The first World Bird Migratory Day (WBMD) was launched in 2006. The event was a success, and has since been repeated annually all over the world: in 2011 alone, 205 events were registered in 64 countries.
This year, WBMD was on 12-13 May. We asked Mexican ornithologist Paula Lidia Enríquez Rocha, a member of the Organization for Women in Science for the Developing World (OWSD), to tell us more about this annual event.
Paula Enríquez Rocha studied biology at the National Autonomous University of Mexico, obtained her MSc in wildlife management from the National University of Costa Rica, and has a PhD in animal science from the University of British Columbia in Canada. She is professor and researcher in the Land Ecology and Systematics Department of El Colegio de la Frontera Sur, based in Chiapas, Mexico.
Professor Enríquez Rocha, do you think it's important to celebrate World Bird Migratory Day?
Bird migration is an extremely important and fascinating phenomenon that happens regularly, every year. But most of us are unaware of the incredible journeys that birds undertake: they pass by overhead in their hundreds, without most of us noticing. By choosing to highlight and celebrate bird migration in this way, we have an opportunity to tell people about birds, their habitats and their conservation. World Bird Migration Day is always celebrated in May, because it's the peak of the migratory season, when many species fly north to breed. Activities are organized around the world that invite the general public to participate, including birdwatching, classroom programmes, public presentations, bird counts and bird festivals.
Your research is on tropical birds in Mexico. What can you tell us about the migratory routes that pass over Mexico?
Three flyways pass over Mexico: the Lake Mississippi route, the Pacific Coast route and the Central route. That's why Mexico receives more migratory bird species (313, to be precise) than any other country in America. American migratory birds – we call them 'Neotropical migratory birds' – include vultures, hawks, egrets, ducks, shorebirds, hummingbirds, flycatchers and warblers. During the migration season – and particularly in the two major migratory periods, autumn and spring – some 5 to 8 billion birds fly over Mexico, covering thousands of kilometres. Several species stay here for 6 to 8 months; others only pass through and, after feeding and resting, continue on their journeys.
Are migratory birds more vulnerable than other birds?
They are vulnerable in different ways. Several resident birds depend strongly on their natural ecosystems, and those are disappearing. While migratory birds can use different habitats during migration, they do face quite a number of dangers while travelling: antennas, power lines, wind turbines, high-rise buildings, reflective surfaces (large windows, for example), and of course extreme climatic changes such as hurricanes, tropical storms and wildfires, to name just a few.
What can be done to help protect migratory birds, and birds in general?
Many of the conservation problems birds suffer are man-made. That's why I organize outreach bird programmes and workshops for children in schools, and talks and events for the general public. I am an active member of the local bird club. Birds are threatened on all sides. On one side, there are the natural factors that limit population growth, such as the presence of predators, and the availability of water, food and shelter. On the other side, the impact of human activity on bird habitats can drastically reduce bird populations, even to below a critical density. Pollution, hunting, and changes in land use can disturb nesting sites and seriously endanger entire species.
How important are birds to the ecosystem in general?
Each species plays an important and specific role in the ecosystem. Some Mexican birds are extremely important: hummingbirds, for example, feed on nectar and thus (like bees) help to pollinate, occupying an ecological niche that is more or less comparable to that of insects in other areas of the world; vultures feed on carrion and play a crucial role in removing flesh before it starts to rot and spread disease; birds of prey, including owls, hunt rodents and insects, helping to control populations which often present dangers to human health.
Your research specialization, in fact, is a bird of prey, the bearded screech owl. Where did your interest in birds of prey - and owls - come from?
When I was a biology student I noticed that the International Union for Conservation of Nature (IUCN) list of endangered birds was getting longer and longer every year, due to high deforestation rates in tropical and temperate rainforests. I also knew that birds of prey, and owls in particular, had not been studied very much in Mexico. So I decided to focus on owls. Owls, in fact, are difficult to study: first of all because they are nocturnal animals, but also because they are few and far between, having very low population densities, and occupying relatively extensive home ranges.
I decided to focus on the bearded screech owl, or Megascops barbarus, because its habitat covers a restricted region, stretching from Chiapas to the Guatemala highlands. These birds prefer the damp conditions of pine-oak and cloud forests growing at high altitudes in mountainous areas, and this is an ecosystem that is very much endangered by high deforestation rates. But we still know very little about the species.
Has your research had any impact on the conservation of birds in Mexico?
The bearded screech owl used to be considered a 'rare' species. My studies show that in some places this species is not as rare as we once thought. However, it is distributed throughout very specific forested areas that are under threat from human activities such as logging. The risk that these owls will lose their habitat is very high. Based on my studies, it has now been proposed that the IUCN conservation category of the species is changed from 'Near Threatened' to 'Vulnerable'.
One final question, Professor Rocha. We contacted you about World Bird Migration Day because you are a member of OWSD, the Organization for Women in Science for the Developing World, a partner organization of TWAS. Has it made any difference to you as a woman scientist to be part of this organization?
OWSD has been particularly important for me because it is one of the more significant international forums for women scientists from developing countries. OWSD recognizes women scientists working and living in developing countries like Mexico, and also recognizes how we have contributed to the advancement of world scientific knowledge. Women face difficulties that men don't face in forging careers as scientists. We often have to overcome cultural and social barriers. We are encouraged to be wives, daughters, or mothers, but very rarely to be scientists. OWSD gives us this very important official recognition of our professional role. I know that there are fellowships and prizes, too, that OWSD offers - and these too, can certainly make a big difference to women's scientific careers.