Chilling connection between birds and global warming

🕔Sep 22, 2005

Scientific evidence and individual observations point in one clear direction: it’s getting warmer—which is heating up the debate about what to do on a community level.

At a workshop in Prince George last fall, attendees were asked not what is causing climate change, but simply whether they think it’s getting warmer.

Farmers, foresters, biologists, hunters, fishermen, planners and other professionals from communities across northern B.C. agreed the climate is indeed getting warmer, and mentioned earlier spring warming and later, cool fall temperatures.

Notable changes in timing patterns, they observed, include breakup and freeze-up on rivers and lakes, fall logging road closures, and shorter ski seasons. Many of the other examples pointed towards a warmer climate, but the link was more uncertain. This included the appearance of white-tailed deer throughout the region, increasing numbers of migrant birds staying the winter, and one of the largest impacts that we are now facing: the mountain pine beetle outbreak and the increased incidence of other forest pests and pathogens.

Scientific evidence presented at the workshop typically supported people’s individual observations.

The glaciers across the northern hemisphere are rapidly retreating, the average daily temperatures are getting warmer earlier in the spring, and winter temperatures are typically not as cold.

Based on these observations, and an understanding of the factors believed to be causing this warming trend, the information presented also showed that our ability to predict the rate of climate change is improving, and we can now start to make predictions as to what future decades will bring us in terms of rainfall, as well as annual mean and seasonal temperatures.

Although these predictions, like any weather forecasting, have an area of uncertainty, it seems highly unlikely that there is no warming trend. It appears the warming will continue, and will be more accentuated the further north you live in B.C.

The changes are happening relatively rapidly, with the biggest changes having occurred over the last few decades.

Just how this warming will impact us individually and the communities in which we live is less clear. Will our communities remain sustainable if we don’t start to plan and adapt to the ongoing change in climate? Will this change provide new opportunities for our communities?

The uncertainty and challenge of climate change was the focus of this workshop, initiated by the McGregor Model Forest based in Prince George, with assistance from the Bulkley Valley Centre for Natural Resources Research and Management.

If we accept that the climate is changing, predictions could provide communities, businesses and individuals across the North the information they need to plan their futures.

The strongest message and biggest surprise I personally got from the workshop was that the impacts from climate change are not something my children will have to deal with; the changes are happening so rapidly that I and my community have to deal with them now.

For example, once we have logged an area, which tree species or seed stock should we plant if we want to have continued timber supply for our mills and communities in the future? Seed stock and tree species that grow well now? Or seed stocks and trees from a drier climate, that we predict will grow better here in the 10, 20, 40 years from now?

If we plant trees for today, those saplings may die in the future, and if we plant seedlings suited for future conditions they may die now.

In the short term, this conundrum is just as applicable for the plants you may want to establish around your home or to use on your farmland. It will also affect which crops to grow and subsequently which machinery will be needed, and which livestock to nurture.

As the rate and degree of climate change will include uncertainty, we need to become more adaptive in our planning. This may include planting a range of tree species or source stocks, or implementing a range of farming options that will provide an income if the degree or rate of change is different from the prediction.

An example of long-term community planning, which if possible should include the predicted changes in climate, is where to develop future subdivisions. If we know the prediction for a certain area is for increasingly warmer summers and lower rainfall, should we plan to construct a new residential neighbourhood in an area with an increasing fire risk, and/or an area where we can predict that available water supply will decline?

As an example of a winter recreational and tourism perspective, should ski runs be developed further down the slope? What is the projected number of days that these runs will be operational in say 10 years’ time, given the predicted snowfall and frost free days in the future?

As to my own part in this workshop, I was asked to present the likely impacts of climate change on our ecosystems and species.

One of the earlier presentations showed how we can make predictions about the future types of ecosystems that we can expect in the area—if no other ecosystem is already in place. However, the challenge is that ecosystems are in place, and are a highly complex arrangement of fungi, plants, insects, birds, mammals and microorganisms.

Trying to understand how climate change impacts any one of these species—let alone the impacts of this change on the other species in the ecosystem—would be a huge challenge. To further contemplate how climate change may impact the many different species within each ecosystem, and that these in turn will impact many other species, quickly takes us past our ability to predict with any certainty how this change will impact species diversity and abundance within our ecosystems.

As an example, I used my results from a 1986-1996 ecosystem study in the Yukon, where I studied red-tailed hawks. This is a bird that we know relies on small mammals and birds for food.

We therefore expected the strongest impact on its breeding success to be linked to the abundance of its food, and perhaps to the amount of rain in the spring, which is also known to impact the survival of nestlings.

However, we found the main cause of nestling mortality was from attacks on the young by black flies. In addition to causing blood loss and trauma, the flies transmitted a blood parasite. In one year, 75 per cent of the nestlings died and nearly all were attributed to attacks by the flies.

This impact was previously unknown, and from a climate change viewpoint it was of particular concern as black fly hatch is linked to warm spring temperatures, whereas the timing of migration and breeding in many birds is primarily linked to light levels.

If the black flies hatch earlier they will attack the nestling hawks at a younger age, a time when we know they are more likely to die as a consequence of the attack.

A similar impact was also observed in another study of great horned owls. In this case, in years of poor food supply, fledged owls died not directly from starvation, but through its combined impact with the blood parasite carried by the black flies.

How many species of birds are being impacted by black flies? Will birds adapt and breed earlier to avoid this impact?

If we lose species, will they be replaced by other species? If so, how will they fit into the ecosystem food web?

Managers, communities, and planners need good science to answer these questions. There are many new studies underway in Canada and in the world, to better predict the potential impacts of climate change; however, the gaps are very large, and few of the studies are being conducted locally.

The Bulkley Valley Research Centre is working with researchers and managers in northwest B.C. to try and ensure that climate change research is undertaken in local communities and in local ecosystems. This would provide us with the opportunity to respond and, if necessary, adapt as quickly as possible to observed or predicted changes.

The Ministry of Water, Land and Air protection provided seed funding for a research project that that will assess the degree of impact black flies are having on one of our top avian forest predators: the northern goshawk, a species that is the focus of a long-term collaborative PhD study (Todd Mahon) in north central B.C.

However, even with this type of research, it is clear that we will have to plan our futures with climate change uncertainty in mind—to not only try to reduce the negative impacts, but also to look for opportunities it may bring: from plants or trees that we can grow, new or extended tourism markets, hunting opportunities etc.

This workshop was designed to get people and communities thinking about this new reality at all planning levels—personal, business, community and regional—and as a first step to encourage everyone to place all draft plans, which impact or rely upon the environment, beneath a climate change lens. Will this still be an appropriate decision if as predicted the climate will be this much warmer, drier, etc, in this region?

The research community will continue to help in the understanding of how these changes will impact the environment and ecosystems in which we live. However, uncertainty will continue, and we have to learn to adapt to this reality in order to give us the best possible opportunity of maintaining our lifestyles, and to ensure the sustainability of our ecosystems and communities.

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