This is just a short little post about some science that I read in the papers this week. These two stories were interesting for very different reasons.

The first one is something that you've probably seen on Facebook, but just in case you haven't I thought I'd share it. Danish researchers have predicted the distribution of mammals if humans have never existed: http://i100.independent.co.uk/article/what-the-world-would-look-like-if-humans-had-never-existed--WJmrb1dBlHg

This comes hot on the heals of other work that shows we are the most efficient hunter on the planet: http://www.independent.co.uk/news/science/forget-jaws-it-is-humans-who-are-the-worlds-top-predator-say-scientists-10464301.html

But work like this, while interesting, should not be taken as gospel. There are many assumptions that go into a prediction like this. And a big one that many people will probably point out is the assumption that we were the cause of the Pleistocene mega fauna extinction. To my understanding we most likely were, but there is still debate.

The second story is about ants who self medicate: http://www.independent.co.uk/news/science/ants-are-able-to-selfmedicate-by-changing-diet-when-they-are-unwell-in-first-for-insectkind-10467040.html

This is just cool research. It's by Finnish researchers and show that ants infected with a fungus will eat hydrogen peroxide, something that healthy ants won't do. Doing so reduces their risk of dying by 15%, but comes with a 20% risk of death. However, this fungal infection is deadly and can wreck colonies. The ants also dosed themselves. This adds to work showing that animals eat plants when sick or rub specific vegetation on them to reduce parasite load. It's also interesting because it shows a species with very limited cognitive capacity can appear to have such self awareness.

Sorry if the links aren't as easy to use. I'm writing this on my phone!

The story of the dreaded neonicotinoids and there proposed deadly effect on Europes bees has been reported widely in the press over the last year or so. The story has gotten ugly as there have been claims and counter claims of dodgy science on both sides of the debate. But pesticides in general may be having an effect far wider than just on bees.

I'll state first up that I am not anti-pesticides. Without them modern agriculture couldn't exist, we'd have much higher food prices and no doubt people's diets would be worse for their absence. But they will have an environmental impact that is far less easy to detect than any 'endocrine disrupting' effect that groups like the Pesticide Action Network rave and shout about.  What is needed is an informed discussion about the risks that these chemicals have, not only to bees and humans but to wildlife further afield. Using long-term demographics and detailed studies of birds and other animals we can hope to determine these impacts. Unfortunately, many of the staunch anti-pesticide campaigners are also very anti GM: a technology that has the potential to actually reduce our impact on the environment and increase sustainability. 

Pesticides kill insects, that is what they are designed to do. Almost all non-ratpor or seabird species (I can't think of an easier way of writing this!), whether they as adults each insects or seeds, feed their chicks insects. As a food source, as many an alternative website will state, insects are very high in protein - the ideal thing for a growing chick! With the majority of the UK being either urban or under agriculture that leaves environments that are either a) probably fairly low in insects or b) get sprayed with pesticides to reduce the number of insects.  Many species of native British birds are on the decline, house sparrows declined by 71% between 1977 and 2008, common cuckoo number are hugely down, there is obviously a problem but is it a singular one or is each species decline due to their own specific factors? However unique the behaviour and ecology of each declining species, It seems that more and more studies and ornithologists are at least in part blaming pesticides for the reduction in bird numbers. If birds are unable to feed their offspring then recruiting individuals into the population is reduced, and as birds age or die from disease or predation then the population will decline. And if the adults themselves rely on insects for their own food then surviving or getting up to reproductive weight becomes even harder.


It is very difficult to show causation in situations like this, as all that most researchers have is historical records of bird populations and pesticide use. To complicate things further pesticides are not the only thing that can lead to a reduction in insect abundance. Changing land use practices, such as cutting down hedgerows or increasing stocking density are also likely to have impacts on insect abundance. Controlled trials where specific areas are allowed to use pesticides and others are not would be great, but they are expensive and, for an issue like this, long-term. And with our governments current track record for environmental experiments (i.e. the badger cull) few would likely trust the results.


