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We are rainforest ecologists working to protect spider monkeys, Amazonian birds, and the rainforests they inhabit. Ask us anything!

Hi Reddit! We are Cristina and Jenna, tropical rainforest ecologists at Imperial College London working in Amazonian Brazil and Costa Rica. Ask us Anything! 

We'll be answering your questions until 6 PM UK time / 1 PM Eastern time.

Proof -

The planet is going through an unprecedented rate of species loss. Last year a United Nations report concluded as many as 1 million species are at risk of going extinct in the coming decades at a rate 1000 times higher because of human action.

The tropics are at the frontline of this crisis. They are home to 75 percent of all species and 40 percent of the human population, many of whom live in poverty and rely on working the land to make a living. We urgently need to find ways to combine biodiversity conservation with human welfare.

As tropical ecologists, we work with authorities such as the Brazilian government to advise on policy-change that seeks to avoid biodiversity extinction. To do this we need to understand what exactly is driving species to go extinct and what the impact their disappearance has on the environments they leave behind. With this information, we can identify critical thresholds for forest loss to further inform policy, and we plan ‘wildlife corridors’ to help species navigate around humans and our expanding tropical agriculture such as palm oil and teak plantations.

In Brazil, Cristina’s work led to the Brazilian government’s adoption of a 30 percent forest cover threshold across the country’s Atlantic Forest region. While in Costa Rica, Jenna has been part of a team setting up over 400 audio devices to record the sounds of the rainforest. We then used machine learning to pick out and track the calls of the forest’s endangered spider monkeys as well as getting a wider picture of local biodiversity loss.

During this AMA we’re happy to talk about the drivers of deforestation and how the resulting biodiversity loss plays out on the ground. We can discuss the limitations of reforestation solutions, and why you can’t ‘make up' for cutting down rainforest by planting trees elsewhere. Instead, we can discuss a more sustainable way forward which both preserves species and benefits local economies.

For more information

April 27th 2021
interview date

Is Bolsonaro public enemy #1?


Cristina here - well, what’s the best way of putting this? The deforestation levels were going down steadily due to lots of positive changes to governance and law-enforcing up until 2015. The month when Bolsonaro won the election the deforestation started going up and continues to go up. He’s always been clear in his goals of deconstructing the Ministry of Environment (which he has done successfully). He also cut all funding to research and education. So, I would say yes, but I suppose some people may disagree with me.


How do you work with local rainforest communities? How do you balance ecology preservation with their need to make a living?


Cristina here - I don’t particularly work with local communities as much but have many colleagues who do. The interesting thing about local communities is that their impact is often localised and much, much, smaller than big farms. Indigenous land in Brazil are among the best preserved areas in the country. The main issue really is illegal logging and non-environmentally friendly farms (or companies) that open huge swaths of land for planting monocultures. If we preserve the forest, we will also improve the livelihoods of local communities.


You've mentioned in a previous answer that the major problems aren't solved by individual action, but by larger governmental action. What can we, as individuals, do to help? Are there any particular politicians on your radar that "get it" who we should support? Are there particular companies we should avoid?


Cristina here - This is a very difficult question. I think one of the major things we can do individually is to vote for a party that has clear goals in advancing the environmental agenda. I personally try to buy products from companies that are also environmentally and socially friendly, and avoid (as much as possible) companies that I know are damaging the environment. But individually, how much can I change? A tiny drop in the ocean. Compare that with a policy of deforestation Zero, or discontinuing the sale of petrol-run cars. This has a much stronger impact on the environment. Food for thought - the lockdown last year was responsible for reducing carbon emissions to the level that are required to reach goals of 1.5C increase in temperature. It’s this level of behavioural change that is needed at the moment.


What do you think is the most effective method of reducing deforestation? Do you think that our growing population is contributing to our problem with deforestation?


Cristina here, thanks for your question! Growing population is a problem but the major problem is resource use. A recent paper showed that early humans have historically inhabited nearly all regions of the world but have not led to the destruction of habitats. It’s the way we overexploit our resources that makes it unsustainable. There are many ways that we can reduce deforestation - reducing meat consumption is one of them, as large areas in the Amazon are cleared for growing soy for animal feed. Strengthening environmental and enforcement policy is another way. Politics count a lot too. By 2014, deforestation in the Amazon had reduced to nearly 80% compared to year 2000s levels, but then recent changes to Brazil’s government have reverted this trend and deforestation levels are now increasing.


is there still hope for the rainforest?


