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The threats behind the plight of the puffin
Puffins are facing a perilous future. Population numbers have fallen sharply, and there are even fears the sea bird could be heading towards extinction within the next 100 years.

A much loved and enigmatic creature, puffins are easily identified by their wonderfully coloured beaks. They waddle around in a characterful fashion and make the strangest of noises. Their endearing features have been used as the symbol of children’s books, and to illustrate many stamps – but they are now also appearing on lists of endangered species.

On Britain’s Farne Islands, numbers have gone down 12% on average over just five years, with one island’s population falling by 42%.

The common puffin, named after its puffed-up swollen appearance (although its scientific name, Fratercula arctica, arises from its resemblance to a friar wearing robes) has an extensive range across the northern hemisphere, with breeding colonies from Norway to Newfoundland.

Around 90% of the global population is found in Europe, with 60% of the population breeding in Iceland (which is also home to a tradition which involves children rescuing young, wayward puffins – “pufflings” – and returning them to the safety of the sea). The UK is home to 10% of the global puffin population, breeding on many islands and mainland coastal areas.

Although there are around 450,000 puffins in the UK, the species is threatened with extinction due to their rapid and ongoing population decline. Recent surveys of the Farne Islands revealed that despite a steady increase over the previous 70 years, numbers have declined by as much as 42% over the past five years.

Unfortunately, we know very little about the ecology of the puffin outside the breeding season. Although the birds amass in large numbers to breed, they spend two-thirds of their life alone, out in the north Atlantic sea. Consequently, they are very difficult to monitor.

What’s causing the decline?
Firstly, although puffins live for a fairly long time (the oldest recorded so far reached the age of 34), their breeding population is limited to a small number of sites. They also have a low reproductive rate, laying just one egg a year, which makes them particularly vulnerable to adverse changes in the environment and means they can take a long while to recover from negative impacts.

They are also hunted – by humans and other animals. Smoked or dried puffin is considered a delicacy (or a flavouring for porridge) in some places, such as Iceland and the Faroe Islands. But although they were once over harvested by people, hunting is now maintained at a sustainable level.

During the breeding season, puffins nest in burrows on clifftops. Although this offers the nest protection from aerial predators, such as gulls, chicks and eggs are not safe from mammals, including weasels and foxes. On Lundy Island in the Bristol Channel, the population of puffins fell to just 10 pairs, but since the eradication of rats there, things are looking up. Nevertheless, the Arctic skua can be a particular problem as it steals food from adult puffins which is intended for their young.

Living on the open ocean makes the puffin highly susceptible to pollution such as oil spills. After the Torrey Canyon oil spill in 1967, the number of puffins breeding in France the following year decreased by a massive 85%.

The puffin feeds almost entirely on small fish, including sandeels, herring and capelin, which make up over 90% of the diet of pufflings.

The birds have a specialised beak with backwards facing spines, which prevents their prey (up to around 60 fish at a time) from falling out of their mouths when foraging. But in years where the main food source is low, many chicks starve to death.

Puffins have also suffered increased mortality from the rising frequency and intensity of extreme weather events associated with climate change. A recent succession of severe storms caused 54,000 seabirds, half of which were puffins, to be washed up along coasts. Starvation was cited as the main cause of death.

On a cliff edge
Sea temperatures have increased over the past 30 years, causing indirect effects on puffin survival. The rise in temperature decreases the abundance of plankton, which in turn leads to a reduction in the growth and survival of young sandeel and herring on which the puffins rely, particularly during the breeding season. Conditions in the North Sea are even causing some puffins to travel into the Atlantic, rather than the North Sea, in search of food – a perilous trek involving greater distances and different habitats.

It seems that a combination of factors are to blame for the decline in puffins, but the reduction in their food supply, particularly as a result of increased sea temperatures, appears to be the main culprit.

We need to continue monitoring puffins worldwide to better understand factors affecting populations. Hopefully, we can put measures in place to minimise pollution, reduce introduced predators and promote sustainable harvesting to try and ensure that the fate of this wonderful bird is not the same as that of the dodo.

Birds: we studied 4,000 ‘alien introductions’ to find out why some were successful
Species introduced by humans to areas where they don’t naturally occur are a worldwide problem. These “alien species” can cost a lot of money to deal with, and they’re the number one driver associated with recent extinctions worldwide. The rate at which new populations of alien species are establishing is increasing rapidly, and ideally we’d like to stop the process in its tracks.

But first we need to answer two key questions: firstly, what features of species make them good at becoming alien? For instance why has the Indian myna bird managed to establish itself across the world while its relative the crested myna has not? And, secondly, what is it that makes some locations more susceptible to aliens establishing there? While we have made progress in answering the first question, we haven’t done nearly so well with the second.

Myna birds are invasive pests in Australia. PapilionemK / shutterstock
The reason for this is that the environment is very complicated and so many elements of it might be important for an arriving alien species. For instance the climate at a new location is likely to matter, not just in absolute terms, but in how well it matches what the alien is used to back home. Climatic extremes may be as or more important than averages in this regard.

Which species are already present at the location is also likely to be important. Too many and the alien may get easily outcompeted or eaten, too few might mean there wasn’t enough food in the area. Again, the identity of the alien matters in these regards. Habitat will matter, as will the extent to which humans have modified it. Finally, all of these features of the location vary over space and time, and which species get introduced as aliens also is not random, all of which introduces a range of complications.

