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Raptor nests on Pender Island: A Silent Spring

Updated: Jun 30, 2023

For the first time in at least 25 years, the Shingle-Masthead osprey nest sits empty and silent. Every year, a pair of ospreys have rebuilt their large and complex stick nest on the supporting branch of one of the several veteran Douglas-fir trees along Shingle Creek, overlooking Shingle Bay in Magic Lake. Every year they incubated a clutch of 1-4 eggs; many years these efforts produced young, and many years those young successfully fledged. But never in the past 25 years have the birds returned in the spring, only to abandon this territory without attempting to nest. And so the Shingle Creek valley has fallen silent, devoid of the exuberant calls of the parent and nestling birds that have echoed across the valley each spring and summer for decades.

Massive veteran Douglas-fir growing along Shingle Creek, North Pender Island - a nest site regularly used by osprey. Photo by Erin O'Brien.


Raptors such as ospreys and bald eagles build massive nest structures, with eagle nests weighing in at up to 1000 lb (450 kg). In fact, bald eagle nests are the largest bird nests in the entire world. To accommodate this size and weight, these raptors need large, old trees with huge supporting branches; in the Coastal Douglas-fir ecosystems of the Southern Gulf Islands, this means trees that are 150 or more years old.(1)

Eaglet in large nest supported by a veteran Douglas-fir on North Pender Island. Photo by Kassidy Kelly.


Historical forest harvesting has reduced the supply of suitable nest trees on the Southern Gulf Islands and throughout coastal BC, reducing the number of nesting eagles and ospreys these forests can support.(2) We often hear folks saying, “It’s second growth forest anyway”, implying that it is somehow less important if these forests are lost to commercial logging or large-scale clearing for development; given we are just now seeing veteran trees on the Southern Gulf Islands nearing the critical age and size needed to support raptor nests, perhaps that position needs to be reconsidered.

Commercially harvested 140-year-old Western redcedar on North Pender Island.


Eagles and ospreys are apex predators, occupying a high trophic position in food webs, and are important sentinels of the health of aquatic ecosystems – when they decline, as with other top predators such as the Southern Resident Killer Whales of the Salish Sea, it signals imbalance in the food webs they are a part of. Along with peregrine falcons, these species are of high priority for management and monitoring in both Canada and the US, due to historical declines, low density, high sensitivity to disturbance from human activities, and sensitivity to effects of environmental toxins.(3) In 2022, all but one bald eagle nest on the Penders failed to produce any fledged young(4,5) – a pattern reported to have occurred throughout the lower mainland of BC and elsewhere, appearing to be in part due to the emergence of highly pathogenic avian influenza.(6) While it is normal for nesting success of raptors such as eagles and ospreys to vary considerably from year to year, persistent nesting failures due to the cumulative impacts of multiple stressors (e.g. loss of nest trees due to logging and development, declines in prey such as salmon, emergent diseases like avian flu, low-flying aircraft near nests, climate change-induced cold spring temperatures or heat domes when young are still in the nest) can be amplified and result in long-term population declines.

Commercial clear-cut harvesting of a provincially red-listed forest ecosystem in the Southern Gulf Islands, adjacent to an historical osprey nest site.


Talk to your neighbours. Explain to them that these top predators and their habitats are valued by our community. Rather than seeking the removal of protections for a raptor nest as a condition of sale for a property, new residents should be celebrating the existence of the massive veteran trees that support these nests on the properties they are purchasing. Land value should be increased by the presence of a raptor nest site and advertised proudly by realtors, rather than real estate listings encouraging purchasers to commercially log the increasingly rare veteran trees for a quick dollar. Because when forests of century-old trees are logged now, forest succession is pushed back another century, and with it any chance to restore a diverse supply of veteran trees and the raptor nests that they support.


It is not clear why the Shingle-Masthead ospreys did not nest in 2023; however, supporting branches of the current veteran nest trees in their territory have continued to break off, and there are few large trees emerging as the new veterans that will take their place. Unless we all value and protect the largest, oldest trees we have left, and manage our forests to ensure mature trees are retained to become old-growth in the future, we can expect a future where these apex predators are increasingly rare, and where silent springs are the norm.


Dr. Erin O’Brien

Ecology and Conservation Director

Pender Islands Conservancy



References

(1)Blood DA, Anweiler GG. 1994. Status of the Bald Eagle in British Columbia. Wildlife Working Report No. WR-62. Wildlife Branch, B.C. Ministry of Environment, Lands and Parks, Victoria, BC.


(2)BC Ministry of Forests, Lands and Natural Resource Operations. 2013. Guidelines for Raptor Conservation during Urban and Rural Land Development in British Columbia.


(3)Christophersen RG, Ransom JI. 2022. Osprey, Peregrine Falcon, and Bald Eagle Nesting in North Cascades National Park Service Complex, Washington. Natural Resource Report NPS/NOCA/NRR—2022/2353.


(4)David Manning, personal communication


(5)Pender Islands Conservancy, unpublished data


(6)Nemeth NM et al. 2023. Bald eagle mortality and nest failure due to clade 2.3.4.4 highly pathogenic H5N1 influenza a virus. Scientific Reports 13:191.




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