Trinity College Dublin, Ecology and Evolution
For those of us with an interest in the natural world, Mute Swans (Cygnus olor) are a staple of urban wildlife in Dublin, present in many parks and along both canals. However, it has been 25 years since there has been any real assessment of the state of the Mute Swan population in the Dublin region (1). This has been a period of immense change in the urban landscape.
Mute Swan © Graham Prole
Early morning flights are a pain: nobody likes rolling out of bed at the crack of dawn. But if you’ve spent a few bleary-eyed mornings at airports, spare a thought for the local residents. Birds rely on their song to find a mate and keep intruders out of their territory: not an easy task when you’re competing with the roar of a 747 taking off at 290 km/h. Now, research by scientists in Spain and Germany has found that birds living near major airports sing earlier in the morning to avoid being drowned out by aircraft noise.
Researchers from the National Museum of Natural History in Madrid and Freie Universität in Berlin recorded the dawn chorus at sites around 5 major airports. As lead author, Dr. Diego Gil explained, “the idea came one day that I was taking a very early flight and when I arrived at the airport I heard blackbirds singing very early. I thought that perhaps they were trying to get their voices heard before the planes would start flying”. His hunch turned out to be correct.
The team found that many birds such as robins, blackbirds, cuckoos and blue tits that live near airports sing earlier than is normal for their species. Variation in light pollution and daylight length at each site did not affect the tweeting birds so it seems that noise pollution from the airports is the key factor. This shift in the birds’ normal behaviour appears to be an evolutionary response to the pressures of living in an environment dominated by humans. The research was published in Behavioural Ecology.
The birds start singing early in the morning before the airport is active so they are not simply responding to immediate noisy cues. Instead, they appear to have evolved over many generations to adapt their behaviour to deal with the very predictable high noise levels from airports (starting around 6am and increasing throughout the morning). This ties in with previous research which showed that robins are more likely to sing at night in noisy cities and blackbirds start to sing earlier in areas with high traffic noise. With individual planes generating noise four times louder than bird song, it’s easy to understand why birds have opted for a strategy of avoidance rather than competition with their airport neighbours.
Changing their singing behaviour could put energetic stresses on the birds. Whether you consider it a melodious wake-up call or a chattering irritation, the dawn chorus is actually a bragging competition. Birds sing to defend their territories (“keep out this is mine”) or else to attract mates (“I’m big and strong so let’s make babies”). Singing costs both time and energy and must be balanced with the need to go and find food. As Dr. Gil commented, “I would think that singing earlier than what is expected for a given species would modify the energy budget for the birds. Of course, it is possible that there is an optimal solution for this, a kind of plan B, and that birds manage to compensate for it, but it surely brings about a challenge.”
The next step will be to determine the consequences of earlier singing times for birds near airports. The researchers plan to study general activity patterns and feeding behaviour to see if the birds are physiologically affected by their shift in singing times.
So, the next time you grumble about getting up for an early flight, think of your feathered neighbours who have to rise for the early shift each morning to sing their wake up songs and beat the airport rush hour.
Author: Sive Finlay, @SiveFinlay
Image: Wikicommons
As part of an ongoing census of the birds of Trinity College, we surveyed their diversity just outside our door.
Authors
Trinity College Zoology Students
Photo Credit
Trinity College Zoology Students
From October onwards, when most of our resident wildlife is battening down the hatches to endure the impending bleak winter months, flocks of Brent Geese are very welcome visitors to Ireland. Their arduous journey to our shores is impressive for both its distance (approximately 3,000km from Arctic Canada) and the route taken: long-distance sea voyages punctuated by stop-overs in Greenland and Iceland before they reach Ireland. The necessity to escape harsh Arctic winters is very understandable. What’s not clear is why Brent geese undertake Atlantic crossings instead of following other geese species that journey south across the American continent. Whatever twist of evolutionary fate is responsible, there’s no doubt that we are lucky to receive annual visits from such intrepid voyagers.
I’m sure many Dublin residents would agree that sharing seaside walks with companiable small family groups of geese or witnessing one of the chattering fly-overs of a large flock undoubtedly brighten up an otherwise bleak winter’s day. However, a recent Irish Times article identified Brent Geese as the enemies of an unlikely foe; urban cyclists.
For more than 10 years, the S2S group has campaigned to create a continuous cycleway for 22km around Dublin Bay, running from Sandycove on the south side to Sutton on the north side which, if completed, would be Europe’s longest seafront promenade and urban cycle-path. The plan would be a great amenity for both recreational and commuter cyclists – you only have to travel along the coast road from Fairview to Howth to witness the popularity of the existing cycle path along the black banks. Just 8 km of the route remain to be completed, mostly on the south side and a single 4km stretch from Sandymount to Blackrock is particularly controversial.
The proposed route would cut through EU protected bird habitats and, in particular, affect an area of eel grass consumed by Brent Geese. The National Parks and Wildlife Service (NPWS) is also concerned about the impact of the cycle way on other bird species which reside in protected areas in Booterstown.
While I’m often wary of articles alluding to stereotypical views of “conservation hippies” thwarting sensible developments, in this case I have to agree with councillor Barry Ward that there must be a solution which “inconveniences rather than displaces” the geese. No development affecting protected habitats should be undertaken lightly. In particular, since the majority of Brent geese overwinter at just 10 sites, Birdwatch Ireland lists their conservation status as “medium concern”. However, with their current population seemingly in good health and the plethora of suitable habitat which Dublin Bay has to offer, it seems unlikely that an 8 metre wide seafront path would have a major impact on the goose population.
