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Expert Q&A: Eugenie Regan

Irish ecologist, researcher, naturalist and author Eugenie Regan tells us about her work assessing invertebrate pollinators at the national, continental, and global level.

Dr. Eugenie Regan is an Irish ecologist, researcher, naturalist and author. She has authored over 40 scientific papers and books, including the definitive guide to the insects of Ireland and global guidelines for butterfly monitoring.

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You are an entomologist, yet you were the lead author of a recent study of “Global Trends in the Status of Bird and Mammal Pollinators,” the first assessment of its kind. What prompted you to initiate that study?

I have a background working at the national level in Ireland, doing things like establishing a butterfly monitoring scheme and undertaking invertebrate Red List assessments. When I moved into the international arena, working at [The United Nations Environment Programme’s World Conservation Monitoring Centre], there was a real lack of information on the state of pollinator biodiversity globally. I knew that many countries, like Ireland, had been Red Listing their invertebrate species, so I wondered if we could assess the status of insect pollinators across Europe by looking at different national Red List assessments. I began working with a colleague to see if we could do that, and perhaps look at national Red Lists outside of Europe. Then we thought we could also include pollinating birds and mammals by pulling out the pollinating species from the bird and mammal Red Lists [for which there is much more data].

We ultimately decided that it didn’t make sense to have one paper try to do everything. So we put the insect stuff to the side, and just did one paper on birds and mammals. So yes, as an entomologist I ended up leading a paper on birds and mammals.

Can you tell us a bit about the diversity of birds and mammal pollinators, and give us a few examples?

Over 1000 species of birds and more than 300 species of mammals pollinate. In the tropics and deserts, bats are often the pollinators of nocturnal flowers such as agave, guava, and morning glory. Many species of small birds, such as hummingbirds and sun birds, are pollinators for plants such as orchids and other wildflowers.

Your study revealed that 1.1 bird species and 1.9 mammal species per year move one Red List category closer to extinction, and that the main driver for this trend is habitat loss from unsustainable agriculture. How did you make that connection?

With every species that is assessed for the Red List, the assessors will include what put it under threat of extinction. The information was all there in the IUCN Red List database, but no one had pulled it out in that way. So we did, and then we were able to extrapolate that information.

Can you give us an example of a specific bird or mammal species that has moved closer to extinction, and what the ecological cascading effect has been or is projected to be?

It is difficult to enumerate the impacts of [a particular species decline or extinction] but I would say this about all species: you are taking out parts of an ecosystem, and those parts have roles. With pollinators, the role is clear.

In some cases, a plant requires just one specific pollinator. If that pollinator is lost, that plant may self-pollinate for a period of time, but it loses out on genetic diversity over time and can end up dying out. Habitat needs to be quite large to host a pollinator population [because of pollinators’ mobility and nutritional needs], but plant populations can survive [initially] in much smaller sized habitats. Say one individual pollinator needs pollen from 100 plants a day. If the pollen supply gets down too small, the pollinator won’t be able to survive in that habitat anymore. But the plants will still be there.  There will be a delayed reaction where you’ll lose the pollinators from a patch of habitat, and you won’t realize they’re gone.  Then, down the road, you begin to lose the plants. Insect pollinators are much more sensitive to change than the plants. The same is true for birds and mammals, and they need even larger habitat patches.

Leafcutter bee (Megachile)

There were two mammals in the study that moved in the opposite direction, and became less threatened: the Samoan flying fox & Pemba flying fox. The study attributed this to conservation action. What do we know about that conservation action, and what we can learn from it? 

In the 1980s through the mid 1990s, the Samoan flying fox suffered dramatic declines in Samoa and American Samoa as the result of storms, logging, direct exploitation, and the interaction of these factors. In Samoa and American Samoa, it is principally threatened by overexploitation and forest clearance (logging and conversion to cultivated land). Populations underwent drastic declines in the 1980s. Commercial hunting of the species largely took place to supply the export demand for fruit bats as a luxury food item in Guam and the Northern Marianas. However, this is no longer a threat to the species, because it was listed on Appendix I of CITES in 1990, and international trade in this species is effectively illegal. Hunting of bats for the domestic market appears to have increased in Samoa and American Samoa since the 1980s, and is still a concern today. In Fiji, the hunting of this species is only for local consumption and is not a major threat to the species, particularly on large islands. However, if Fijians either begin to hunt flying foxes with guns or to collect for trade the threat of overexploitation could become serious.

