As she arrived at the bushes, she started preparing a refuge. Pieces of herbaceous plants and dried leaves were lodged steadily. Soon enough, she was joined by her mate. Putting strips of plastic and twigs together took weeks to finish.
The first egg was laid on the nest. One more egg was laid the next day. The mother was keen on incubating both eggs. It lasted a few days.
After some time, one four-day-old chick was gaping to be fed. The other would crane its neck up. Both parents were tirelessly looking for food, and once one meal was delivered, they flew off to find more.
Then there was a low, distant hum and it grew louder like a rattling sound. The trees began to fall in different directions, and the young birds were startled by the noise. Because of the perceived danger, they thought of flying, but they were too young.
Chirp! Chirp!
The parents came back shocked. One hatchling was lying on the ground. Trees were falling everywhere but they must find the other one, so they kept on looking. In despair, the female bird cried and left after all of the chaos around her.
Not everybody will hear her. No one would know that she just lost her child. Everyone is juggling with paperwork and deadlines. Someone’s got to pay rent, find a job, and feed a family. Why would they ever notice a bird’s agony?
Do you know that they are warm-blooded animals and have a four-chambered heart, just like us? A similarity often overlooked. But birds don’t really look like us—they have feathers. They lay eggs. Definitely, not us! Unless you lay eggs, too.
When a bird’s natural habitat is altered by urbanization, it can cause some dramatic problems. There is noise from road traffic and construction machinery. Obviously, there is plastic consumption from fast-moving consumer goods. Concrete absorbs more heat, causing warmer temperatures, an “urban heat island effect.” Excessive artificial lights installed in the city cause light pollution.
The pressure of living in the city takes a toll on some birds, while others cope well with the new conditions. Noise may disturb communication between songbirds and affect their breeding productivity¹, causing a decline in their abundance². Chinese bulbuls can use plastics as nesting material, showing adjustment to the materials available in the city³. While birds from temperate regions can benefit from urban heating⁴, urban heat islands can cause heat stress and dehydration to some birds in the tropics⁵. Changes to the behavioral patterns of nocturnally migrating birds due to urban lights can also be energetically expensive⁶.
Aside from altering bird behavior, urbanization increases habitat fragmentation. Habitat fragmentation is when a large expanse of habitat is converted into smaller, isolated patches. After the transformation, the properties of the remaining habitat are also changed⁷. Habitat fragmentation is estimated to be responsible for habitat degradation and 75% of terrestrial biodiversity loss⁸.
Habitat fragmentation also reduces ecological connectivity. It impedes the movement of species, as well as the flow of natural processes⁹. Connectivity loss will limit birds’ dispersal abilities, affecting their breeding activities and reproductive success¹⁰. Birds are also seed dispersal agents that maintain plant communities, and the loss of connectivity may eventually result in loss of green space¹¹.
Loss of connectivity highlights the importance of identifying potential safety passages known as “ecological corridors.” These ecological corridors (see figure below) provide links to restore and maintain ecological connectivity to areas that have become isolated due to fragmentation. They are not a substitute for protected areas, but should nonetheless be established to maintain connectivity between isolated patches¹².
Recently, researchers have deduced effective parameters for identifying and designing potential ecological corridors by using target species like birds. Birds are mobile organisms that can provide links or flow between fragmented habitats. Their likelihood or unwillingness to move through a land cover can be mapped and used in connectivity analysis¹⁴.
Some planners use patch size as a basis in identifying priority corridors for birds like Maya because these birds prefer larger patches as nesting, foraging, and breeding sites, while corridors for Bulbul are based on vegetation types since their nesting and breeding sites are located near urban gardens and food resources¹⁵.
Tigayon, Kalibo, Aklan
8 April 2021 11:32 AM
Nikon D3200 ISO1600, 300mm, f/5.06 1/250
These birds are commonly found in different parts of Southeast Asia. They are well adapted in the city but prefer densely vegetated areas. They are mostly recognized by their bright yellow vent—hence their name, Yellow-vented Bulbuls.
Bulbuls are frugivorous. They can swallow whole fruits and berries of 8-10 millimeters. They adjust their nesting and breeding sites near food resources and make their untidy nests in urban gardens and trees near wetland and farmland. For bulbuls, the important parameter for designing ecological networks is the vegetation type.¹⁶
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| Eurasian tree sparrow (Passer montanus) Tigayon, Kalibo, Aklan 22 May 2021 04:43 PM Nikon D3200 ISO400, 85mm, f/4.0, 1/400 They are commonly called Maya in most parts of our country. Although these birds are found almost everywhere in the Philippines, they are believed to be introduced by the Spaniards. |
Apart from patch size and vegetation type, patch distance is also used. Planners identify how far a bird can disperse a seed from one place to another, or move to breed or nest. Both Maya and Bulbul have a dispersal capability of 1 km. Their seed dispersal ability, breeding, and nesting behavior depend on many factors. For example, they are most likely to choose shorter pathways near food sites, to spend less time traveling and avoid fewer hazards¹⁸.
Patch distance, size, and vegetation are some of the parameters that represent how birds behave in a habitat. These are measured to identify potential corridors. Visualizing them on a larger scale like in an urban landscape can be very difficult.
To resolve this issue, urban planners use models to predict how these birds might “move” between patch sites. In modeling, they use software applications like Circuitscape to map and estimate these movements by incorporating parameters like patch size and vegetation types. The model can also predict “which route” will facilitate greater movements for birds by calculating the distance traversed by birds between habitat patches¹⁹.
Today, most urban planners are developing better models to further understand how ecological connectivity works in different habitats. Each habitat has a different set of species, vegetation, and size. Such variations seek to address different strategic plans that will effectively establish and implement appropriate ecological corridors, especially in areas that require protection and conservation management that is greatly affected by habitat fragmentation.
These corridors could just be a small pathway of bushes and trees that may seem of no value to you—but they are important to those birds that are impacted by large-scale clearing operations that build residential houses, roadways, power plants, and malls. Those birds constantly move to look for resources — find shelter, food, and nesting grounds. A little bit of habitat will give them enough space to move around but if we continuously block their way, we could end up losing their population. Just like how the female bird lost both her children.
About the Author: Jessica Carlos grew up in Taguig and now lives in Kalibo. In her spare time, she enjoys taking photographs and watercolor painting as creative pursuits.
Literature Cited:
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