|The Eagle on Galiano Island|
|The following article has used
information, often word for word, from a Government study prepared
by Terri Martin for the (then) BC Ministry of Environment.
|Galiano nests and habitat.
Galiano was found to have 35 bald eagle (haliaeetus leucocephalus) nests in 28 territories. Some multiple nest sites include old nests or alternate sites. Except for the records kept by Dr. Kennedy, historical data is lacking. Human disturbance and animal raids (such as raccoon) can cause a shift in location.
A nest tree may degenerate, and no longer be able to support a nest. Or an eagle pair may decide that encroaching development is too risky to continue nesting in a certain tree. The old tree will often continue to play a significant role in the breeding territory. Usually these trees are dominant, or co-dominant in the area, and they remain valuable perch trees from which the pair can defend their territory. They should not be removed or logged.
difficult to determine if an abandoned nest will be used again. Individual
breeding pairs have different tolerances for disturbance, and land
clearing within the territory.|
Distance from shore.
Usually (in a study of 114 nests) a nest is found to be within 250 meters from the marine shore. The preferred food is fish, but on Galiano in Georgeson Bay, with an incredible seal population taking fish, the diet has at times been noticeably towards gulls. Crow and heron nests can be robbed for eggs, causing anger in the skies, and harassment in turn of the eagle.
Distance between nests.
On Galiano nests are 1 -2 km apart, where suitable nesting habitat is available. Along channels where there is strong tidal action, such as Active Pass, normally producing increased foraging opportunity, nests are closer.
Nest tree characteristics.
Selection depends more on tree height and structure than species. Taller trees, which are usually older, provide commanding perches to watch for food or invaders. Eagles in flight find that nests above the canopy offer better accessibility. Nests are refurbished and repaired each spring by the returning eagles, who will bring to the nest fresh evergreen. Nests can grow huge and heavy, increasing each year. Positioned against the trunk the nest will be supported by one or more branches.
In the Gulf Islands, Douglas fir is preferred, but deciduous trees can be used as a last resort for a nest tree. This happens more on Galiano than other islands because fewer veteran trees remain from logging.
Threats to the nest-site.
Tree cutting is regulated by the provincial Government under the Wildlife Act, and tree cutting right up to the nest-tree is permitted. The Islands Trust has no power to regulate.
Breeding territories are dependent on many habitat components besides the nest tree and on food source - future nest trees, buffer trees around the nest, perch trees, roosting trees, and nearby trees used for nesting material. A single tree in a clearcut is not an eagle habitat.
Most eagle territories in the Gulf Islands have experienced some degree of habitat loss some critical, from coastal land clearing. Development has its highest return from the waterfront ( which competes for values other than purely economic).
In the long term, habitat degradation likely results in increased energy expenditure by the breeding pair. When a favored hunting perch is removed ( and some people ignorantly tidy away dead trees) the breeding pair may have to work harder to find the same amount of food.
If the surrounding patch of bush or trees where sticks are collected for nesting is removed, then the pair must fly further for this task. If the nest is lost it will take more effort and time to rebuild from material further afield.
Removal of buffer trees removes the nest's protection from the elements and exposes it to predators.
To the casual observer the eagles are coping well with these changes, but fragmentation of the nest habitat has its effects over the pair's breeding life-span. Under times of stress such as stormy weather, further nearby development and tree clearing, or years with lower food availability, these territories are far more vulnerable to failure.
Bald eagles have shown remarkable adaptability to human activity, but disturbance thresholds can be crossed. On Galiano, cars used to stop and hoot beside a lone nest tree in a clear-cut, to make the adults fly up for a photograph. The birds remained faithful to the nest but did not breed. Crows and ravens can harass the nest, causing abandonment if it persists.
Location on Galiano.
Nests are located around most of the marine shoreline, with the greatest concentration along the northeast, overlooking the Strait of Georgia. But here, logging by MacMillan Bloedel, although replanted, has not left alternative mature trees should the present site experience damage. In light of the accelerating liquidation of Costal veteran Douglas fir, Section 34 of the Wildlife Act, which protects only existing nest trees, is inadequate. For landowners interested in preserving their eagle habitat, a conservation covenant is a feasible option and may be the only way to offer protection into the future.
Stability of territory locations.
Whenever possible a breeding pair will remain within a territory. They have a long life-span, high degree of bonding, high fidelity to the nest sites, and often occupy a territory for 9 - 10 months of the year, remaining even when there is an early nest failure.
For a territory to remain stable and viable it cannot be stressed enough that the retention of veteran trees around the nest area is of utmost importance. Where no veteran trees exist , then stands of second or third growth Douglas fir must be set aside, hoping these trees will provide opportunities in 70 + years. If all else fails, mature maples could serve as a substandard nest site.
Terri Martin tells us that, although safeguarding the future is a daunting task, when a community is determined a great deal can be achieved (as with most conservation efforts). Safeguarding the nest sites will ultimately determine the future of the eagle.
The waterfront has many values. On Galiano development is carefully placed. But regarding tree-cutting, safeguards are few. Perhaps in time the island will be known for the informed care of landowners and the loggers they employ.