In collaboration with colleagues in Australia and the US, my research group set out to attempt a rigorous global analysis of why some locations are more susceptible to alien establishment. We first assembled a catalogue of more than 4,000 alien bird introductions, featuring everything from Australian magpies in New Zealand to Southeast Asian zebra doves in Hawaii.

We then overlaid it with information on features of the local environment, species traits, and how many individuals got introduced (important because small founding populations can easily fail by accident), and used complex statistical methods to assess the impacts of all these different factors.

Egyptian goose in Regent’s Park, London. First introduced on country estates, the birds have now lived in the UK for centuries. By Martin Pateman-Lewis / shutterstock
Our results are now published in Nature. Overall, we found that environmental features were the most important, particularly human impacts on the environment – how many other alien species groups were already present, for example – and how well the new environment matched what the species was used to from its native range.

The matching effect is not surprising – introduce a tropical parrot to the Arctic and it’s probably not going to do very well – but it is reassuring, as it gives us confidence in our analysis. This makes the anthropogenic effects more worrying though, in particular that alien birds are more likely to establish populations in areas that already have more aliens of other sorts. This is consistent with the “invasional meltdown” hypothesis that previous invasions help facilitate future alien arrivals.

The meltdown result does not simply reflect general environmental disturbance, as we also found that alien birds are more likely to establish themselves in less disturbed habitats – for example, areas where lots of habitat had been converted to cropland in the run up to the introduction.

Another sort of disturbance that matters is bad weather – a big storm in the period immediately following introduction can cause the alien population to disappear. There was already anecdotal evidence for this – for example, the initial extinction of the alien house crow population from Mauritius following a storm – but our analysis shows that this is a general effect.

We did find some evidence that lots of native bird species meant alien birds were less likely to establish themselves, but alien birds do slightly better in areas with at least some similar native species rather than none. This makes sense – for example, an alien bird that eats insects might be expected to do better in areas where native insectivores live, as long as there aren’t too many for the aliens to make a living. Overall, however, the types of native plants and animals had a relatively weak effect on alien bird establishment success.

While the environment explained most variation in alien bird establishment overall, we also found large effects of species traits and number of individuals introduced. Founding population size needs to be large enough (more than about 50 birds) to avoid the alien population failing simply by chance (the same reason we worry about very small populations of threatened native species). Assuming there are enough birds, then it helps if they breed fast but don’t die too young. It also helps if they are not too fussy about what they eat or where they live.

Taken together, our results show how features of the environment, the species, and the founding population size have all influenced the global history of alien bird establishment. They also suggest reasons to worry. The world is showing signs of a global invasion meltdown, while ever more alien species are being introduced to new locations and getting the chance to test their environmental matches. Increasingly, the future is looking alien.

Why don’t hummingbirds get fat or sick from drinking sugary nectar?
If you have a hummingbird feeder filled with sugar water, you might have the impression that all that hummingbirds need to live a healthy life is to sip sweet drinks all day long.

Believe it or not, these tiny birds need other types of fuel as well. While sugar makes up a large component of their diet, they also need proteins, fats, vitamins and minerals to be healthy. Their largest source of protein is from eating insects. If you watch hummingbirds near your feeders, you might get to see them do some erratic, zigzag flying – this is how they catch small insects flying through the air.

I’ve been studying hummingbirds for 10 years, and as part of my research, I place tiny aluminum bands on thousands of hummingbird legs to help me learn where they migrate and allow me to monitor how healthy their populations are each year.

What else do hummingbirds eat?
Hummingbirds will also pluck insects directly off of flowers, shrubs and trees. Some of their favorite bugs includes small flies and gnats, ants, tiny insect eggs, larva and even small spiders.

Some people report seeing hummingbirds eating dirt, sand and campfire ashes too. Ornithologists suspect this is to gain certain vitamins and minerals. They are also known to eat pollen and even tree sap. So a hummingbird diet is actually quite complex and varied, and they can’t eat sugar alone to survive.

When humans eat too much sugar consistently, their blood sugar levels rise and they are at risk of getting diabetes. Hummingbirds’ anatomy and digestion are very different from humans. While nectar accounts for about 90% of their diet, hummingbirds don’t get diabetes since their bodies are designed specifically for digesting sucrose. With a heartbeat that can reach 1,260 beats per minute, hummingbirds need the sugar rush.

A hummingbird slurping nectar from Salvia officinalis flowers. Kit Leong
How to attract and feed hummingbirds
Diluted white sugar most closely resembles the sucrose nectar of flowers the birds feed on. You can easily fill your feeders with sugar water. Mix four parts water to one part white sugar and then boil, cool and fill the feeder. Remember to clean and refill your feeder every few days, especially in hot weather. A dirty or moldy feeder can make hummingbirds sick.

Don’t ever use brown sugar, honey, or any other type of sweetener, which can harm a hummingbird. For example, brown sugar has too much iron in it. Try not to make it too much sweeter than a 4:1 ratio because it is harder for them to digest. There is such a thing as too sweet, even for a hummingbird.

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Did you know that hummingbirds probably don’t want red dye added to their sugar water? Red dye serves no healthy purpose for their body (or yours). Most red dyes are petroleum-based, and it makes their p**p red, which is unnatural.

The red color on your feeder is enough for a hummingbird to find it. Or consider planting some red or purple flowers in your garden, like Salvias or Monardas – hummingbirds love them and they’re great sources of insects too.

So don’t be shocked if a hummingbird zips past you feeder and ignores a fresh batch of sugar water. It might be focused on getting its protein fix and catching a flying gnat right out of the air.