However, the decline of British birds cannot be put solely at the feet of pesticides. Many of our birds have long and complex migrations which we are only now starting to understand. Changes in land use, hunting or a number of other things may be impacting them at various stages along their migrations. For example, in Malta every year thousands of migrating birds are shot - which I find repellent. The decline in insect numbers in the UK may also be due to climate change, insect populations are likely to decline as flowering times and insect emergence times become increasingly out of step.  

So conclusions? I don't have any. I'm just hoping that this issue gets wider attention and enters the debate into both the use of pesticides and the potential benefits of GM.

So this week saw the start of the annual grouse shooting season, the "glorious twelfth" or as many news papers reported it: the "inglorious twelfth." This controversial sport has received more media attention than ever this year because of the publication of a new study.

But the conflict between environmentalist and grouse shooting is a long standing one. There are the ethical and moral issues that are entangled with any hunting but they are also caught up in class and land ownership struggles in Scotland. This form of hunting is associated with strong association with falls in the numbers of birds of prey, most notably in the UK the hen harrier. Claims and counter claims about the meddling of conservation groups further cloud the issue for members of the public.But game keepers are regularly charged with poisoning these beautiful birds and they are found shot, poisoned and beaten to death. But grouse shooting is an economic boon for the Upland areas of Scotland, bringing in a reported £2bn a year, supporting many jobs and local businesses. 

This is when conservation is at its hardest, when the wishes of the "green faction" are so starkly opposed to economics. If protecting hen harriers was going to create jobs and bring in money then the argument would be easy and the species would be saved. In situations like this maybe the best course, and this is probably very controversial, is a middle course (very Buddhist of me!). Finding some way for jobs to be maintained because of the shoot, while also protecting the raptor species. Some form of RSPB stamp of approval for raptor friendly estates perhaps? EU grants to those who work with conservationists and change their ways? I'm not invested or knowledgeable about this conflict by any means and so for all I know these have been tried in the past. However, money is a huge lever for humans and so when economics is so against a conservation issue it really needs to be addressed.

But what of this new study that I mentioned at the top? Well it turns out, along with being bad for birds of prey, grouse shooting is contributing to climate change. This may be the lever that conservationists can use, for two reasons: firstly, climate change is a hot (pardon the pun) emotive issue that multiple people and campaigns can get behind, and secondly, some form of emissions tax is possible in the same way that it is imposed on big businesses. By burning the heathland the estates create better habitat for the grouse, but they are also burning large swathes of peatland. Peat is a carbon sink, so by burning this habitat they're causing a double whamy: releasing CO2 from the burnt plant material and stopping the peat from storing CO2. So maybe this can be this revelation is what can make the change, but with a Tory government in power and having already attempted to loosen the ban on fox hunting, I doubt they'll risk further reducing their support in Scotland by taking on the big estate owners. Oh, how fun it is to be politically cynical! 

The paper mentioned above:

Douglas et al. (2015) Vegetation burning for game management in the UK uplands is increasing and overlaps spatially with soil carbon and protected areas. Biological Conservation, 191:243-250
Burning for habitat management is globally widespread. Burning over carbon-rich soils is a global environmental concern due to the potential contribution to climate change. In the UK, upland heath and blanket bog, so-called 'moorland', often overlies carbon-rich soils, and has internationally important conservation value, but is burned as management for gamebird shooting and to a lesser extent for livestock grazing. There is little detailed information on the spatial extent or temporal trends in burning across the UK. This hinders formulation of policies for sustainable management, given that the practice is potentially detrimental for soil carbon storage, water quality and habitat condition. Using remotely sensed data, we mapped burning for gamebird management across c45 000 km2 of the UK. Burning occurred across 8551 1-km squares, a third of the burned squares in Scotland and England were on peat ≥ 0.5 m in depth, and the proportion of moorland burned within squares peaked at peat depths of 1–2 m. Burning was detected within 55% of Special Areas of Conservation and 63% of Special Protection Areas that were assessed, and the proportion of moorland burned was significantly higher inside sites than on comparable squares outside protected areas. The annual numbers of burns increased from 2001 to 2011 irrespective of peat depth. The spatial overlap of burning with peat and protected areas and the increasing number of burns require urgent attention, for the development of policies for sustainable management and reversal of damage to ecosystem services in the UK uplands.
LINK

