Environments.

The previous module discussed the foods which birds eat and where they might find it. Another way of looking at birds is to focus on the environments in which they live and how they use them to find and take their food.

A broad-brush approach suggests that about one quarter the world's species can be placed as follows:-

  • Aerial environment - 8.4%
  • Aquatic environment - 10.2%
  • Terrestrial environment - 5.2%

This leaves the other three quarters which I place in:-

  • Arboreal Woodland and Forest - 31.2%
  • Bushes and Thickets - 22.5%
  • Seeds, Crops and Flowers - 22.5%

Environment / habitat groups.

  • Aerial environment - 8.4%
  • Aquatic environment - 10.2%
  • Terrestrial environment - 5.2%
  • Woodland and Forest - 31.2%
  • Bushes and Thickets - 22.5%
  • Seeds, Crops and Flowers - 22.5%

They can be further split into sub-groups as follows:-

Aerial (8.4%).

  • Birds of Prey, including Opportunistic Scavengers - 6.4%.
  • Aerial Insectivores - 2.0%.

Aquatic (10.2%).

  • Oceans, seas, coastal and shore regions - 4.6%.
  • Inland waters, wetlands, rivers, marshlands - 5.6%.

Terrestrial (5.2%).

  • Polar, mountainous areas, rocky hillsides - 0.7%.
  • Barren, sparsely vegetated land - 1.2%.
  • Heaths and hillsides - 3.3%.

Woodland and forest in general (18.9%).

  • Fruit and berry eaters - mainly tropical regions - 14.1%.
  • Coniferous and deciduous - seed and caterpillar eaters - 2.3%.
  • Nocturnal hunters - 1.2%.
  • Ground feeders - 1.3%.

Tree trunks, branches and foliage (12.3%).

  • Peckers, probers, creepers - 3.1%.
  • Branch-tip gleaners - 2.4%.
  • Foliage gleaners - 6.8%.

Bushes and low perches (11.3%).

  • Fly out, catch insects, return to perch - 5.6%.
  • Flushing feeders - 1.4%.
  • Fly down, snatch insects from ground, return to perch - 1.6%.
  • Fly down, take small mammal from ground, return and impale on spike - 2.7%.

Dense thickets and undergrowth (11.2%).

  • Low tangled undergrowth - 7.0%.
  • Forest leaf litter - 4.2%.

Seeds, crops and flowers (22.5%).

  • Seed eaters - 10.6%.
  • Nectar eaters - 8.0%.
  • Fields, habitation, cultivation - 3.9%.

Each group is summarised in the drop-down menus under Food Source. Clearly this grouping is subjective but the food source serves as a starting point in the assessment of the environment and habitat in which the birds are likely to be found.

I have to stress that grouping the birds of the world in this way causes me significant problems. Most birds, except those which have become flightless, fly and can be considered to occupy an aerial habitat. Similarly many birds are, at some time or another, seen on the ground or perched in trees so they could be said to occupy terrestrial or arboreal habitats respectively. The aquatic environment is perhaps the only one which can be covered by a more precise and meaningful habitat definition.

Nevertheless I have presented each of the above sub-groups because it allows me to assemble information about habitats and niches in a way which I find useful in the Bird Groups module which follows.