Hi, Cristina here. There is. But we need to get our act together quickly enough. I personally don’t think this is something that individual actions can make much of a difference. First, governments need to understand that old-growth forests are irreplaceable, so news of increasing levels of deforestation cannot be dealt with more funding for tree planting. Second, strengthening environmental policies and enforcement can help a lot. For instance, according to Brazils’ forest code, landholders in the Amazon need to protect 80% of their land to native vegetation. If this law is enforced and extended to other areas of the world, we would be in a much better place now!


Sloths are my favorite animal and I just want to know, how in danger are my sloths? I know they depend a lot on staying in trees so I can’t imagine deforestation is doing them any favors.


Cristina here - sloths are incredibly cool. Sloths can handle some level of habitat disturbance, as in they are not dependent on old-growth forests, but overall I’m sure their populations are going down. Side note - when I was doing my masters in the Amazon, a colleague was a foster “mum” for two baby sloths that had been found (can’t remember what happened to their mum). This colleague used to carry them around in a basket attached to a plush toy and then she would give them a bottle every couple of hours. It was the cutest thing! (I should add that this woman worked for a reputable organisation involved in conservation there and we do not recommend having sloths as pets - not only are they better left in the wild, they are covered in parasites!)


Why do you think it's so hard for people to discuss the issue of human overpopulation? David Attenborough has brought this up many times in his talks.

Essentially, every additional human won't simply live inside their parents' land-footprint forever; they will venture out into the world, demanding new schools, new hospitals, new products, and new places to live. Where will this land and these resources come from? How long can the planet sustain this trend? How long can the planet even sustain the current number of humans alive right now?


Hi, Cristina here. Thanks for this question. According to the Millenium Ecosystem Assessment report from 2005, overpopulation is one of the indirect drivers of habitat change, other indirect drivers include: Economic factors (globalisation, trade, market), sociopolitical (e.g. governance, legal framework), science and technology, and cultural and religious practices. What this means is, overpopulation is a problem particularly if everyone is going to have the lifestyle typical of rich western countries, where you “need” a new iPad every year, drive a big SUV just to go around in the city, go abroad several times per year, and generally waste resources. Would environmental change also be happening if we had 8 billion people all with the lifestyle of rural people in developing countries? Sure. But we certainly wouldn’t be in the mess we are right now. Just blaming overpopulation often risks having a racist overtone because developing countries have high birth rates and developed countries have stable or declining birth rates. But the people who are actually driving environmental change are those in the developed countries. There’s no doubt about that.


What is the best thing any single person can do to help save the rainforest?


Jenna here - I think the best thing we can do is to look at our own consumption. A lot of what we consume comes from forests or is at the expense of forests. For example, palm oil in many food and cosmetic products, furniture from unsustainable timber products from the tropics. The land taken up for livestock and their feed is massive and is one of the main things driving deforestation, so I think reducing meat consumption is also important and eating meat and other food sourced locally.


Have you been surprised at the image most people have of Costa Rica vs the reality? The popular parks are in good shape, but there is still illegal hunting and logging going on in many protected areas, farmers use harsh chemicals with no regard for the health of themselves or local waterways, and the vast majority of Ticos see the jungle only as a place to make money via ecotourism like it doesn't have inherent benefits or interest on its own. It's still pretty good compared to many other Central and South American countries, but there's still a ton of work to be done. Where I live (Cordillera Tilarán) everyone knows who the local poachers are, they show up on my game cameras, but the MINAE staff is so overstretched that the chance of them actually catching a poacher in the act is near-zero, so the poachers go on as they please.


Hi, Jenna here - Costa Rica does indeed have a good image and you are right, there is a lot of illegal hunting and logging going on and pollution of the land and waterways. But I do think the positive image is overall well-deserved. I have come across local people who want to exploit nature and do not care, as there are in every country, but I have also met many locals who care deeply about nature, regardless of the income it brings them. I have even met very poor people who set some of their land aside for nature instead of farming it for income. As a nation, I think they care more about conservation than many I think.

The government is not doing things perfectly and there are many areas for improvement, especially in areas such as illegal hunting and logging, but they are more interested in making changes, more than other governments. The issues you mention regarding poachers and minae I think comes down to lack of funding, political issues and the difficulty in prosecuting someone even if caught. I have also seen this in the area that I work in and I hope this will change in the future.