 

One of my friends, Jamie Samson, has just had a paper published and it's pretty cool. He work on Cape ground squirrels, an animal that sends most of its day just calmly searching for food around their large burrows and then occasionally go crazy and have fights that could be scenes from the Matrix. These guys stash food away to save it for later in a behaviour known as caching. What Jamie found was that they pay attention to who is looking when they do it, to avoid being seen. This makes sense, as they can avoid their caches being stolen, but Jamie also found that the dominance rank impacted caching behaviour. Dominant individuals were less concerned with being observed than subordinates. It's cool work that builds on other investigations of caching species like scrub jays.

Samson & Manser (2015) Caching in the presence of competitors: Are Cape ground squirrels (Xerus inauris) sensitive to audience attentiveness? Animal Cognition 
When social animals cache food close to their burrow, the potential for an audience member to observe the event is significantly increased. As a consequence, in order to reduce theft it may be advantageous for animals to be sensitive to certain audience cues, such as whether they are attentive or not to the cache event. In this study, observations were made on three groups of Cape ground squirrels (Xerus inauris) in their natural habitat when they cached provisioned food items. When individuals cached within 10 m of conspecifics, we recorded the attentiveness (i.e. whether any audience members were orientated towards the cacher, had direct line of site and were not engaged in other activities) and identity of audience members. Overall, there was a preference to cache when audience members were inattentive rather than attentive. Additionally, we found rank effects related to cache avoidance whereby high-ranked individuals showed less avoidance to cache when audience members were attentive compared to medium- and low-ranked individuals. We suggest this audience sensitivity may have evolved in response to the difference in competitive ability amongst the ranks in how successful individuals are at winning foraging competitions. This study demonstrates that Cape ground squirrels have the ability to not only monitor the presence or absence of conspecifics but also discriminate individuals on the basis of their attentive state.
LINK

This week I was interested to see what sounded like some really cool new science reported in the Daily Mail, with the print headline of “Seagull gangs ‘are pricking on women.’” From briefly skimming the article it seemed that the much maligned blight of British seafronts had developed a novel foraging tactic, with “targets more likely to drop food when pecked.” The eponymous words of Jurassic Park rang through my head “clever girl.” But on a closer read it seems that this new revelation, reported as if it were fact, is just the opinion of two lifeguards, Ash and Becca. So is Mail is just reporting non-fact as fact once more?

 

On the face of it yes, as there doesn't appear to have been any research into this and it’s just someone’s view. But seagulls are smart and other smart birds have the ability to remember the faces of humans for decades, so it seems perfectly sensible to suggest that seagulls could tell men and women apart. But what about using some crazy foraging behaviour?

 

It turns out that there is actually precedent for targeting a subset of a population to steal food from. Fork-tailed drongos, amazingly acrobatic birds that have a dual impact on other species: they can act as a sentinel system, allowing others to spend more time foraging, and alerting them when predators are near but they can also make false alarms and steal food. So, there is a both a cost and a benefit to having these duplicitous birds around. I’ve blogged about some of the cool interactions of drongos before. Drongos follow pied babblers, with smaller babbler groups paying more attention to their sentinel behaviour than larger ones. The interesting thing is that within pied babbler groups some individuals respond more to drongo alarm calls than others, with juvenile birds more likely to respond. Drongos will actually preferentially target these juvenile birds, making their stealing more efficient. This is really similar to what the Mail suggests is happening on British beaches.

 

However, it still needs to be researched. So if anyone wants to fund me to go to the beach to collect data and run experiments…..

 

The above research is published in Ridley & Child (2009) Behav Ecol Sociobiol 63:1119-1126

 

Other cool drongo papers:

 

Flower & Gribble (2012)

Flower et al. (2014)

Flower (2011)