Bird Migration Changes Due To Climate Change

Nature tourism related to bird watching has been a growth market on an international level for several decades. There is also great interest in birding among visitors to nature parks and wildlife reserves.

The hobby of bird watching with its many thousands of active birding enthusiasts is a valuable contributor for the professional of ornithology (bird research). Bird watchers are often well equipped, with top-of-the-line binoculars, spotting scopes, GPS, camouflaged tents, and extensive knowledge of bird species, and their occurrence in certain areas.

Bird watchers are the first to notice that the bird population and the distribution of many species are changing. Just looking out into your backyard, you have probably noticed that some species are no longer there.

How climate change affects bird populations?

Breeding birds need a specific season to breed, so timing is crucial for them. Most species have a little window of opportunity to obtain the food they require to feed their young. It is especially true after the wealth of spring has arrived. It happens because other bird species also swoop in to compete. Interestingly, according to a new study, birds are breeding earlier than expected as the climate keeps on getting warmer. In addition to breeding earlier, their breeding windows are narrowing as well. The breeding windows have been reduced to 4 to 5 days in certain cases. Thus, this might lead to greater food competition, putting many bird populations at risk.

Birds usually reproduce in response to signs signaling the start of spring so that their young hatch when food sources are plentiful. However, many species have been pushed to reproduce earlier in the year as a result of global warming. We can observe this effect more noticeably at higher latitudes. It is because the temperatures are rising there faster than near the equator. However, few studies have looked at how climate change impacts the length of breeding windows, which are used to track the number of chicks born each year as well as population trends.

The implications of climate change on birds

It is true that climate change is already impacting the behavior, ranges, and population dynamics of birds. Furthermore, most of the bird species are already suffering negative consequences. It is predicted that the consequences of sudden climate changes can endanger a lot of bird species.

Disturbance in egg-laying time

Climate change has accelerated the egg-laying process of birds. For example, birds are laying eggs 6.6 days sooner per decade on average. Tree Swallows in North America are nesting up to 9 days sooner than they were 30 years ago. It has been associated with the rising average spring temperatures.

On the other hand, the breeding date of Common Murre has been extended by 24 days per decade in North America.

A significant change in migration times

Birds are beginning to migrate early in the spring. The researcher examined 63 years of data to find insights about the 96 species of bird migrants in Canada. They discovered that 27 species have drastically changed their arrival dates at their usual spots. In addition, most of the bird species arriver earlier than expected, primarily due to warmer temperatures during the spring season.

On the other hand, people have noticed that some birds have also delayed the departures.  A study of 13 species of the North American region revealed that six species had delayed their departure mainly because of global warming. More alarmingly, some European birds are simply unable to migrate at all.

A variation in bird’s environment and their behavior

You may not know, but the life cycle and behavior of a bird are influenced by environmental cues. A prime example of this is the change of a season. Problems start to emerge when birds can’t modify their behavior as fast as the changes in their environment. For example, a change in breeding time and prey availability.

More importantly, long-distance migrants are especially more vulnerable to these mismatches. Consequently, it has become harder for them to predict what conditions will be like at their next destination. For example, the northern breeding areas of wood-warblers are getting early springs, but we are waiting to see the North American wood-warblers migrate earlier from their usual breeding area. Consequently, it may lead to late arrival, and they may face a shortage of food at their breeding area.

A great disruption in the distribution of bird communities

Many experts believe that global warming has the potential to disrupt all of the bird communities. It is possible birds can no longer find their food source. As a result, the unaccustomed birds may face new challenges in the form of unknown parasites and prey.

For example, mosquitoes are increasingly peaking earlier in the spring in the northern Hudson Bay region. We have not seen any changes in the habits of Thick-billed Murres. Consequently, they are suffering egg loss and a high mortality rate.

Moreover, there is a chance that some parts of Southern Ontario may have less than 14 species of warblers in the coming years. So, it may lead to an upsurge in forest pests.

Variations in the food web

The impact of changing climate on one species can be felt across the food web. As a result, it may affect all of the organisms linked with that particular food chain. For example, there are many complications in the polar bear’s food web. Increasing loss of sea ice has direct effects on the polar bear population. The problem is further aggravated by the negative effects on the food web. Usually, there is an abundance of ice algae. This type of algae normally flourishes in nutrient-rich pockets in the ice. Thus, a decrease in sea ice leads to a direct and linear decline of ice algae. Most of the zooplanktons use these algae as a food source. Later, these organisms were used as a food source by Arctic cod. The Arctic cod is important in the food chain because they are the primary source of nutrition for many marine mammals. It may surprise you, but seals also use these organisms as a food source. Polar bears are known to devour seals. As a result, ice algae decreases may lead to polar bear population declines.

Changes in buffer capacity and threshold limits of ecosystem

Extreme occurrences, including sudden wildfires, floods, and lack of water, can be mitigated to some extent by ecosystems. However, the mitigation capacity has been negatively affected by climate change. Thus, it puts the birds at are greater risk of damage. You can also take examples of how coral reefs are always there to provide protection to the coastal ecosystems from storm surges and other extreme events.

