Climate
Change

Climate change is one of the biggest threats to biodiversity in the world.

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We are currently in the sixth mass extinction, with thousands of species heading towards extinction due to anthropogenic (human-mediated) climate change. 

How does it change our world? 

Climate change is leading to an increase in the impact, frequency, and duration of extreme weather events like floods, droughts, hurricanes, and heatwaves which can have catastrophic effects on our wildlife and plant species, as they are unable to adapt to the extreme and changing conditions.

 

Even in the era of COVID-19, where many people struggled with health, both mental and physical, many took solace in their dawn chorus at home. Though you would think the pandemic may lessen the hard-hitting impact of a warming climate, climate change is still perceived as a much bigger threat to the future than COVID-19, with people in the UK and US citing it as a constant worry.

 

Songbirds have displayed changes in reproductive success and migration which have been attributed to the changing climate, so we offer insight and tips to reduce your carbon footprint and ease the burden. 

Changes to breeding and food availability 

Songbirds are the “Canary in the Coalmine” for the health of our natural environment.  They show some of the first effects when something is wrong (or right). 

 

Delicate little bodies and strict, season-linked breeding activities mean they are the visible sign that we need to make changes for the better.

 

Warmer weather often signals that it is springtime, causing birds to start preparing for the breeding season and laying eggs. Reproduction is expertly timed to coincide with the emergence of prey like flying insects or caterpillars, to provide chicks with plentiful food for the best chances of success.

 

However, warming climates have caused birds to start laying earlier, often around 2 weeks earlier than they historically laid. Research conducted in the US showed a third of species examined advanced their laying dates by over 2 weeks. 

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Experiments on blue tits have shown for every +1°C, there is stronger selection by blue tits to lay earlier, and the number of fledglings was negatively correlated with the number of very hot days during the nestling phase. 

 

Extreme weather events and even small fluctuations in temperature of ~1.5°C influence the survival of chicks, with a decrease in the size and weight of offspring that do survive.

 

Over 57% of recorded occurrences of extreme weather in a 2018 global study showed that birds have a negative response to these extreme events, with reduced reproductive success, survival and in some cases huge population declines. 

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Very dry springs followed by hot, dry summers, mean reduced prey and drier ground for plants and insect life, impacting species including the thrush family, that rely on soil invertebrates for food and mud for nests.

 

A 2004 study on song thrushes found the summer weight of both adults and chicks were negatively related with dry soils; adults would have to go further to find food causing increased risk of predation and reduced condition.

 

The additional loss of favourable habitat such as damp ditches and hedgerows reduced food sources and increased chances of predation.

 

Similar issues beset the reed bunting where winter survival rates are probably the main cause of their decline. The widespread use of herbicides has reduced availability of the small weed seeds these buntings feed on, leaving them under nourished and no longer able to unable to survive severe cold snaps and the long dry winters which are becoming a feature of the UK as climate change progresses.  

Changes to migration 

Studies at the end of the 20th century into temporal migration, showed that birds had already found traditional summer breeding sites too warm and moved to the slightly cooler north by an average of 12 miles.

 

This has continued and you may well have noticed this with the change in species nesting and breeding in your local area over the years.

 

Poor weather during migration can cause an early or late arrival, but some species have shown a continuing shift to migrating earlier and earlier such as the house martin which arrived almost 6 days earlier in a 20-year period due to spring air temperatures. 

 

Studies have shown that birds that arrive early may also stay longer, with a recent 2020 study on reed warblers finding that breeding periods of females have extended by 2 weeks and produce 75% more fledglings compared to the 1980s. The proportion of females raising second broods increased from 2.7% to 23.6% between the first and the second study period while the share of females that did not produce any young annually decreased from 48.1% to 15.5%. The higher offspring production in recent years was related to more successfully fledged broods and an earlier start of breeding, which secured more time to re-nest. 

Adversely, Swifts also arrive early and could benefit from a longer breeding season but have been found to suffer terribly due to extreme spring weather events.

 

This is probably due to their morphology, being less able than other species to bounce back.  A 2006 study found that inclement weather during breeding season also caused a marked reduction in breeding success in the following year.  

It is not only the weather during summer breeding which can cause problems. Autumn and winter are becoming drier and colder in many over-wintering sites.  This negatively effects the abundance of food and suitable habitat available. 

 

A 2017 study found reed warbler adult survival was negatively impacted by these conditions and a 2016 study found Meadow pipits and Chiffchaffs were being squeezed into smaller and smaller winter sites and may have to adapt and evolve and travel further to find suitable habitat in new locations.