In the early 1990s the population of the Pemba flying fox appears to have been reduced to a few hundred animals at most. In 1997, 94% of the of population was restricted to 10 roosts (of 41 in total) with a total estimate of 4,600 to 5,500 individuals. In 2001 survey work helped to give a more accurate population estimate of ~6,900 bats. The population of bats has continued to increase and by the end of 2006 there were ~19,000 animals. It seems that by working with locals and educating them about the [bat], there’s been a turnaround in the species.

Are there any places in the world where bird and mammal pollinators are thriving?

No. We didn’t look specifically at geographic locations, but when we’ve looked at Red Listing across different countries, there are similar trends coming out. In places like Europe and North America, the trends are slowing down or reversing, but that’s because we have seriously hit rock bottom. At the Biodiversity Consultancy, I work with large companies in developing countries. Although I’m a very positive person, the state of biodiversity in some of those places is quite depressing.

Can you give us an example?

In West Africa, specifically within the poorest countries that are keen on development, there is a lot of mining activity happening and growing, and remnant rain forest is being massively impacted.

Your study mentioned hunting as a threat faced by pollinating mammals that is not faced by pollinating insects. What other threats must pollinating birds and mammals contend with that are not big problems for insects?

Mammals are much higher in the food chain and they have different sensitivities. They could be harder to manage for conservation. As I said, mammal and bird pollinators need much larger habitat patches than insects. Insects are extremely resilient. Many have eggs or larvae that can persist in very difficult conditions for a very long time within the soil. They can multiply in the thousands very quickly. Mammals have a much longer lifespan, longer generation, and they are not as massively resilient as insects.

What do we know about the impacts of climate change on pollinating birds and mammals?

To help illustrate such a mismatch in phenology, I’ll use an example, although it is not a pollinator. In Greenland, when the ice melts, new shoots of grass come through. Before the tannins rise, the shoots are nice and green. Once the tannins rise, the grasses become much more difficult for baby caribou to digest. Well, the snow is now melting earlier, so the plants are growing earlier, and the tannins are rising earlier. But the caribou migration is triggered by daylight length [which has not changed]. So when the caribou arrive, the babies are eating the plants with the tannins in them, and there is now a huge mortality rate in baby caribou. The same kind of thing is happening—although not as well studied–for pollinators. We know that there are mismatches happening all over the place, but we do not know what kind of implications they will have in the long term.

In a 2010 Ted Talk, you said, “We know more about the numbers of stars in the galaxy than we do about the number of species we have on Earth.” How far have we come in terms of knowledge about pollinators since then?

I would say we’re almost as bad off as we were. We are definitely making progress, but too little too slowly. It has got to the point where I wonder whether it’s worthwhile or whether we need to just start going into conservation approaches. Today, the sexy science is genetics. The science of taxonomy is really dying. It has been cut from courses in universities. Students come out with very little taxonomic knowledge. In areas like Africa, there is basic taxonomy work needed, but the skill set is dwindling.

What do you think is needed to get a clearer picture of the global status of all pollinators?

There is a global Red List of bumblebees, and a global butterfly Red List is being developed. But do we need to know everything about all pollinators? Do we need a clearer trend of the status of all pollinators when we know the status of habitats and we know about massive biodiversity loss? Do we actually now need to start doing something about it?

Knowing what we know now, where do you think is the greatest need for pollinator habitat restoration?

If you’re in a developing country, [the greatest need] is habitat conservation. Full stop. In developed countries, you need to remember that insect pollinator conservation can be at a micro scale. This means leaving grassland verges [edges] in towns, or roundabouts that are wild meadows rather than cut grass. Remember that with pollinators, it’s all about having the habitat there for them. We also need to think about corridors. A huge, vast area of America is simply a breadbasket, with nothing at all—not one flower along the way. Insects can’t travel across those distances to migrate or replenish a population somewhere. We must remember connectivity when restoring pollinator habitat.

