, it will work during the day but if the Cormorants or ducks are landing on your dam or pond at night the Hawk won't work unless it is floodlit.
As far as Duck and Cormorants control at night goes the best I can do is ask you to write to Shirley De Silva. He is a great bloke, very honest and will do the right thing by you. He has a lighting system that is used for control of the ducks at night. His address is; Shirley De Silva, PO Box 236 Scone NSW 2337, Australia. Telephone
However if your Ducks and Cormorants are using your dam during daylight hours then a Hawk bird scarer will be of great benefit to you going on past experience. To make your Hawks work.......All you need to do is to install the Hawks high above the area near the dam. There is two methods. I have enclosed information on both. In brief you can either spike the Hawk on the end of a 6 metre length of 20 to 25 mm dia plumbers pipe and stand the hawk and pipe up on the edge of your dam or fish pond near the areas where the water birds are most likely to land.
Alternatively you can use strong fishing line or thin wire to suspend the hawk between trees or other tall points. You will obtain excellent results using this method. The Hawk is unique because it is a full size imitation hawk made of durable weatherproof plastic. As birds instinctively fear the Hawk they are also scared to come within sight of the profile of this replica of a hovering Hawk....Provided the Cormorants and Ducks are scared off before they land on the water. You see once a Cormorants or ducks land on the water it feels perfectly safe. Even if a real Hawk came and hovered overhead they know that if the hawk swooped that it would only have to dive under water and it could escape. However by scaring the Cormorants before they have a chance to land on the water you don't have to worry about them gaining the safety of the water.
From previous customer experience in similar situations I can say that a Hawk Bird Scarer will work for you during daylight hours. If it doesn't, we offer you a money back guarantee. You need a number of scarers depending on the number of dams and area that you are trying to protect. Make sure you concentrate your efforts on the areas most prone to Cormorants. It is usual for Cormorants to come from nearby trees, bush or stream towards your dam and so it is usually the perimeter area on one or two sides that you need to protect. They usually fly up a gully and over the dam wall. If this is the case than the dam wall is the location which needs to have the Hawk. It will be the same Cormorants coming day after day.
There is one other system of suspending a Hawk Bird Scarer, which you may like to consider. This is where a large Helium balloon is used to lift the hawk high above the ground, just like a real soaring Hawk. This balloon is big with a diameter of more than a metre. We have have approval from CASA, the civil aviation authority to use a Helium balloon under which you can suspend a hawk. The balloon can be tethered 50 metres in the air and it will protect 4 to 8 hectares (10 to 20 acres) of dams. This method is very effective but requires light winds.
This new Helium Balloon is expensive but comes fully rigged with every thing except the balloon gas which is available form your local BOC agent. Just look in the yellow pages under "Gas Industrial or Medical". However the new balloons last for a long while and only need a top up with balloon gas every week.