AJ- I don't have many occasions to tell this story, but I immediately thought back to a friend and me visiting Antelope Lake in Northern California...it's a reservoir, and we'd walked out on to the earthen dam to a point where a osprey nest was just in view. We hadn't been there recently but knew they'd been there in previous years. After glassing them for a few minutes, we observed activity and surmised that at least one parent was there, and after a few more minutes, saw the other parent return...they switched roles as near as we could tell, and now off the nesting shift the now free osprey soared 'up-wind' but down stream from the dam, then tacked hard to the left towards the top of a stob (what we'd call the dying/dead tree, still standing) and with legs/claws outstretched, at speed with little braking/steering, broke off a perhaps 1" by 20" dead branch, and without much ado, flew back up into the nest with the branch, presumably to complete construction or remodel of their nest.
We both observed this with fairly high powered binoculars without a word until the mission was complete, and then looked at each other in near disbelief... -Don > Date: Tue, 12 Jan 2010 11:15:28 -0500 > From: [email protected] > To: [email protected] > Subject: Re: [ENTS] Projected heights and Jenny's wrath > > That's funny! I've been a birder for more than 20 years. As a climber I > frequently visit the tops of white pine. In my area in eastern > Massachusetts I can very confidently say that damage to tops is > primarily from weather. Over the years I've seen many large raptors > perched in white pine and have never seen them break anything. I've even > seen a pair of Red-tailed Hawks mating in the top of a white pine, you'd > think this rambunctious activity would do some damage but no. I can > imagine perching birds breaking delicate tops on smaller conifers but on > mature white pine for example any branch thicker than an inch is going > to support Red-tailed Hawk (our largest common raptor). I have seen > red-tails intentionally breaking small branches off of red oak for nest > material but they don't seem to go for the uppermost branches when > they're doing this. They need a secure perch on a thicker branch to get > into position to break a small branch. I can imagine a bald eagle easily > breaking out some top branches but their population densities are not > enough in the east to make a difference for our tall white pines. > -Andrew > > [email protected] wrote: > > Gaines, > > > > Oh boy, I hope a rift doesn't develop here in ENTS. Those of us > > obsessed with tree heights will naturally want to limit damage by > > birds perching in the crowns, especially their highest parts. I'm > > definitely not suggesting anyone get out his/her youthful slingshot, > > but in time the temptation could grow. Giving this line of thinking a > > foothold could prompt Jennifer Dudley to establish a bird safety > > patrol to keep a close eye on us measurers. Jenny's wrath would be > > swift and terrible. Resist the temptation Will. Resist the temptation > > Scott, John, Dale, .......... Resist. Resist. > > > > Bob > > > > > > > > ----- Original Message ----- > > From: "Gaines McMartin" <[email protected]> > > To: [email protected] > > Cc: [email protected] > > Sent: Tuesday, January 12, 2010 10:07:42 AM GMT -05:00 US/Canada Eastern > > Subject: Re: [ENTS] Projected heights > > > > Jess: > > > > I had thought about mentioning it before, but when you say that the > > growth rate of a pine tree is influenced by its current height, you > > bring up an important consideration. Strictly speaking it is better > > to say that growth rate is influenced by age, and it is this > > relationship that the growth curves are representing. > > > > But the growth rate/height relationship is something that is too > > often ignored. Years ago I read a report of a provenance trial of > > white oine, that said that the best way to measure results is not the > > height of the trees after some set period of time, but to measure > > their growth rate at various specific heights. The idea behind this, > > if I remember rightly, is that different sites, including microsites > > (my term) influence the early growth of the seedlings differently, but > > this influence is minimized in the data if the growth rates of trees > > are compared when they are at the same heights (comparably > > established, comparably developed). And this kind of measurement would > > best predict the trees’ overall growth potential over time. > > > > Now the data that prompted me to open the white pine growth topic > > showed that the growth rate of white pine on the better sites declines > > more rapidly than that of white pine growing on the poorer sites, so > > much so that after age 55, the growth rates are the same—one foot per > > year. I thought this had some application in the discussion of > > whether or not white pines could, or did grow to 250 feet. Thus if > > the fastest growing pines maintain their relatively fast growth rate > > for only 55 years, then the best growing white pines would not grow as > > much taller than white pines with more ordinary growth rates as we > > might have thought. White pines 100 feet tall in 50 years is good, > > but “ordinary.” Growth of 120 feet is excellent, but after gaining 20 > > feet over the more ordinary trees in 50 years, and maybe a foot or two > > in the next five, no further advantage will be gained. All that made > > me think 250 foot white pines, if view of the fact that none exist > > today, less likely than I might have thought. > > > > Sorry—I said all that before. But I wanted to re-establish the > > context. > > > > Now to the height/growth rate relationship: lost is the above data > > may be the fact that the trees with the most outstanding growth will, > > in spite of any decline in growth rates down to the level of other > > white pine trees after age 55, still be growing faster at any specific > > height. > > > > Of course as Will and others have pointed out, there is the risk of > > storm damage. I would add to that the damage from large bird perch. > > The bird perch issue is not recognized by all foresters, but I have > > observed it first hand many, many times. The tallest trees in my pine > > and spruce stands are the ones usually hit. The new growth is often > > completely mashed down. If this happens early enough in the growing > > season, especially with the Norway spruce, a leader can be > > re-established. I can imagine that slower growing very tall old trees > > would have some difficulty doing that, and the damage could > > accumulate. This would be a significant influence on the ability of > > older, very tall trees to make good further progress upward. > > > > This relates to the ability of second growth stands to exceed the > > growth of trees in the virgin forest. I will take this up in my next > > response. Enough for one post here already. > > > > --Gaines > _________________________________________________________________ Your E-mail and More On-the-Go. 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