Symbiotic Relationship Between Birds and Trees

Greater Goldenback woodpecker in action at the Poomaale Estate, Coorg.

Picture a bird without a tree. Sounds strange right? 

However, we watch this picture almost every day. Modern developments have made other (treeless) sights of birds more familiar. Pigeons bickering over chajjas or gathering in large groups on sidewalks (uncannily human-like!). Crows sitting on electric wires. Bee-eaters perched on cloth ropes. Though these are more frequently encountered visuals for urban dwellers, the mental pictures of birds always have a tree in the frame. We belong to nature and have instincts just like other beings of nature. So, no matter what pictures modern developments show, we know that a tree is where a bird always goes.

The Tree of Life

It is a fact well known that birds depend on trees for their life. From birth to reproduction, trees are an important part of birds’ lifecycles. Young ones (nestlings) are kept safe by the mother until they can fly. The nest itself is built from elements of the tree – twigs and fallen leaves. Throughout their life, and especially during growth, trees provide birds with food – berries, buds, seeds, nectar from flowers and much more. Birds often hide in tree holes and crevices, even mate and nest there, for it provides them with quiet safe space and often even insects to feed on. Even some insects that trees host (like grasshoppers, beetles, crickets, worms and ants) become the food for birds. Some birds like to build nests that hang from tree branches as well (think pendulous nest birds). Branches, leaves, twigs, fruits, trunks – there is no end to the list of favours a tree provides to a bird!

While a tree’s importance in a bird’s life is incomparable, is the reverse true too? 

Is the relationship between birds and trees one-sided or mutualistic? And if it is, in what ways do birds help trees? Let’s find out.

Birds Help Trees Just The Same

One of the most important acts of service a bird does for a tree is seed dispersal. When a bird eats the fruit from a tree, the seed is often undigested and is dispelled in the bird’s faeces. This way, the seeds from a tree land in a different place from itself. Now you may think, what’s wrong is a tree’s seed falls close to it and grows right there? Well, it may end up competing with the parent tree for nourishment, belonging to the same species. Therefore birds (among other creatures like the Asian palm civets, monkeys and more) play an important role in scattering the seeds of a tree, forming its presence far and wide and improving biodiversity.

Bird droppings also become a source of nutrients to the soil and the ecosystem it holds. By eating insects on and around trees, they control the insect population and dismiss and protect the trees from pest infestation. Weeds, unwanted wild plants that suck the nutrients of plants, are also consumed by some weed-eating birds like sparrows, crows and blackbirds.

A lesser-known benefit that birds provide trees is pollination. While pollination is a more specialised activity taken up by butterflies (and oftentimes moths), birds help to a considerable extent too. Some birds (including the hummingbird and sunbirds) consume the nectar from bright-coloured, strong-scented flowers (like hibiscus and parijatha), and in the process, end up carrying pollen. When they flock from flower to flower or tree to tree, they disperse the pollen to other plants helping plants to fertilise, reproduce and evolve.

The mutualism between birds and trees is exceedingly close-knit and complex. It has shaped the lifestyles of many birds (like the woodpecker, pecking away at the tree trunk for insects and worms). It has made creatures evolve to camouflage themselves with the tree (owls are nature’s best camouflaging species!). And this is just the tip, and the depths are being explored by naturalists worldwide.

What Kinds of Trees Invite Birds to their Ecosystem?

The considerations of birds when selecting a tree are quite simple. Shelter, protection from threats and food for nutrition. Three types of trees are most commonly preferred by them. 

Broad-leaved, dense foliage deciduous trees provide a great nesting area for birds. The thick branches and big leaves allow birds to find many strategic spots on the tree where they can hide from predators, mate and care for their nestlings. These trees often also provide some sort of food to the birds in the form of fruits or insects. When the leaves shed in fall, the birds use them to build nests by the time spring arrives. However, for winters, conifers are preferred by birds as they can withstand extreme cold and heavy snowfall. Fruit-bearing trees and undoubtedly the more favourable choice. They provide flowers for nectar and fruits which also attract many insects to the tree – an additional source of food for birds.

However, choosing a tree for planting in your yard or food forest needs to be a conscious decision. Trees are complex ecosystems in themselves and house many other living organisms besides birds. A deciduous tree in a desert does not survive and a banyan tree in Scandinavia does not thrive. Therefore, planting native trees should always be the first and the most important option. Not only does the regional soil support native trees, but the trees also give back nutrients that strengthen soil health. Even local birds are more familiar with native trees and know their way around those ecosystems. In every way, native species work in favour of the environment, taking less from the surroundings and giving more.