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Canary in a Coalmine: Birds as Environmental Indicators

Birds are excellent environmental indicators.

Credit: Keith Marshall / Flickr

Birds are our environmental barometers. Their sensitivity to changes in the environment make them good environmental indicators of any subtle changes that may be occurring.

Changes in nature often occur gradually over time. In many instances these changes go unnoticed, while the environment gradually spirals into a decline. When the impact of environmental change is finally detected, it is often too late to rectify the damage. However, by observing subtle changes in the behavior and population trends of certain animal groups, biologists are able to gain a clearer understanding of what is happening in the environment. Similarly, assessing biodiversity by monitoring, sampling and recording every species in an ecosystem would take a lot of time, money, and manpower. However, certain groups of animals can often be monitored to give an accurate picture of the state of the environment, as well as an estimate of biodiversity. Birds are good indicators of environmental change, as well as species richness, and are very often used as environmental indicators, for a number of reasons.

Birds occur in all types of habitats, everywhere in the world. They are highly visible, easy to monitor, and much research has been done on them. We therefore have a good understanding of their behavior, biology, and ecology, and there is a lot of information readily available to make historical comparisons. Birds are both sensitive and responsive to environmental change. They have representatives feeding on the broad spectrum of animal groups, and as top predators, they are particularly vulnerable to bioaccumulation of chemicals and toxins. Consequently, they provide an excellent baseline for monitoring environmental change.

Birds have been used as environmental indicators of environmental pollutants, including radiation, pesticides, heavy metals, PCBs, and other toxic chemicals. They are widely used to monitor air pollution, soil pollution, and freshwater pollution. They are also used for monitoring changes in marine fisheries stocks.

Birds are excellent indicators of climate change as their behavior and breeding patterns are in tune with natural and seasonal cycles, such as temperature, rainfall, flowering of plants, and upwelling events, which all influence food availability, breeding success, and timing of migration. Any disruptions or changes to these natural cycles, no matter how subtle, can affect the behavior and breeding success of birds that is indicative of broader environmental change.

Many migratory bird species have shown changes in departure and arrival times at breeding and wintering grounds. Changes in the timing of bird migration has been linked to climate related factors, such as temperature, wind, and ocean currents.

Seabirds are good environmental indicators of ocean productivity and prey availability. By monitoring the diet of seabirds, through non-lethal diet sampling techniques, biologists can determine shifts in prey regimes and availability, and correlate this to ocean conditions and climatic patterns. Seabirds and other marine predators, such as predatory fish, seals, dolphins, and whales, depend on krill, fish and squid for food. The availability of food in marine food webs is dependent on ocean productivity and the distribution of prey, which is determined largely by ocean temperature and upwelling events. Upwelling brings nutrient rich water up from the depths, while cold sea surface temperatures allow more carbon dioxide to be absorbed by the ocean. These two ingredients, together with sunshine, allow phytoplankton – the base of marine food webs – to flourish, creating a productive system. In order for marine birds and mammals to breed successfully, the timing of breeding needs to coincide with periods of high productivity. The timing of breeding, together with breeding success, survival, distribution and abundance of marine predators – including seabirds – are all factors that are influenced by climate change. By monitoring breeding patterns and reproductive success of seabirds, biologists are able to determine ocean productivity, and make fisheries management recommendations in an effort to prevent overfishing and a total collapse of fish stocks. It also helps them to anticipate changes in productivity in relation to a host of environmental parameters, including those associated with climate change.

Birds are good barometers of the state of the environment. Monitoring bird populations is important – it allows us to monitor subtle environmental changes that could potentially affect biodiversity, or have socio-economic implications. One thing is clear, if the birds are in trouble, something is amiss in the environment, and it could very well indicate that we may soon be in trouble too.

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