BIRD DIVERSITY AT WHISBY NATURE PARK

I have recently spent a day observing and identifying birds at Whisby Nature Park, Lincoln for the Conservation of Biodiversity module of my course. The point of the study was basically to see whether lakes with different characteristics have an effect on, 1) the average total count of birds observed, 2) the average species richness, 3) The average Simpson and 4) Shannon Diversity Indices.


Whisby Nature Park is a 150 hectare Local Nature Reserve made up of flooded gravel pits of different sizes and characteristics. The two lakes chosen for the study were Thorpe Lake and Grebe Lake, which are significantly different from each other. Thorpe Lake is very deep, with steep sloping sides and has an almost constant water level all year round. Grebe Lake is of varying depths with many islands and shallow margins.

Grebe Lake

Observations were carried out for 5 mintues, then a 5 minute rest period before the next 5 mintue observation period. This was done 5 times on each lake and all species seen on the water during the observation period recorded. All of the data was collected and analysed.


Results showed an obvious increase in numbers of birds on Grebe Lake with 1976 birds seen, and only 826 seen on Thorpe Lake (P=0.003). Species Richness was also greater in Grebe Lake (P=0.046) and the same can be said for the Simpson Diversity (P=0.042). Shannon Diversity showed no significant difference however (P=0.743). I'm not sure why this is. It could be that I calculated the Shannon Diversity indices wrong in the first instance, therefore effecting the results of the statistical analysis.

There are a number of bird species that favour flooded gravel pits as their general habitat, such as the Mallard (Anas platyrhynchos), Tufted Duck (Aythya fuligula), Pochard (Aythya farina), Gadwall (Anas strepera), Coot (Fulica atra), Moorhen (Gallinula chloropus), Grest-crested Grebe (Podiceps cristalus), Canada Goose (Branta Canadensis) and the Cormorant (Phalacrocorax aristotelis) in winter (Sterry 2004).

In general, Grebe Lake shows higher numbers and diversity of species. This could be due to its varying levels of depth. The shallows provide excellent feeding habitat for dabbling birds (birds that filter the first few centimetres of water) such as Shovelors (Anas strepera) and Wigeons (Anas penelope) (Guillmain, Martin & Fritz 2002).  The mid depth and deeper waters are great for diving birds such as the Tufted duck, Pochard, Goldeneye (Bucephala clangula) and Coot. The tufted duck feeds primarily on molluscs (Olney 1963), pochard usually feed on water plants such as Charophytes (Olney 1968), and the Goldeneye usual diet is pondweed (Jones & Drobney 1986), as is the Coots.


Male Tufted Duck

The mid depth waters are the perfect habitat for these species, and they were therefore seen in greater numbers than on Thorpe Lake. There is also a much greater number of Gulls at Grebe Lake, again due to the shallower water levels and the availability of food. Gulls also winter inland, and feed on human refuse (Horton, Brough & Rochard 1983). Whisby Nature Park has a visitor centre with a café so there will be refuse coming from the centre, as well as Lincoln and other town nearby with plenty of refuse.

Weather conditions should also be taken into account. It was very windy on the day the observations were carried out, and Thorpe Lake appeared to be a lot less sheltered and the water was slightly rough. Grebe Lake was more sheltered by surrounding foliage and the water appeared calmer. The ducks may have chosen the more sheltered of the two lakes on this particular day. Also, the time of year causes fluctuations in numbers due to influxes of birds from Europe (Sterry 2004) which would have effected the number observed.

The assessment could be made more accurate by doing observations at different times of day and maybe over a number of weeks or months. This would give a more accurate picture of the actual numbers of birds and the numbers of species that visit the lake. Doing the assessment over a number of weeks would give us an indication of which animals are more common on the lakes during the winter months. The assessment could be carried out at different times of year to give an example of species found throughout the year but at different times. This would give an overall greater picture of the diversity at the lakes. 

References:

Guillmain M., Martin G.R., Fritz H (2002) Feeding methods, visual fields and vigilance in dabbling ducks (Anatidae). Functional Ecology 16(4):522-529.

Horton N., Brough T., Rochard J.B.A. (1983) The Importance of Refuse Tips to Gulls Wintering in an Inland Area of South-East England. Journal of Applied Ecology 20(3):751-765.

Jones J.J., Drobney R.D. (1986) Winter Feeding Ecology of Scaup and Common Goldeneye in Michigan. The Journal of Wildlife Management 50(3):446-452.

Olney P.J.S (1963) The Food And Feeding Habitats of Tufted Duck, Aythya Fuligula. Ibis 105(1):55-62.

Olney P.J.S (1968) The food and feeding habits of the Pochard, Aythya farina. Biological Conservation 1(1):71-76.

Sterry P (2004) Collins Complete Guide to British Birds. HarperCollins Publishers Ltd. ISBN: 978-0-00-723686-2.