Sometimes a threshold, or “tipping point,” is crossed, and as a result, ecosystem change occurs quickly and irrevocably. The United States’ Prairie Pothole Region is also on the verge of crossing thresholds. A wide region of small, shallow lakes known as “prairie potholes” or “playa lakes” makes up this habitat. The majority of North American duck species rely on these wetlands for nesting. In the past, the pothole region has endured brief droughts. A continuously warmer, drier future may result in a tipping point. It means we may witness a severe decline in the prairie potholes. They are mostly known as a habitat of house waterfowl. As a result, they provide amazing hunting and tourism opportunities.

Possibility of extinction of bird species

Birds with limited ranges, small populations, and low capacity to migrate from their range or those currently facing conservation issues are the most vulnerable to climate change.

Migratory birds have been at the top of the list of those affected by the sudden and severe changes in the climate. The primary reason for it is that they always rely on multiple habitats for their survival.

On the other hand, Arctic birds are particularly susceptible since the region is quickly warming. It may surprise you, but at least 85 percent of the world’s bird species breed there. It means huge swaths of habitat will be destroyed. It also includes tundra and sea ice. Ivory Gulls, which forage near sea ice, may suffer severe effects if sea ice retreats. The data of the last two decades show that the number of Ivory Gulls in Canada has decreased by 90%.

Potential effects of climate change on bird watching in U.S. national parks

Birds are well-protected in American national parks from a variety of invasive and ecological concerns. However, the influence of climate change on park bird populations is relatively unknown.

Consider the dramatic lament of the Common Loon for a time. Or the Mountain Bluebird’s warble or the Hermit Thrush’s song. We have named only a few of the famous birds that may become extinct in the next 30 years in Washington. Most of the bird species that you are used to watching in U.S. national parks are most likely to shift as our climate changes. If carbon emissions continue at their current rate, you will not be able to watch about 1/4th of the bird species by 2050.

The new study by Audubon emphasizes the necessity of preserving climate “strongholds,” such as those found on public lands, where a bird species is believed to have the highest chance of surviving climate change.

Some birds in the United States have already changed their behavior and range as a result of climate change-related changes in temperature and rainfall. Audubon experts established “climate suitability” for each of North America’s bird species (>500) in this study. They used parameters like the range of temperatures, level of precipitation, and variations in seasons that are required for a particular bird’s survival.  The next predicted all of the bird’s temperature appropriateness by using the greenhouse-gas emissions pathways.

Uninhabitable climate conditions for birds

According to the analysis, over two-thirds of North American bird species — 389 out of 604 — are at risk of suffering “unlivable climate conditions throughout most of their existing ranges by 2080” if global temperatures continue to rise by 3 degrees Celsius.

Furthermore, the Audubon Society has identified ten birds in Will County that are extremely sensitive to climate change. In addition, there are 32 others that are somewhat vulnerable. There are many birds, but scarlet tanager, eastern towhee, bobolink, and cerulean warbler are most noticeable in the list of most vulnerable birds. The Canada geese, sandhill crane, American robin, and indigo bunting are among the moderately susceptible birds.

In the face of rising global temperatures, not all birds have such bleak prospects. According to the report, several local species — a total of 32 — are rated low-vulnerable to climate change. The bald eagle and black-capped chickadee are among them.

The wild turkey and northern cardinal are among the 54 bird species categorized as stable.

A continuous disappearance

Most of the birds migrate from one area to another in response to climate change. However, our climate is changing at an unprecedented rate. According to the Audubon Society, the change is more than 20 times faster than any other time in the past 2 million years.

As the temperature rises, the natural range of each bird species fluctuates, with some species losing range, others gaining, and others remaining steady. The extent to which a species’ native range is lost depends on how much global temperatures climb. According to the Audubon Society, loss of range can be damaging or even catastrophic for some species.

Consider the great grey owl, which may be found mostly in the forests of Canada, Alaska, and, to a lesser extent, tiny areas of the northwest United States. The owls’ range is shrinking as the temperature rises. According to the study, if the Earth’s temperature rose by 1.5 degrees Celsius, it would lose more than half of its present range. Nearly all of the owls’ current summer range — 97 percent to be exact — would be rendered uninhabitable if the temperature rose 3 degrees Celsius.

Climate change not only causes them to lose their natural range but also poses other threats. According to the Audubon Society, as the Earth warms, many more birds will be affected by escalating and more severe weather events. More wildfires, droughts, heat waves, torrential rains and floods, and false springs are among the weather threats. Sea levels are expected to increase as a result of rising global temperatures, eating land near the coasts. Furthermore, as a result of climate change, more land will be urbanized and converted to agricultural use, displacing critical bird habitats.

Conclusion

All of the birds have their own set of features that help them survive. Birds may struggle to adjust quickly enough to remain within their natural range of climatic conditions in their dwelling environment become too hot or cold, too rainy or too dry as a result of climate change.

Climate change has been demonstrated to influence birds both directly and indirectly. Bird distributions are strongly linked to both winter and summer temperatures. The increased temperature may have a direct impact on birds by pushing them to expend more energy for thermoregulation.

The results are clear: birds urgently require our assistance to survive. In addition, bird-watching activity can help to boost the pandemic-stricken economy.

More to read:

Climate warming changes bird migration timing and body size
https://wildlife.org/climate-warming-changes-bird-migration-timing-and-body-size/

Birds Are Migrating Earlier Because of Warming
https://www.scientificamerican.com/article/millions-of-birds-are-migrating-earlier-because-of-warming/

The impacts of climate change on the annual cycles of birds
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2781852/

Climate change could overturn bird migration
https://www.nature.com/articles/s41598-019-54228-5