Hello, I live in the tropics here. There are many deadly diseases in the tropics, such as dengue, yellow fever and malaria just to name a few. Do you think that we should eliminate insects(e.g. mosquitos) that proliferate such dangerous diseases in the tropics, or are their ecological significance outweighs the harm they brought to our health?


Cristina here - I know what you mean. I caught dengue and had the haemorrhagic type. I really felt like a bus had driven over me. Insects are very important because they form the food base for many other animals and they have an important role in the forested ecosystem. For instance, usually it’s just the females that feed on blood, and males have a completely different role. Just this week a vaccine for malaria was announced, which is amazing news, and yellow fever also has a very good vaccine. Realistically, I think it’ll be a lot easier to eradicate the disease or create vaccines for it, than to stop the vector that transmits the disease.


I haven’t heard much about Brazil’s Atlantic rainforest, are there any key differences that Make it distinct from the Amazon?


Cristina here - The Atlantic Forest is THE most beautiful forest in the world! It once was the second largest tropical forest in South America but it has now been reduced to less than 16% of its original extent. About 130 million Brazilians live in this region, which is also the home for São Paulo and Rio de Janeiro. But if you have ever seen a photo of Rio and the forests near the city - well, that’s Atlantic Forest. It is incredibly species-rich, it has one of the highest number of plant species in the world, and the forest structure is amazing! Imagine a forest full of bromeliads and orchids, and nice sandy beaches, it’s just beautiful.


Hi. What did y’all study and how did you get into this line of work? I’m a conservation biology student and hope to do something similar in the coming years. Thanks!


Cristina here - I did biology at undergrad (Federal University of São Carlos), then moved to the Amazon to do my Masters in Tropical Ecology (National Institute for Amazon Research) and then did my PhD in Ecology (University of São Paulo). I then got a fellowship to work in the UK (Imperial College) and got a job here as staff. I know other people had different routes to becoming an academic, but IMO doing conservation biology is certainly a good start!


Have you heard the song or seen the music video for “Amazonia” by Gojira? It’s about the deforestation in the Amazon and they were raising funds to help protect the indigenous people.


Cristina here - I’m afraid not! Sorry! Looks like a good idea though.


What is your favorite bird and what is the status of it?


Cristina here - I don’t have a favourite species. But I absolutely love hummingbirds. They are the coolest animals. Their heart rate is about 500 beats per minute. They are super territorial and have very high needs for food. They are the Masseratis of the animal kingdom. But they also have a very important role in pollination and in predating mosquitoes. Some species are going down in abundance and some are threatened but overall this is not one of the most sensitive groups as they can easily cross open areas (e.g. are not that affected by deforestation) and they cannot be kept in captivity, so are not persecuted by animal trade.


thank you for your service in helping to protect endangered species!

What's your favorite animal species that you've worked with so far? I'd love to visit the Amazon Rainforest someday


From Jenna: I dont have a favourite species, but my favourite group of animals are primates. They are so similar to us and when you see them in the forests you can see their emotion and feel a connection with them. They are also so important for the ecosystems that they live in. I do have to mention insects as well, they are often overlooked but are all fascinating and play key roles in our ecosystems.


What is the most imminent danger to a spider-monkey?


From Jenna: This varies a little based on the country, but across their range it is forest loss. This species is a forest specialist and cannot survive without large areas of mature forests. Across their range the forests are being destroyed mainly for agriculture, forest products and urban areas. They are also at risk from hunting and the pet trade. In many areas people will eat the meat of the spider monkey and capture babies from their mothers to be sold as pets.


Is anything done with hunting-tourism to provide an alternative source of income that does not rely on destroying the rainforest for timber/farming?


Hi there, Jenna here. Ecotourism can provide a source of income for local communities to reduce their reliance on products from the rainforest or agriculture. For example, in Costa Rica many local people who used to mine for gold, which destroys forests and rivers, and many who used to hunt wild animals for meat or log forests for timber, are now engaged in ecotourism businesses, through being tour guides. If you are specifically talking about hunting as a form of tourism to reduce reliance on timber/farming then this activity is not common in rainforests and is more limited to other ecosystems. Does that answer your question?


What are the biggest impediments to your work on the ground? Is it covid, brazilian politics, local opposition?


Thanks for your question!

