Angela Camargo: exploring animal-plant interactions in Latin America

Prof. Angela Andrea Camargo Sanabria is currently working for the Department of Natural Resources of the Faculty of Zootechny and Ecology at the Autonomous University of Chihuahua, which is part of the Science and Technology National Council (Conacyt) chair programme. Her studies focus on community ecology, plant-mammal interactions and mammal behavioural ecology.

On the occasion of the MAB programme's 50th anniversary, she discusses her research on animal-plant interaction in the field, the impact of the pandemic, and finding joy in science.

Let’s start with you arriving in Mexico for your studies. That’s where you would later begin to work in research.

Yes, I did my master's research on white-tailed deer populations in the Mixteca Poblana, which is a tropical dry forest area. During my PhD, I worked in Chiapas, in the Montes Azules Biosphere Reserve. Currently, as a researcher, I am working in arid zones in northern Mexico.  We are looking to work on systems called ‘sky islands’, which are basically isolated mountains in the middle of the desert each with different types of vegetation. They are very interesting systems from an ecological point of view. They are found in an area between Chihuahua and Coahuila and between Chihuahua and Sonora. We are currently working to describe and quantify mammal richness patterns along altitudinal gradients in these arid zones, so the sky islands are perfect systems for these studies.

At the time, why did you decide to apply for the UNESCO MAB Young Scientist Awards?

During 2012, I had no funding to go out to the field, my research project had a seed fund, but there wasn't much else. I was already a year and a half into my PhD at that point.

So, I started looking for sources of funding and sent my proposal for small grants that would not involve partnering with an association or civil organization, so that as a student I could manage the funds freely. That is how I found out about the MAB Young Scientist Awards.

If I remember correctly, the application process for the MAB Young Scientist Awards required an application first from the Mexican government and then from the Mexican Commission for UNESCO. I wrote to Dr Sergio Guevara, who had been my professor during my master's degree at the Institute of Ecology in Xalapa, in Veracruz, in Mexico, crossing my fingers that he would remember me, and he replied: "send your proposal" and so I only had to adjust it to the requirements of the call.

Out of the 10 or so proposals I sent to various sources, two were successful: one with the MAB Programme and one with the Kew Botanic Gardens in England, which helped me with laboratory analysis.

What was your experience of using the 5,000 USD grant funding from the MAB Young Scientist Awards?

My project involved setting up camera traps to monitor animals in the Montes Azules Biosphere Reserve, in Chiapas in Mexico. By the time I received the UNESCO award, I already had 15 or 20 camera traps, which was sufficient for my project. Fortunately, I had received other resources that allowed me to pay for the equipment. If I had had to buy them, I would not have been able to afford them, because at that time a relatively good brand of camera cost about 200 USD.

Most of the resources I received from UNESCO were used for field mobilisation. The Montes Azules Biosphere Reserve is located in a remote area that borders the Usumacinta River, which also borders Guatemala. To get there, you have to travel by interstate, urban and private transport.

In the biosphere reserve there is a biological station that is managed by a civil association. However, I decided not to stay at the station, preferring instead to stay in the ejidos, the rural communities where the people who were going to help me with the fieldwork lived, and this helped to reduce the costs of my stay. These people rented us a small house where many students lived, and the daily life was much more pleasant. But this meant that every day we had to travel by boat from the ejido to the biosphere reserve, which was separated by the river. So, a large part of the budget was used for the fuel for the boats and the fair wages of the two or three people who helped us every day with intensive work.

The MAB Young Scientist Award also allowed me to take two undergraduate students to the field to carry out research for their thesis as part of my PhD project.

One of the undergraduate students used the data I produced in my PhD thesis - with the camera traps - to analyse animal behavioural issues, which earned him an honourable mention for his undergraduate thesis and won third prize at the National Ecology Congress. The registration fee was also paid with funds from the UNESCO Young Scientist Award, so we can say that we maximized the funds.

One thing worth noting is that UNESCO does not ask for a technical or financial report at the end of the research, it trusts that the resources are put to good use. In Mexico, any money received, whether from the university or the government, must be checked. I think it's good to check the use of resources, but it gets very complicated when you are in field situations.