I’m well aware that if every development took the attitude of “there’s plenty of habitat elsewhere” then there would be no protected areas left. In addition, I must admit my vested interest in seeing the cyclepath completed – I’m a recreational (i.e. fair weather!) cyclist and live in Sutton so the availability of 22km of off-road cycling on my doorstep is a very attractive prospect. However, if you observe the behaviour of geese along the existing cycleway they seem to be remarkably unperturbed by adjacent human activity and continue to forage just below the boundary wall. Surely the same coexistent relationship between cyclists and geese could be forged south of the Liffey?
Despite including the S2S cycleway as part of their development plan councillor Barry Ward argues that management of the Dún Laoghaire Rathdown county council seems to be reluctant to develop the cycleway. Beyond the legitimate concern that the proposed cycleway would pass through a protected area, there seems to be no specific predictions or estimations that the development would have an adverse effect on the geese. Rather than an issue of cyclist vs. geese, perhaps this story is really a case of scape geese taking the blame for a council’s reluctance or inability to fund and implement a new development?
Author
Sive Finlay sfinlay[at]tcd.ie
Photo credit
wikimedia commons
At the launch of our recent college Green Week, Trinity College presented the final stages of its bid to secure the Green Flag Award. Part of the assessment comprised a summary of the plants and animals which, along with the rarefied species of Drama studientis and the Lesser Spotted Theoretical Physicist, contribute to campus biodiversity. Foxes were included in this list which surprised me since I had never come across one campus.
Happily though, last Friday evening one made an appearance just in time for the end of Green Week. Displaying the characteristic “boldness” of its habituation to city life and unperturbed by the passing cars, bikes, and rugby players, a large, healthy-looking fox trotted along the road beside me and into a small patch of scrubby bushes outside the Physics building. It must be a member of the den that resides in the Provost’s Garden – which received celebrity status in a recent Irish Times article. It’s intriguing to speculate whether the Trinity foxes cavort on the cricket pitch long after the last reveller has left the Pav on a Friday night? Similarly, I would love to know whether they are exclusive Trinity residents or do they dodge the shoppers on Grafton Street to visit their cousins in St. Stephen’s Green? Perhaps they also visit Merrion Square – pausing along the way to pay homage to some long lost relatives entombed inside display cases within the Natural History Museum.
Urban foxes have received some bad press recently after the rather gruesome story of the fox which bit off a baby’s finger in south east London. The RSPCA was quick to stress that, while truly horrific, this incident was extremely unusual. Despite their reputation for pilfering unguarded bins, foxes are usually quite shy and wary of coming too close to humans. However, in the wake of the London attack, Mayor Boris Johnson, labelled urban foxes as a “pest and a menace” and there were many calls for a large-scale culling operation to be instigated.
These emotive responses to an isolated incident should not be allowed to dictate future policy for dealing with urban foxes. In his recent New Scientist article, Stephen Harris points out that we are more likely to be attacked by pet dogs rather than foxes and culling programs simply don’t work since new animals just move in to fill vacated areas. In his view, it’s human rather than fox behaviours which give cause for concern. He argues that natural history programs which show cavalier presenters coming in to close contact with wild animals encourage people to seek unnatural and sometimes dangerous proximity with urban wildlife. For example, leaving food out in the garden to attract foxes can lead to some great sightings of these beautiful mammals but placing that food close to a house or near open windows or doors is just asking for trouble. Moreover, feeding foxes is a divisive issue in itself – is it akin to leaving food out for birds or does it equate to just attracting unwanted pests into our gardens? Personally, I have no issue with leaving out scraps but buying cat or dog food just for foxes seems excessive, especially when our untidy cities are veritable all you can eat buffets for these city slickers.
Whether you regard them as pest or surrogate pet, foe or friend, foxes are an inescapable feature of urban landscapes. With Trinity’s campus as their playground, who knows what the one I saw gets up to after dark?
Author
Sive Finlay: sfinlay[at]tcd.ie
Photo credit
wikimedia commons
Typically, when humans and wildlife meet it’s curtains for the latter. Think of all the megafaunal extinctions in the past and the mounting evidence that we’re responsible for an ongoing sixth mass extinction event. Aside from directed extermination we can change the environment over a very short time-scale to suit our needs and other lifeforms are often left playing catchup. This is especially true for plants and animals (microorganisms have such short turnovers that we don’t really impact them in this way); the plight of the blue swallow isn’t top of an industrialist’s list of priorities.
Despite these radical changes, some species have adapted to living in our towns and cities. This has piqued the interest of scientists and we’re now seeing the burgeoning field of urban ecology populated by urban ecologists. The amount of urban biodiversity is quite surprising and the adaptations of the flora and fauna comprising it equally so. Look at the previous post talking about birds lining their nests with material from discarded cigarette butts.
As civilization has developed we’ve become more aware of the value of nature, be it an intrinsic worth or a more practical value. So we can actively change our urban centres to accommodate more species if and when we choose. Sushinsky and colleagues asked how we should grow our cities in order to minimise their biodiversity impacts. Their conclusion was a more concentrated city plan would be better suited to avian diversity than a sprawling one. Certainly, it seems better for our cities to grow vertically rather than horizontally if we are to minimise humanity’s footprint. So, more New Yorks and fewer Los Angeles.
We can even provide supplementary food to animals. Fuller et al. showed that bird feeders can increase the abundance of birds and pointed out that up to a third of households in Australia, Europe and North America supply food for birds.
Then there are species that can prosper on our discards when it hasn’t been our intention to feed them in the first place. Badgers, foxes, raccoons, bears, the list goes on. All of them can make a living in an urban setting.
With more and more of us cramming ourselves into cities we should be aware that there are real benefits to interacting with nature. We feel psychologically better when there is more of the natural world around us.
To butcher Gordon Gecko, green is good.
Author
Adam Kane: kanead[at]tcd.ie
Photo credit
wikimedia commons