Chiswick wildlife – Birds

What’s happening at the birdfeeder?

Guest blog by Jo Gilbert, WildChiswick 

A lot more than you think you see! A fascinating and informative talk by Mike Toms from the British Trust of Ornithology (BTO), hosted by WildChiswick, revealed some facts that may surprise you.

BTO is one of those fantastic British institutions that has been around many years and without which we would know very little about our native birds and migratory visitors. BTO and their staff have been studying birds since the 1930s and at present have over 60,000 volunteers on the ground helping them with their research.

With so much data at their fingertips BTO can track changes in avian behaviour and reasons for any change can be investigated.

Mike spoke to us about why gardens are good for our birds. It appears that your garden is very important for our feathered friends, but they still take time out in the countryside as well.

In Britain, we love our birds. We spend £200 million a year on food to feed them. Other than the attraction of the food with which we supplement our birds’ diet, they are also attracted to gardens by water and the presence of trees, either in the garden, or nearby.

One garden alone is not enough. The importance of our gardens is that together they can create a green space, so it is collectively, that our gardens are important. If you look at a map of London, the area is quite green, and this is due to our gardens. The greener and more wildlife friendly we can keep our gardens then the more birds (and other wildlife) are likely to visit and flourish.

Image above: Robin on a fork; photograph Tommy Holden for the British Trust of Ornithology

Our gardens are supplemental for our birds. They are aware that food is there when they need it, yet many of them will eat wild foods from the surrounding countryside before moving into our suburban and urban areas.

Not all species find breeding in our gardens as suitable as the countryside either. A good example of this is the long-tailed tit. BTO Garden Watch data shows that this species will be in our gardens through the winter and autumn yet disappear during the summer months when they breed.

Robins too, find the countryside more attractive for breeding. More robins are found in the countryside than suburban and then urban environments. Of course, some of us are lucky to have birds breed in our gardens, not every bird stays in the countryside, but the preference remains.

In the suburban/urban environment there are pros and cons for our birds. The temperature stays warmer than out in the countryside and combined with global warming, migratory birds are staying longer on our shores.

Supplemental feeding is proving to be important for birds whose natural foods are being reduced in the countryside due to changes in agricultural methods. Wood pigeons are much more common in our gardens than previously, and they do tend to stay all year round – one species that is quite happy to breed in towns.

The beautiful goldfinch is another bird which now visits our gardens more often. This is due our feed mixes now containing a wider variety of seeds than in previous decades. This is proving a good supplement for a bird that is finding its food sources much rarer as wildflowers disappear from the countryside.

Birds visiting urban environments show changes in behaviour. Some species are beginning to show bold traits.  Blue tits for example are usually the winners on the bird feeder.  Shyer birds may miss out on the best of the daily meal.

You may have heard robins singing at night. This is not due to the street lighting as first thought but is because they can be heard at night by other robins when it is quieter. Birds need to be heard to find a mate and for young chicks to call out and be heard by their mothers. House Sparrows, for example, breed less in noisy environments. Blackbirds also change their pitch and drop notes from their call when the environment is noisy, so they can still be heard.

It appears that like some humans, birds can suffer from stress in the urban environment.  Research on Blackbirds show that those in urban environments suffer from genetic damage. Chromosomes are protected by telomeres which sit at the end of each chromosome. In urban blackbirds these are shorter than those in the countryside. This means they may die earlier consequently. However, it is believed that the benefits to be found in the urban environment outweigh the possible risk of an earlier death.

A more pressing cause of death for our birds is disease. Green finches are a good example of this. As a species they were stable from 1996 until 2005. From 2006 onwards there was clearly a steep decline in numbers. It was found that this was due to a protozoan parasite called Trichomonosis. This is normally found in aviary birds such as doves, pheasants and pigeons. It is believed the disease was spread via bird feeders as wood pigeons began to visit urban sites more frequently.

Unfortunately, a quarter of our green finches were lost, and they are struggling to regain their numbers. Some of you may have noticed a reduction in our blackbirds this year. I certainly have, and several people have asked me the cause. BTO has also noticed this decline through their data collection this year.  The decline is quite prominent in the London Area. BTO are of the belief that this is also caused by disease, and they will be sharing their finding shortly.

Images above: Jay bird (left); photograph Mark Lawson; Blackbird photograph Edmund Fellowes for the British Trust of Ornithology

BTO say that overall feeding and taking care of our birds in the urban environment is a good thing. Mike recommends we look at how different species use our gardens. He recommends sunflower hearts and seed mixes for our urban bird feeders. He suggests looking at where to feed birds.

For example, birds such as wrens and robins prefer to be ground feeders. They feel safer amongst shrubbery. Look at what you grow in your garden. Plant a tree if you can. Shrubs and ground cover too. Shrubs with berries are also good for our birds.  Include water in your garden – a pond or bird bath. Clean your bird feeders regularly to help stop the spread of disease. If you see a bird looking lethargic on you bird feeder then clean the bird feeders straight away and do not put food out for another two weeks.

As mentioned already, most birds prefer the countryside or wooded areas for breeding. If you do want to encourage breeding, then put out bird boxes.  Mike suggests that again you think about what type of bird visits your garden as this will affect what kind of nesting box they will like. The box needs to be a reasonable so for a brood to hatch and grow in. The size of hole should be about 32mm for a sparrow and down to 26mm for a blue tit. Do not place next to a bird feeder, in the prevailing wind or where there is full sun. Find a bit of cover to put it amongst if you can.

Finally, Mike asked us to look at the food we are buying. Not all foods are equal with regard their impact on climate change. Some are imported from quite far abroad. I had a quick check online and found several British Grown bird food suppliers, so it is possible to buy British!

If you would like to join the BTO as a volunteer and contribute to their research, then please visit bto.org where you will find out how you can get on board.

WildChiswick is a local community group with the aim of creating more awareness of the wildlife around Chiswick and inspiring people to protect or enhance our urban wildlife habitats.  

wildchiswick.com

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