(I received a request to comment on birds on the Onrus Estuary and this is how I answered it briefly. - Ed.)
I've been tasked with writing a Situation Assessment on the Onrus Estuary before my contract ends in June, and have been collating available info. The only info I have on birds at this stage is the attached, from the CSIR Estuaries of the Cape series report on the estuary and the Birds in Reserves Project website.
I noticed from one of your articles on the Birdlife Overberg website "SIXTY MINUTE TWITCH AT ONRUS & VERMONT" that you do a weekly count at the Lagoon. Could you perhaps confirm species dominance in the main groups - e.g. gulls and terns, waders, piscivores, waterfowl, plus 'terrestrial' birds like the weavers and swallows? I'm really just wanting to summarise the birdlife in a paragraph or two.
Estuary Management Coordinator Overstrand
Here I am at last. (Not birding weather today). I attach some comment that you can take as introductory. I don't fully understand what you are after, but look at this and let me know what I could elaborate on. I did mark the birds seen here on a checklist and I could get this to you if you are interested.
Let me know if there is anything else that I can help with.
BIRDS AT THE ONRUS LAGOON
Over the last 15 years I had positively identified 152 bird species over and on the Onrus lagoon. These include 17 species that are endemic to southern Africa, 7 that are near-endemic to southern Africa and 27 migratory species. Species that could genuinely be described as vagrant and that were only seen once are White-fronted Bee-eater, African Openbill, Little Blue Heron and Red-billed Tropicbird.
Most of the other birds are fairly common and I briefly comment on issues that might be of interest, even though this could be regarded as being fairly trivial. The many eucalyptus trees and other exotics along the Onrus River are used for breeding by a variety of raptors that include at least African Goshawk, African Harrier-Hawk, Black Sparrowhawk and Little Sparrowhawk. Species that are fairly difficult to find in many parts of the Overberg and that 'twitchers' come to find here include Little Bittern, Purple Heron, Black-crowned Night-Heron, African Purple Swamphen and Southern Tchagra. Also significant that large numbers of Barn Swallows roost in the reedbeds in summer.
Concerns include the presence of Mallards on the lagoon, particularly given the fact that I had photographed several hybrids during the last summer. This matter has been taken up with CapeNature and interventions are been considered. The management of the reeds and the continual problem with effluent will obviously have to be addressed by the municipality. It is believed that the lagoon could be used far more effectively for purposes of birding tourism and this matter will be taken up with conservation and tourism authorities on an on-going basis.