For example, in Comitán - one of the largest towns closest to the biosphere reserve that is still located four hours away - there are supermarkets of well-known chains that can give you an invoice, but you also need to pay more. The same purchases can be made in the community, contributing to a small economic benefit, because you buy cheese from the lady who produces the cheese, meat when an animal is slaughtered from their plots of land, etc. The resources yield more in the ejido than if you had to prove everything in the city or the municipal capital.

So not having to check the use of the resources actually helps a lot and allowed us, in the long run, to make very good use of them. Above all, it allows to pay fairly the people who collaborate with you, that is very welcome and appreciated.

Let’s dig into the research. What do large mammals teach us about biodiversity? And more specifically in the case of herbivores, what do they teach us about the relationship between flora and fauna?

Mammals are a very well-studied group because they are very charismatic. It is probably easier to get resources to study these species than to study a beetle. Also, they simply have a very important ecological role. Some mammals are recognised as ‘umbrella species’, which means the protection measures we put in place on behalf of these species will have a positive impact on other groups of less charismatic organisms. In addition, mammals are a functionally very diverse group. They include diurnal and nocturnal animals, some that inhabit the ground, burrows, trees and others that fly. With regard to food, some feed on meat, grass, fruit, seeds or nectar. Simply put, they are functionally very diverse, and this allows us to approach the functioning of communities and ecosystems in a very comprehensive way.

The main topic of my research was the study of plant-mammal interactions, so I focused on the role of herbivorous mammals. With my PhD thesis I wanted to find out what would happen to the diversity and species composition of the regenerative plant community, i.e. seeds, seedlings, juveniles of the rainforest, if they lost their interaction with herbivorous mammals as a result of their disappearance.

Tropical forests are characterised by a high diversity and many theories have been put forward about their origin to explain the mechanisms that allow them keep maintaining themselves. One of these theories is precisely the regulatory role of animal populations.

We wanted to see what would happen if mammals were not present, so the biosphere reserve model was ideal for carrying out this research. Through a series of experimental exclusions of mammals, we defined areas where we knew mammals were present and areas where they were not, in order to compare the effects.

What we did was to prevent mammal access to certain areas by fencing them off, and there we monitored for 60 months the plant communities in terms of their survival, recruitment, density, species richness and diversity. The challenge was to quantify the presence of mammals and their importance for those sites. That was the work we did with camera traps.

With my PhD research, I was able to show what happens when we exclude mammals. When we eliminate them experimentally, there is an impact on plant communities. If there is no one to eat them, some plant species will compete aggressively and will manage to dominate the community. While other species that grow more slowly or defend themselves much less, for example,  become rare in those communities. As a result, without the mammals, we end up with very inequitable plant communities, i.e. very unbalanced in their abundance and therefore less diverse.

I was able to demonstrate this effect at the regenerative community level, as I said before, the level with the seeds, seedlings and juveniles. But several other studies have shown that the impact we see at that level also lasts in the adult tree communities. We probably don't see it at the moment, because these trees live much longer than we do, but we do foresee impacts in the very long term.

And this change in the composition of forest species does not end there, but will have an impact, for example, on the capacity of these forests to store carbon, because some species capture more carbon than others. If we intervene to change that composition, we end up having a negative impact that would harm us eventually because this is an ecosystem service, that is, a service that humans obtain from biodiversity and ecosystems.

Tell us more about how you used these camera traps.

The camera traps were used to monitor the presence of these animals at different points and to make the connection with the plant species.

I came up with the idea of placing camera traps not only to verify the presence of mammals but also to quantify the importance of different mammal species in the interaction with plants.

We placed the camera traps in trees that produce fruit and that we knew were consumed by mammals to see who came by, how long they stayed and what they did - if they spat out the seeds, if they swallowed them, etc. With this information we were able to infer which species were dispersers, for example, and so that gave us a more interesting and complete story about the interaction and the benefits or impacts on plants.

In general, with the three chapters of my thesis, we were able to describe and quantify more completely the interaction that mammals have with plants, whether through the consumption of leaves, stems or fruit, but also through the trampling that they do as they move around and the possible dispersal of seeds to new sites.

What did you learn about the behaviour of large mammals from monitoring?