You and colleagues established global guidelines for standardized butterfly monitoring with the intention of establishing a global butterfly index.  Does that index exist yet, and can you tell us a bit about the guidelines?

The Index doesn’t exist yet, but it’s moving in the right direction. We’re working with the Zoological Society of London (ZSL), which does the Living Planet Index, to bring in butterfly data.

Insects vary from year to year, so it takes a while to get good, robust statistical trends. There is good data for Europe and some parts of North America, and there is data being collected in places like Brazil, Australia, and Israel. ZSL wants to bring in as much data as they can from other places in the world, but it’s going to be a slow process.

If you don’t have comparable methodologies, you cannot bring this data together. In developed countries, people do transects to monitor butterflies. You walk a walk, and for a five-meter box, you record the numbers and species of butterflies you see. But that’s very difficult to do in the dense rainforests of the tropics, where butterflies may be up high or have different seasonality. So there, people use fruit bait trapping to monitor butterflies. We knew we needed a standardized way of monitoring fruit bait trapping, designing fruit bait traps, etc. When we brought everyone together, and said, “Let’s agree on a common methodology so we can bring all of this data together and look at national, regional, or global trends,” we found that there was more commonality among the different methods than we expected.  That was exciting. So it wasn’t like our colleagues in Africa and our colleagues in South America were arguing about whose technique was better. There was, however, a lot of back and forth about the details. There are multiple steps involved in creating a global index, and this was an important first step.

How can our readers get a hold of those guidelines, and how are they being received?

Do you have a sense of the percentage of pollinators that fall into the same category as the monarch butterfly (Danaus plexippus) or the Rufous hummingbird (Selasphorus rufus), which naturally migrate across vast landscapes?

It’s quite small. But even site-specific pollinators will need to be able to move in order to colonize new areas or change in relation to climate change. Corridors for migratory species are one thing, but corridors for the longer-term movement and adaptability of species is very important.

Insects, being the amazing things they are, can actually be very good at traveling long distances across barren areas. The longest insect migration known is that of some dragonflies (Odonata; mostly globe skimmer, Pantala flavescens) which migrate across the Indian Ocean from India to Africa. I have been involved in work on the painted lady butterfly (Vanessa cardui), and we have almost shown that it has a longer migration that the monarch in North America. It migrates from Africa to northern Europe and back again.

Globe skimmer (Pantala flavescens)

Many of our readers are involved in ecosystem conservation and restoration work in a variety of different landscapes at many different scales. Can you offer some pointers on creating and protecting resilient pollinator habitat?

In the urban environment, it’s quite simple: you want to use a variety of native flowering plants so you’ll have sources of nectar or pollen throughout the year, stick with sunny spots, and be sure to think about the different stages of the lifecycles of the pollinators.

For the rural environment and agricultural landscapes, there has been some very interesting work by Bill Sutherland of the group Conservation Evidence here in Cambridge.  They have tested whether or not [different pollinator habitat restoration strategies] have actually been effective on the ground.  They have found that leaving a corner of your field untouched is actually more beneficial to pollinators than planting wildflower seeds.

What advice do you have for practitioners who want to encourage a client client whose primary concern may be an issue like stormwater management to integrate pollinator habitat into green infrastructure design?

There is definitely a feel-good factor associated with pollinator habitat. When you create areas of wildflowers, and you bring in bees and butterflies, no matter what, that increases the aesthetics of the place. In an urban environment, you are also increasing pollination for other gardens and urban farms. For a business owner, putting up signs that say “This is a wildflower area for our pollinators” can be a nice public relations thing.

Working on the butterfly monitoring scheme really [taught me about the importance of] citizen science. Butterfly monitoring happens weekly from April to September in Ireland and the UK. I always encouraged my volunteers just to do the weekly walk in their local area that they do anyway or that easily fits into their routine. When you do that, and visit the same walk every single week, sometimes for multiple years, you really start to understand the life cycles, intricacies, and connections of the butterflies you see. My family and I have discovered new facts about the pearl-bordered fritillary just by doing that.

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