Jenna here - For me the biggest barrier is turning your work into conservation action. We can find interesting results and know what changes need to be implemented to improve wildlife populations and conservation, but finding both the funds and local and national cooperation to implement those results can be challenging. In Costa Rica the government is quite receptive to conservation, however this is not the same in all countries. Unless you have cooperation of local people, any conservation actions taken will likely fail. Having local support is therefore key, which can also be challenging.

Cristina here - Brazil is in a state of emergency at the moment. Most hospitals are over capacity, ICU’s don’t have medication for putting patients on ventilation anymore, the situation is really dire. We can’t go to Brazil and the team I have there cannot do field work at the moment, as this would put local people in danger. The Brazilian government has also cut funding for science and education so many students there can no longer fund their research or go to the field. But generally, Brazilians can be quite receptive to people working on environmental issues.


How are the freshwater mussels, newts and salamanders holding up? Folks don’t seem to care much here in the US.


From Jenna: These aren’t the ecosystems that we work on but as ecologists we are aware that freshwater ecosystems are among the most endangered in the world, and they are starting to receive more attention. For example in Costa Rica, they have just started a healthy rivers initiative and there are movements to reduce pesticide use and agricultural runoff, which are some of the key drivers of pollution and extinction in these ecosystems. I believe similar initiatives are going on in the UK. If you are interested in these systems you could try and find a local conservation group working in this area and offer your time to help them.


How much harder is everything with Bolsonaro's Goverment?


Cristina here - a lot harder. The consequences of the funding cuts to environmental protection, education, and science are going to be long-lasting.


I’m still at a university for Plant and Soil Science, mostly focusing on soil nutrients and it’s conservation. Is this an area that plays a big role in your research? I feel like we are learning more and more that soil health is vitally important. I live in a place where the main focus is agriculture but I am interested to know how mass deforestation, whether due to logging/oil farming or clear cutting, has an effect on the soil. What aspects of soil health do you study and how does this factor into the bigger picture?


Cristina here - Absolutely, this is a super important part of our research. I work with folks asking questions about how land-use change impacts nutrient cycling and soil microbes, as well as invertebrate taxa. New technology is allowing us to ask even more interesting questions. You’re in the right field!


Hi thank you for this! After reading this I realize there's a part of me that's really interested in species conservation and I was just wondering if I needed special education to get involved? And if not, how I could be more involved. Thank you again for your work!


Cristina here - That’s great to know! There are many ways of helping and the amount of education you’d need would depend on how you want or can help. Volunteering in a local charity group or chapter of a NGO for instance can allow you to help with protection of species on the ground while slowly building your knowledge. But if you are keen on working on this then there are lots of different ways that you could have impact. Government agencies or NGOs are usually the best ways to have direct impact. It may be that you may require some extra knowledge to get into these jobs, depending on your background. Alternatively, if you don’t have any time to spare then donating to a worthy cause can certainly help too!


How does someone break into the ecology field without a related science degree, is it possible?


Cristina here - many ecologists have a different type of training. Some start out as mathematicians, physicists, economists, etc. Because so much of what we do is data analyses it is difficult to break into the field without any knowledge of sciences, but I would also say that there’s a lot of people with a social sciences and humanities background also working in ecology. Because conservation is so multi-faceted, we need knowledge from all areas to really come up with real solutions.


Have you heard of the French metal band Gojira and their fundraising?

Gojira Bring Amazonian Crisis to the Forefront....


Yes! Thanks to a previous comment on this thread!


How often do you shower?


Cristina here - in the tropics at least 2 times a day! When doing fieldwork, if it’s in a very remote location a river swim every day at the end of the day.


Can you think of ways in which computer scientists can help the cause?


Jenna here - Speaking from my experience working in bioacoustics, computer scientists were essential in my work. Without someone who was an expert in machine learning, we would have never been able to work on the scale that we have done, which will ultimately benefit conservation. I believe computer scientists and biologists working together is the future of bioacoustics and I am sure in many other areas of conservation. With our combined skills we will be able to do much more!


What are your thoughts on the concept of hunting poachers/ people who purchase endangered species?

Like we could sell hunting licences for people who buy endangered species parts. Or even own stock in companies who contribute to burning the rain forest. We could cut down the population of those killing the lungs of the earth on a financial level. While giving people who have a need to kill an outlet to do so.

Would something like this be viable to save our planet? Big game hunters stocking CEO's who profit from destruction?


