Our feathered friends are usually the first to experience changes in the environment and have for centuries been made use of as indicators for these changes. In old tradition, observing birds and knowing them was prestigious. They were, even then, used as important indicators. In many cultures, eagles, hawks and owls were considered an omen. Today, modern science continues this tradition of bird observations. Ironically, scientific research has even shown that the spotted owl is a portent indicator to changing conditions. Similarly, the presence of woodpeckers is indicative of great biodiversity in forests, and can be an effective tool for environmental management and planning.
What are some of the things that these birds might be able to tell us? For one, they make habitat quality known. An ecosystem can support a number of species and their presence can tell us how the habitat is doing. A specialised species will be the first to get affected by degradation to their ecosystem. Their presence or lack thereof could be a clear-cut sign of change. Birds are finely attuned to the weather as well; wind patterns, precipitation. All of it determines their own breeding, migrating and summering seasons.
Birds are also the first to get affected by pollution – the best example is in Rachel Carson’s ‘Silent Spring’, of birds affected by the incessant spraying of the insecticide DDT, which resulted in weaker egg shells and hence low reproduction rates of birds. The white backed vulture of South Asia has gone virtually extinct as not a single individual has been sighted in over a decade. This has been attributed to the use of a drug administered to livestock for healing – diclofenac. In addition, bird feathers and egg shells can be tested for pollutants that can be compared to those preserved in natural history museums. Birds have been good indicators for disease as well, such as during the spread of influenza in the US.
Birders are key to noticing things such as when birds nest now, compared to the past; earlier or later? That is clearly indicative of changing temperatures. Some species in particular have been noted to slowly shift their territories northwards. Audobon has discovered that 305 species of birds in the United States have moved about 35 miles north in a span of 40 years, which is a stupendous change in such a short amount of time in the ecological world. This means that they may be moving to more ‘desirable’ temperatures, indicative of sea level rises. Yet, what does this mean for habitat and species? Certain species are more finely adapted to their surroundings such as Allen’s hummingbird. How will these species thrive in new environments with greater threats from predators or greater competition from other birds over resources? Climate change as we all know, has become a real issue for most wildlife, it is altering everything and shrinking their habitats.
Yet, climate change isn’t the only thing that birds are pointing out to us. Speculation and subsequent research has indicated that migratory birds have been disoriented by electromagnetic waves produced by us humans through satellites, mobile phones etc. This ‘pollution’ scientist Mouritsen termed ‘electro-smog’. Birds have been known to collide into buildings and communication towers due to this confusion, resulting in many deaths. Without the earth’s natural magnetic fields, birds cannot tell the difference between North and South. Humans are now hindering the very existence of the species we rely on as important indicators of change. Acid rain has been another problem, and wood thrushes have been our source for this information. Their absence indicated that due to acid rain, the soil lacked calcium, on which earth worms survived and the birds fed on. The lack of this calcium too resulted in weaker egg shells and low reproductive rates. With rapid and consistent urbanisation, that not only means greater electromagnetic waves, but greater habitat fragmentation and pollution, who knows what more heinous impacts we will inflict on bird species? If they are disoriented in their usual behaviour, how will we make effective use of them as indicators? If the environments they exist in no longer substantially exist, how will we know they are behaving ‘as expected’. Do we wait for the non-resilient ones to die out? Any research we do then will only be erroneous and shall impact any future decisions we make.
All this doesn’t mean that species simply vanish, it has huge repercussions for ecology as birds provide major ecosystem services. Birds are prominent seed dispersers, such as seen in the case of the Whitepine tree in the United States which humans and most animals have come to increasingly rely on. The expansion of this forest relies on one single bird for reproduction. The Clark’s nutcracker (a close cousin to the crow) is the only bird that cracks pinecones open, and eats its seeds. Uneaten seeds are then left where trees can reproduce. Without this crucial bird, the forests of the Whitepine would cease to exist. By this simple process, the nutcracker provides for $11 billion in seed germination, if it were done by hand. Similarly, all birds help farmers and other businessmen with their business as the agriculture industry (and thus our staple foods) would cease to exist without pollination by the avian specimens. By ensuring the growth of forests, there is a prevention of soil erosion. They are natural pest controllers, devouring and annihilating insect infestations, ensuring the slow spread of disease – ducks are known to eat mosquitoes which could then reduce malaria, dengue etc. Scavenger birds such as the vulture, are paramount to sanitation and human health, especially in places such as India where cow slaughter is prohibited. More importantly, they are perfect indicators of environmental and ecosystem degradation.
What can we do for sustainable practices? For one we must mitigate the effects of global warming. Cities must be made sustainable, and there are positive indicators for the ability of cities to support biota; through the expansion of green rooftops. Though further research could tell us which species will thrive, will they breed successfully and how do we replicate their known habitats? We do not have any answer to these questions, it must be said that green roofs will provide cover and safety from predators, which offer good nesting and breeding grounds. Recent studies have indicated a positive relationship with bird populations and green roofs. These roofs have seemingly provided at least a habitat for the more common birds. Mallards, finches and thrushes have in fact been breeding on these rooftops. The protection of important ecosystems such as wetlands and salt marshes (which birds use especially during their migratory periods) is also paramount as it is there that sea level rises and ecosystem degradation is impacting first and foremost. If we are not careful and don’t act fast what will become of our environmental indicators?