With the data from the camera traps, you know exactly on what date and at what time the animals are present, it is the metadata from these files from which you perform a lot of analysis. For example, you can estimate the level of segregation between animal species, meaning how they do not mix, which allows you to understand how so many species can coexist in the same environment. When you look at the times and dates when animals arrive, and if you look at all the trees as a whole, you have data on spatial and temporal activity. That gives you a better idea of how the forest works.

We demonstrated that at a local scale, animals can coexist in the same space without competing for food. When we analysed the times at which each species came to the site, we found that their activities did not overlap: it was as if each species waited for its turn to go and eat.

For example, the activity peaks of the tapir, a highly nocturnal animal, were registered between 20:00 and 22:00 hours, and then in the early morning, and in the intervals, you would see other small animals such as the paca (Cuniculus paca). It is as if they knew who was going to be there at what time and decided not to show up. They ate other fruit and achieved a "friendly" coexistence.

As a result of these observations and analyses, we published two articles: one describes the interactions of frugivorous mammals with the fruit of two tree species and the other quantifies their daily activity patterns.

From your perspective as a Colombian scientist based in Mexico, what are the common emerging perspectives for the Latin American scientific community?

If you had asked me this question four years ago, I would have said something else. I think that at the moment, at least given the situation that the academic scientific field in Mexico is going through, my perspective is a bit discouraging. However, we continue to work, Mexico continues to be a very attractive country for many Colombians and Latin Americans in general because there is a vibrant community of scientists trying to generate high-level science and there is academic support to study.

I hope that the pandemic invites us to reflect on the importance of science. The COVID-19 vaccine did not come about overnight, there is a great deal of research behind its development. And it is that basic information that now allows us to have a tool - in this case vaccines - to be safe and to continue our activities.

What is the current place of indigenous peoples and women in and for the Latin American scientific community?

I have not worked with indigenous communities. But from what I see in publications and also on social media, there are more and more initiatives to give visibility to indigenous scientists. What I have seen are many initiatives by colleagues in Colombia, Ecuador and Mexico that seek to promote this diversity; it is a lesson that nature teaches us. Diversity is very good: the more different we are, the better.

From your point of view, what should be the focus of the Ibero-American MAB Network (IberoMAB), comprised of biosphere reserves in 24 countries in Latin America, the Caribbean, Spain and Portugal?

I believe that bringing science closer to the public is fundamental. We need to work on "scientific literacy": explaining how science works. It is not about everyone becoming a scientist, but about creating curiosity and getting every citizen to question everything and all the time. For example, from what a politician says to what they are going to do when they get home.  The network should work more closely with universities to strengthen the link between science and citizens at local and regional level.

More recently though, I feel that the two years that we have had to lock ourselves indoors because of the sanitary crisis have highlighted the fragility of our emotional health. And in this context, the value of interacting with each other has become more than evident, as evident as the need we have to connect with nature. The value of green and protected areas for maintaining our emotional and mental health is extraordinary.

However, we are lacking more studies in this field in Latin America, as for the moment research on this topic has been carried out mostly in the United States and Europe . We need to produce more studies to quantify the value of protected natural areas from a more holistic perspective, not only biological, and even perhaps to give them a monetary value. Also, considering that it is already a reality that most of the world's inhabitants live in cities, this network and the programme in general should redirect efforts to study biodiversity in cities and also its role in our well-being.

The information about the way nature or natural areas benefit our health is vital to guide public policies in terms of planning our cities.

Do you think that, 50 years on, the biosphere reserve model is still relevant?

I think so. This model - especially in Latin American countries - is very relevant because they are countries with high population density, which continues to grow, and in which people make use of natural resources for their livelihoods. So, you cannot take people out of protected areas, but at the same time we need more protected areas to conserve biodiversity.

We are not going to be able to protect the biodiversity in highly anthropised areas, but we need biosphere reserves because they try to combine, in the friendliest possible way, the presence of people with nature, considering that in many cases people were already living in these territories before the protected area was designated.

Self-managed projects should be promoted that allow people to stay in their communities and take ownership of the initiatives, instead of imposing a project, for example, that a researcher brings in from the city. It is also important to continue to work with politicians, to ensure that these successful initiatives become long-term policies or regulations that cannot be stopped when there is a change of government.