Jenna here - This is a tricky one. On the one hand if you make something legal, you can regulate the industry and have more control over it, but then you could also increase demand and it serves as a signal that this behaviour and these actions are acceptable for future generations. There are some that claim their poaching serves conservation through killing old animals, however if you look closely into these activities and claims, it is often not the case.


What are the organisms most at risk from forest reduction? You said hummingbirds are not as effected but what is?


Jenna here - There are some species that are considered forest specialists, these are animals that rely on forests for food, shelter and reproduction. They often live on or in trees, source all their food from forest vegetation, do not travel through areas that are not forested and are very affected by any human presence or activity. These are the animals most affected by forest loss. The spider monkey, as with most primates, is a forest specialist, as are many other mammals, such as sloths, jaguars, tapirs and many species from other taxa such as species of frog, insects and birds.


How much of an impact is primary-source (grazing land for farm animals) and secondary-source (clearing land to grow food to feed farmed animals) to deforestation and habitat loss in the Amazon, compared to other causes?


Jenna here - Both have a huge impact, are interlinked and are the number one cause of deforestation in the Amazon and probably in most rainforest ecosystems worldwide, along with other agricultural products such as bananas and pineapples.


Do you ever need to deal with local and indigenous superstitions as a difficulty for recovering endangered species, as with the aye-aye?

If so, how does one handle this delicate situation?


Cristina here - I personally never had to deal with this issue and neither has Jenna. I agree it’s thorny and I don’t really know what’s the best approach. Sorry!


Why don’t more people also talk about the rainforests in Malaysian and Sumatra (I love 🦧)?


Cristina here - there is a lot of work going on in South-East Asian forests. You may want to look up the Safe project (, they do super cool research in Sabah, Borneo.


Do you think that biodiversity conservation, reducing deforestation and so on is intrinsically valuable or instrumentally valuable?

You mention combining human welfare with biodiversity conservation, but what about the welfare of non-human animals such as those living in the Amazon? Is the welfare of animals living in the wild taken into account when decisions are made, and if not, should it?


Cristina here - I think biodiversity has intrinsic value but ecologists/conservationists often feel like the only way to convince others of the value of biodiversity is to bring up their instrumental value. We often forget that we are also part of nature and we cannot live without it. But because the impact of biodiversity losses on us aren’t usually immediate, it’s difficult to convince others of the importance of biodiversity. I don’t think the welfare of e.g., Amazon animals are usually taken into account per se. They are considered in the sense that if we’re protecting their habitat, then their welfare should also be protected. It’s hard to have a single species or even single group focus in the Amazon, where there are millions of species, each with their own individual needs.


Jenna here - I hadn’t heard of this before but I can imagine what it means just by seeing them in the wild. When spider monkeys are on the ground, which is very rare but does happen when food is scarce, they often run from tree to tree and when they run, they run with their arms in the air, it’s very funny to see. They have such long legs and arms. This may be where it comes from.


Did/do either of you ever work with Michael Crawley? If so, were/are there incredibly high expectations for statistical proficiency?


Cristina here - Yes! I do work with Mick Crawley. He’s retired now but still goes to work every day. Silwood Park (one of Imperial's campuses) has a very long reputation for statistically proficiency among staff. True that not everyone knows as much as him, but this is certainly our forte.


What are your thoughts on Hempcrete? What's the number one thing we (common folk) can do to help save the amazon?


Cristina here - I have no thoughts on Hemcrete! Had not heard until now. Sorry. The number one thing to save the Amazon is to get the Brazilian government to reverse their actions of defunding the Ministry of Environment, defunding the environmental enforcement agency, and defunding science. But most of the products coming out of the Amazon are for global export. So we common folk can stop eating meat or buying meat from animals that are fed on soy coming from the Amazon. It’s very hard to fully understand the supply chain and there are some companies that are really taking this seriously (here in the UK at least). We can also be more mindful of where the wood we buy comes from.



What's the biggest challenge in your opinion to protecting the animals ?


Cristina here - It depends on which animals you’re talking about. Humans, pigeons, mice and cockroaches hardly need any protection. That’s the issue really, some species are really affected by environmental change, while others are not or are even benefited. So, the best way is to focus on the ecosystem, protect the ecosystem (e.g. forests) and then the animals that live in it will also be protected.


What if there was a spider called 'monkey spiders' would you protect them?


Jenna here - Of course!