By Kevin Fraser
They heed no political borders, have no passports, and wing their way across the lines we have drawn on the map. Are they ‘our’ migratory birds? Or are they tropical visitors to Canada each summer?
Lili Chavarria holds a Wood Thrush wearing a light-level geolocator that will track its migration from her nature reserve in Nicaragua to breeding sites in north-eastern North America.
During this particularly cold January in the temperate zone, it is nice to think about our breeding songbirds that have now migrated to lush, humid tropical forest. If you happen to live in the tropics and like birds, you may excitedly anticipate their return each year between September and November. My Nicaraguan friend and colleague Lili Chavarria, often rhetorically asks temperate visitors to her nature reserve (El Jaguar), “Are these ‘your’ birds? Are they ‘my’ birds?” It is not a simple question, because tied up in these musings are not just ‘whose’ birds they are, but ‘who’ is responsible for their conservation.
Some 350 species that breed in North America migrate in fall to the Caribbean, Central and South America. Many of these species likely evolved from tropical non-migratory ancestors. Selection favoured migratory behaviour in some cases because birds were able to avoid the abundant nest predators reducing reproductive success in the tropics and to capitalize on the burst of insect food available in the temperate spring (and the longer day length for foraging). Despite the fact that these birds accomplish a critical portion of their life cycle in North America (i.e. breeding), they are here for a relatively small portion of their annual cycle.
A male Purple Martin outfitted with a geolocator (photo Nanette Mickle).
My Liber Ero-supported research focuses on tracking migratory songbirds year round using new, miniaturized technology (Fraser et al. 2012, 2013a, 2013b). Among other important data, I can determine exactly how long birds spend at different geographic locations. For example, Purple Martins that I tracked from a breeding site in Alberta spent, on average, just 26% of the year (or 95 days) at their breeding site and 47% (174 days) at their overwintering sites in Brazil, with spring and fall migration making up the difference. To get back to the question of conservation, does that mean that Brazilians hold more responsibility than Canadians for the conservation of Purple Martins in Alberta?
The answer of course, is that we need to foster range-wide and international partnerships to protect migratory birds (and other animals) year round, wherever they are found. One of the hurdles is that while the birds do not recognize political boundaries, the funds that can be used to protect them often do. Much of the available funding to conserve migratory birds is for regional projects, not range-wide or full life-cycle efforts.
One pioneering solution to this problem is an Association of Fish and Wildlife Agencies program in the U.S. called “Southern Wings”. Through this program, state funds that would normally have been restricted to protect migratory birds locally, can be applied to conservation initiatives outside of the U.S., either to protect important stopover sites along migration routes or specific wintering sites. The program helps to protect state investment in migratory species and is also cost- effective; migratory songbirds tend to be more concentrated on their overwintering ranges than at breeding sites in North America, thus threats in the tropics can have a bigger overall impact on populations, but so too can conservation action.
A male Golden-winged Warbler captured during its overwintering period at El Jaguar, Nicaragua. This species is Threatened (SARA) in Canada.
To make projects like this work, we need to determine how populations are linked. We are only just beginning to figure out how populations are connected across the vast distances that birds travel. For Wood Thrush overwintering at Lili Chavarria’s nature reserve and coffee farm, we know from our recent tracking studies that some breed in Pennsylvania, which enabled the U.S.-based Southern Wings program to direct state funds to the restoration of migratory bird habitat in Nicaragua.
A Tennessee Warbler on a banana feeder at El Jaguar, Nicaragua. Despite the name, most of this species’ breeding range is in the boreal forests of Canada.
What about birds that breed in Canada, but winter in the tropics? This category includes 38% (or 171) of our 451 bird species, many of which are species at risk. Currently there is no formal government program to fund the conservation of Canadian-breeding Neotropical migratory birds and their habitat once they leave our borders. Considering that breeding birds like Purple Martin are in Canada for just 26% of the year, conservation effort employed only within our borders will have limited success. Clearly, there is critical gap in our conservation efforts for long-distance migrants, and we desperately need programs like Southern Wings in Canada, with important links to our Species At Risk Act.
Kevin Fraser with Lili Chavarria and her husband Georges Duriaux. Their coffee farm and nature reserve in the cloud forests of Nicaragua can be seen in the background. This site provides rich overwintering habitat for birds that will migrate to Canada, like Wood Thrush, in addition to preserving habitat for hundreds of tropical resident species.
For now, birds that migrate to protected areas such as Lili Chavarria and George Duriaux’s El Jaguar reserve in Nicaragua are some of the lucky few that may survive to breed another season in North America. For the future, we need to collectively work to make the connections and establish the programs that lead to full life-cycle conservation of our migratory species at risk.