鳥喙和食性的關係 Bird Bills and Feeding Behaviours
例子：白腰杓鷸（Numenius arquata），沙錐（Gallinago sp.)
Through billions of years of evolution, organisms would evolve certain body structures and physiques to adapt to the environment, and thus increase their chance of survival. One of the most obvious examples of such evolution is the bills of birds, which vary in shape and size. This has a lot to do with the feeding behaviour of the bird species. For instance, birds that feed on fish will evolve bills that are best for catching fish. However, even if sharing the same food source, different birds have different strategies and methods. This would also result in different bill shapes. In this article we shall look at the relationship between bird bills and bird feeding behaviours, through observing birds in Hong Kong with different food sources.
Birds that feed on fish
Fishing comes in many different ways. Herons (family Ardeidae) have long dagger-like bills, which they use to pierce fish. Cormorants (family Phalacrocoracidae) have long bills, which are hooked downwards at the end. This allows them to hook onto slippery fish bodies.
Example: Grey Heron (Ardea cinerea)
Birds that feed on relatively larger vertebrates
Birds of prey (orders Falconiformes and Strigiformes) hunt prey that are often too large to be devoured whole. Hence, they have developed thick curved bills to tear their prey into smaller pieces.
Example: Eastern Buzzard (Buteo japonicus)
Birds that feed on mud flat invertebrates
Sandpipers (family Scolopacidae) usually probe muddy shores with their long bills to look for invertebrates like shrimps and slugs. Different bill lengths and shapes allow different sandpipers to hunt prey at different water depths. This is an example of niche differentiation.
Examples: Eurasian Curlew (Numenius arquata), Snipe (Gallinago sp.)
Birds that feed on plankton
Northern Shovellers have wide flat bills with comb-like structures on the edge. This feature enables them to skim plankton from the water.
Example: Northern Shoveller (Anas clypeata)
Birds that feed on insects
Warblers (family Sylviidae) and Old World flycatchers (family Muscicapidae) possess thin and pointed bills. Such bills are very suitable to catch small insects.
Example: Common tailorbird (Orthotomus sutorius)
Birds that feed on nectar
The bills of sunbirds (family Nectariniidae) are long, thin and curved downwards. This allows the bird to insert its bill into flowers and drink the nectar inside.
Example: Fork-tailed sunbird (Aethopyga christinae)
Birds that feed on seeds
Buntings or American sparrows (family Emberizidae) and Java Sparrows (family Estrildidae) have thick and conical bills, which are used to crack the hard outer shells to reach the seeds.
Example: White-rumped Munia (Lonchura striata)