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Thursday, March 17, 2016

Corvid Course - Class #6 Clark's Nutcrackers, Memory & Whitebark Pines

Our 2016 "Conservation Course" started January 25th.  Below are short-hand notes taken by Raechel Youngberg and a video by CJ Peterson, both class participants.  See notes and videos from the previous classes here:
first class
second class 
third class
fourth class 
fifth class

Class #6 - Clark's Nutcrackers, Memory and Whitebark Pines with Teresa Lorenz & Eireann Pederson
February 29, 2016 

 Watch and listen to the entire class on this video
Clark's nutcracker in Mazama eating suet, by Mary Kiesau
Clark's nutcrackers are named after William Clark of the Lewis and Clark expedition. Clark's nutcrackers are social animals that straddle two worlds. In one world they are similar to other corvids in that they eat a diverse variety of foods but in the other world they are specialists who primarily dine on large pine seeds. They are partial migratory birds, meaning that specific groups migrate to different areas but there still may be Clark's nutcrackers in your backyard year around however they are unlikely to be the same Clark's year around. 

They are gray-bodied birds with black and white wings and tails.  The juveniles have a light gray face and a pink mouth. It is impossible to tell male and female apart based on coloration but it may be possible to do so by observing their behavior. Clark's nutcrackers look similar to northern shrikes, and gray jays.

By Michael Sulis,
Clark's nutcrackers have a large brain for their body size and a large hippocampus, which is one of the main areas of the brain for memory. They have the best spatial memory of any other animal in the world. Clark's store 50-80,000 seeds in caches across a wide area every year. A nutcracker can hold up to 80 whitebark pine seeds at a time in the sublingual pouch inside their mouth, and then carry these seeds for 20 miles before caching them. Clark's can carry up to 20% of their body weight in seeds. During the fall Clark's nutcrackers primarily eat only "stone pine" seeds, preferably whitebark pine, but during the rest of the year they are opportunistic foragers. (Stone Pines are pines that are distinguished by large, dense seeds that lack wings and therefore depend upon birds and squirrels for dispersal across the landscape.  There are five species worldwide.)

Pine trees produce variable seed amounts each year. Some years there is a bumper crop and Clark's nutcrackers will have plenty of seeds to go around but other years seeds are scare and they rely more on other varieties of food. Clark's have been known to eat salamanders, eggs, small birds and frogs. But their primary food besides pine seeds is insects. 

Whitebark pine in the Okanogan NF
Whitebark pine (Pinus albicaulis) was discovered by George Englemann in 1863.  They are the only stone pine (tight closed cone) tree in the Americas. They have large seeds with a high fat content. They rely on animals such as Clark's nutcrackers to distribute them. However Clark's nutcrackers in the Pacific Northwest often prefer to cache seeds in trees rather than in suitable areas for white bark pine to grow, because they need to be able to find them in the winter when snow levels are high.  

Whitebark pine are the 11th longest living tree species on the planet. The oldest whitebark pine was 1,270 years old and nearly a foot in diameter. 

Whitebark pine are high elevation trees (6000-7000ft) and can be identified by their five needles. Whitebark pine's habitat range, not so coincidentally, overlaps with the range of Clark's nutcrackers. 

Whitebark pine cone (Wikimedia)
Whitebark pine take 20-30 years to reach cone bearing age. They then must mature to 60-80 years of age before they produce a large cone crop. It takes two years for a cone to reach maturity, and a whitebark pine will take 3-5 years between cone cycles.   So, it's a slowly regenerating tree.

Whitebark pine are Clark's nutcrackers preferred food. While Clark's nutcrackers are able to adapt to different food sources, whitebark pines are not as adaptable. Whitebark pines are early colonizers after disturbance, and the fire suppression of the west has allowed other trees such as lodgepole pine and other shade tolerant species to easily out-compete them. Whitebark pine also face threats from blister rust (fungal disease that was introduced from Europe), mountain pine beetles, and climate change. 

Whitebark pine was proposed to be listed under the Environmental Species Act (ESA) multiple times. However due to the decrease in the mountain pine beetle population, the whitebark pine was removed from the proposed listing on 12-24-15. Whitebark pine is currently listed as endangered in Canada.

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