 

Interestingly, a common theme in the studies points to winter survival of adults as one of the main indicators of species population changes.  A 2007 study on 10 UK resident species concluded “strong effects of weather on the survival rates of national bird populations” while a 2021 study found that wintering bird communities are tracking climate change faster than breeding communities – birds are not just biodiversity indicators, but also climate indicators. 

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A glimmer of hope; it’s not too late! 

While this can sound all doom and gloom, it’s not too late to act. If we all do our bit, we can make real and positive change to our planet. The UK government has pledged to work towards being net zero by 2050, where we limit our carbon emissions as much as possible so that the emissions produced are removed by natural means (forests) or carbon capture technology. SBS has five top tips to reduce your carbon footprint: 

  1. Walk, cycle, or use public transport wherever possible. 

  2. Turn off lights when not in use and unplug your electronics when you don’t need them. 

  3. Recycle, reuse, reduce! Try and recycle as much as you can, take good care of your clothes so that they don’t need replacing as often and choose refillable water bottles rather than plastic! 

  4. Try opting for local or seasonal products when at the grocery store. Why not support your local farm shops? 

  5. Switch your energy provider to one that provides electricity from renewable energy like wind, hydroelectricity or solar. 

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To help our birds cope with the challenges climate change provides, we also have some tips for making their life easier, with our top five below. 

  1. Provide clean water throughout the year. In the summer months we are experiencing drier spells, and in winter freshwater freezes, so check on your water baths daily. 

  2. Provide fresh food in clean feeders throughout the year. Birds can struggle to find food, especially in the winter months so providing a haven in your garden is so important. 

  3. Encourage biodiversity. Plant insect-friendly flowers and plants and forget the pesticides to allow insect life to flourish. 

  4. Create a bird-friendly garden. Provide shelter, water, natural nesting materials and food options such as berry bushes and seedheads. 

  5. Get others involved. Influence your friends and family to look out for songbirds in their gardens, support our work, donate and fundraise so that we can fund more research in ways to combat the decline of songbirds. 

What are we doing to lower our carbon footprint? 

  • We have remote workers in our charity wherever possible to reduce travelling 

  • We have reduced our in-person meetings by using online technologies instead

  • We implemented an environmental policy for when travel is necessary and use public transport as much as possible 

  • We have reduced how much we print so that we use less paper in our office 

References

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Ceballos, G., Ehrlich, P.R., Dirzo, R. (2017) Biological annihilation via the ongoing sixth mass extinction signalled by vertebrate population losses and declines. PNAS. 114(30): https://doi.org/10.1073/pnas.1704949114  

 

Ceballos, G., Ehrlich, P.R., Raven, P.H. (2020) Vertebrates on the brink as indicators of biological annihilation and the sixth mass extinction. PNAS. 117(24): 13596-13602.  

 

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Crick, H.Q.P. (2004) The impact of climate change on birds. Ibis. 146: 48-56. 

 

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Evensen, D., Whitmarsh, L., Bartie, P., Devine-Wright, P., Dickie, J., Varley, A., Ryder, S., Mayer, A. (2021) Effect of “finite pool of worry” and COVID-19 on UK climate change perceptions. PNAS. 118(3): e2018936118. https://doi.org/10.1073/pnas.2018936118  

 

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Halupka, L., Borowiec, M., Neubauer, G., Halupka, K. (2020) Fitness consequences of longer breeding seasons of a migratory passerine under changing climatic conditions. Journal of animal ecology. 90: 1655-1665. 

 

Jiguet, F., Julliard, R., Thomas, C.D., Dehorter, O., Newson, S.E., Couvet, D. (2006) Thermal range predicts bird population resilience to extreme high temperatures. Ecology Letters. 9(12): 1321-1330. 

 

Lehikoinen, A., Lindström, A., Santangeli, A., Sirkiä, P.M., Brotons, L., Devictor, V., Elts, J., Foppen, R.P.B., Heldbjerg, H., Herrando, S., Herremans, M., Hudsdon, M.A.R., Jiguet, F., Johnston, A., Lorrilliere, R., Marjakangas, E-L., Michel, N.L., Moshøj, C.M., Nellis, R., Paquet, J-Y., Smith, A.C., Szép, T., van Turnhout, C. (2021) Wintering bird communities are tracking climate change faster than breeding communities. Journal of animal ecology. 90(5): 1085-1095.  

 

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