Wildlife Interactions

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Clark’s Nutcracker

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Squirrel

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Black Bear (drawings by Andrea Coates)

 

Nutritious whitebark pine nuts, high in protein and fats, are a favourite food of  the Clark’s nutcracker, red squirrels, and grizzly and black bears.

Whitebark Pine and Clark's Nutcracker: a Reciprocal Relationship

Whitebark pine is the only stone pine in North America, meaning that its cones do not open when the seeds are ripe.  The mechanism of cone opening and seed dispersal is neither serotinous (by fire) nor by wind, but dispersal by Clark’s Nutcracker (Nucifraga columbiana).  This relationship was thought to be mutualistic, that both species depended on each other, the tree for seed dispersal and the bird for the seeds as a food source, but evidence suggests that while whitebark pine does rely on the Clark’s Nutcracker as its primary seed disperser, the nutcracker will eat other coniferous cone seeds, insects, spiders, small animals and carrion.

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The study area surrounding Smithers is the northwestern extent of the known breeding range of the Clark’s Nutcracker.  Near the Takla Range in north central BC is the northeastern extent.

With the decline of whitebark pine, there is a concern that seed dispersal within those stands will disproportionately decrease and that nutcracker populations may also decrease. Recent studies in the Crown of the Continent ecosystem, centered in Montana, indicate that nutcrackers do not reliably disperse seeds from highly damaged whitebark pine communities.  A drop in seed production reduces nutcracker visits, thus also seed dispersal, resulting in reduced regeneration.


The Bulkley Valley Research Centre conducted a pilot study over the summer and fall of 2011 to investigate Clark’s Nutcracker use of whitebark pine stands and the health of those stands at the extent of their breeding range.

The objectives of this pilot study were to:

(1) determine if and how Clark’s Nutcracker use whitebark pine communities at the northern extent of their range

(2) estimate Clark’s Nutcracker density in whitebark pine habitat

(3) assess stand health and cone production in northern whitebark pine stands frequented by Clark’s Nutcracker.

Three transects were established (Eagle Pass, Kidprice Lake, and Hankin Plateau) for this study and these sites were visited at least twice during the breeding season, after chicks had fledged.

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Two Nutcrackers extracting seeds from whitebark pine cones

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Clark’s Nutcracker research transects

Study areas were chosen based on the amount of healthy whitebark pine, stand size, and accessibility.

All nutcrackers observed per transect (stand) were located with binoculars.  Collected for each observation were: nutcracker activity, the tree species where it was observed, presence/absence of cones, and general health of the tree.

At Hankin Plateau, pairs were seen along the transect in July and August 2011.  On August 2, 2011, one large fledlging was recorded during the survey being fed from caches by both adults.

At Kidprice Lake, pairs were seen in the area in July, 2011.  One individual was observed for 1.5 hours while it fed in the vicinity of the transect. Most notably, the bird was recorded flying across the lake to the 2004 Nanika wildfire after feeding on cones. The bird was not directly observed caching seeds, but was seen returning to the whitebark transect. In Sept. 2010, observers recorded whitebark pine germinants at seed cache sites in this same burn. No fledglings were confirmed in this study area.

At Eagle Pass, individual nutcrackers were seen at visits in July and early August, 2011.  No pair behaviour or fledglings were noted.  In late August 2011, 2 flocks of nutcrackers (numbering approximately 15 and 25, respectively) were recorded during a survey, indicating the start of migration behaviour.

Unfortunately, during transect surveys conducted so far, not enough data was collected to calculate density of Clark’s nutcracker along the transects in the study area.  However, given that breeding pairs, fledglings and larger flocks were all seen in the study area around Smithers, it should be possible to track nutcracker numbers to record trends and share data with other research projects.

Read More

Research publication (McKay and Krakowski 2014)

 

Red squirrels

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Squirrel bites on immature whitebark pine cone, Kidprice July 2011

Red squirrels compete with Clark’s nutcracker to harvest and cache all of the whitebark pine cones, often removing all of the cones before they are ripe.  They will also attempt to break into cone cages to remove the few remaining cones.

Red squirrels fiercely defend their caches (middens) of whitebark pine cones from other small mammals, but they are often raided by black or grizzly bears.

Bears

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Bear claw marks on whitebark pine, Kidprice, July 2011

Many of the cone-bearing whitebark pine trees at Kidprice Lake have been climbed by bears seeking the cones.  

Click and scroll down to bottom to view a video of Boo, a captive grizzly bear eating whitebark pine seeds