Wednesday, August 27, 2014

Real Angry Birds and a Few Other Things of Interest

A not so angry Rose-breasted Grosbeak partakes of some sunflower seed
A lot of us like to think of nature a place of peace and tranquility and not a place where fussing and fighting abounds. Often enough the nature preserve is peaceful, but just lately I've come across a few residents that were not getting along so well. One parent Red-eyed Vireo in particular seemed to be in for a disproportionate amount of strife. It already had a very insistent cowbird fledgling (presumably a foster child), chasing after it and begging for food. If that wasn't bad enough, a pair of Eastern Wood Pewees got onto its case and began diving at it and disrupting its foraging duties. My first thought was that they were doing this in order to drive off their competition, but since vireos for the most part glean their insect prey off of leaves and branches while pewees obtain their insect prey by snatching them out of the air, one would think that there wouldn't be much overlap. 
The parent Red-eyed Vireo (top) and its begging cowbird fledgling (bottom)
An Eastern Wood Pewee - plotting its attack?
When the pewees weren't chasing the vireo they'd be at each other
Imagine being intimidated by something called a "pewee"
The vireo finds its prey (usually insect larva) lurking on leaves and branches
Whatever the reason, the 2 pewees swooped at and chased after the Red-eyed Vireo for the better part of 20 minutes. I finally came to the conclusion that these pewees were youngsters and were likely just having some fun with a smaller species. Interestingly, the vireo would fly off when chased, but then would then come right back and continue its work. There was also an immature Ruby-throated Hummingbird with an inflated sense of its own power. It was chasing everything away including a tanager and that same poor vireo.Why? I can't be sure. Again, there shouldn't be much overlap in food preferences for those species, but go tell the hummingbird that. You might wonder why a comparatively large songbird would "run away" when chased by a crazed hummingbird. Well you might run away too if a giant bee with a sword on the front of its face was heading for you at top speed!
The hummingbird buzzes off after another "victim"
Cedar Waxwings have been very common lately
Waxwings love to take insects on the wing
Local migrants like this immature Chestnut-sided warbler are being seen nearly everyday
An immature Bay-breasted Warbler is a relatively early migrant from the north country
The Nashville Warbler is another local migrant
Baltimore Orioles are only seldom seen locally after August
The Least Flycatcher is yet another migrant songbird that breeds locally

Monday, August 18, 2014

Celebrating 15 years of Beavers

Two of 5 new kits enjoy poplar leaves (July 2014)
This month Spring Farm Nature Sanctuary celebrates 15 years of continuous habitation by beavers. The original pair named Morton & Sarah, set up housekeeping here in August of 1999. During the pair's reign they created 6 ponds, several canals and 4 lodges. From 2001 - 2007 Sarah produced over 20 kits, including Julia, the colony's current matriarch. Julia was born in 2007 and was one 4 kits in Sarah's final litter. 
Morton & Sarah 
Sarah with one of the kits (perhaps Julia?) in summer of 2007
A kit wrestles with Morton
Morton still holds the preserve's record for cutting down the largest tree ever tackled by a beaver on the property. The Aspen tree's leafy crown made a perfect "textbook" landing in the stream. Despite popularly held beliefs, beavers often miss the water when they fall trees. Subject to wind and other factors, cut trees just as often fall away from the stream or pond and they sometimes get hung up in other tree branches and fail to hit the ground at all. However, Morton seemed to have unusually good aim and during his tenure he chalked up quite a decent batting average.    
The biggest Quaking Aspen on the property took about a week to fell
The large tree fell with its crown landing in the stream
The Bank lodge originally built by Morton in 1999 is still in use today
The 2nd lodge that Morton built also saw many years of use
Morton's dam on the 2nd Pond became our longest one, measuring over 200'
Not a pond, but a canal used to transport food and materials between ponds
Morton also built the most dams on the property and managed to construct the colony's most distant pond, which pushed close to the preserve's border. Two of the lodges that Morton originally built have been reused nearly every year. Although both have been renovated many times. The lodge currently occupied by our colony was one of his. 

Revealed by a dam breech - the original foundation stones laid down by Morton at the 2nd Pond dam
Following a major dam collapse that took place at the 2nd pond in 2012, the breech in the dam revealed interesting details of its original construction. I found a neat line of foundation stones that Morton had set in carefully across the stream bed in order to anchor later additions into place. As an animal architect he was unsurpassed. Following a similar dam collapse in 2006, Morton came up with the most innovative patch job that I had ever seen. Instead of making the patch a simple straight line between 2 sections of the dam, he created an oval patch which bowed way in toward the pond side, but also bowed out toward the down stream side. In the center of the oval structure was standing water. 
During the flood in 2006, the gap that opened up in the dam was at least 15 feet wide
Morton's "patented" oval shaped dam patch was quite innovative and it worked! 
Whereas a straight conventional patch would've taken less time, the more complex design served to divert the stream current away from the vulnerable patched area and distribute water pressure more evenly across the dam. Whether or not Morton had this particular design in his head when he set about his task, or if it just naturally evolved during the building process, no one can say. As a testament Morton's workmanship, the next time that same dam broke, it opened up in a completely different place. In subsequent years I've never seen the oval patch design repeated. Morton had at least 6 years of dam building experience at the time that he came up with it and he died the very next year, so the opportunity for him to use it again never arose. All I know is that when other beavers in the colony have been faced with similar dam breeches, they failed to employ Morton's design, and at least in the short term, failed to adequately repair their dams. Granted these instances involved younger and less experienced dam builders.
Morton taking a carrot break
Morton brings some Pussy Willow saplings into the pond - he was a great provider too
Morton (1998 - 2007)
Sarah with a kit in tow
Morton inspects the dam in late fall
Morton's offspring and their offspring continue to bolster the same structures that he began so many years ago

Wednesday, August 6, 2014

Butterflies of Summer & More

Great Spangled Fritillary feeds on Spotted Knapweed
We haven't had the best showing of butterflies this summer, but it hasn't been terrible either. Some species seem conspicuously absent while others experienced a better than average season. For example, Great Spangled Fritillaries have been fairly widespread, while the normally common Morning Cloak butterflies have been hard to come by.Year to year and season to season there are many factors that determine butterfly abundance. Everything from weather to the number of predators, to the condition and abundance of the butterflies' food plants are all important factors. Parasitic wasps certainly take their toll. One of the Baltimore Checkerspot pupae that I had been monitoring ultimately hatched a wasp instead of a butterfly. Obviously an ichneumon  wasp had injected an egg right into the chrysalis. After the egg hatched, the wasp grub destroyed the developing butterfly. Fortunately, checkerspots had a lot of successes this year and could afford some losses.

The Northern Pearly-eyed  belongs to the butterfly family called the "browns"
The outer wings of the Pearly-eyed are replete with eye-spots
Top wings show a different configuration of eye-spots.
A Northern Pearly-eyed sneaks through the honeysuckle branches
The Eyed Brown breeds alongside checkerspots in one of our wetlands
The Common Wood Nymph was quite common in the fields this season
This Common Wood Nymph shows yellow around its 2 prominent eye-spots - an unusual variation in this region
The Painted Lady can be found on several continents
The American Lady has an intricate spiderweb design on its underwing as well as 2 very large eye-spots
One of many hairstreak butterflies found this season
The Hickory Hairstreak was more common this year than last
The Banded Hairstreak was a bit hard to find this season
Hickory Hairstreak in all its subtle glory
Rare now for about 5 years - the colorful Acadian Hairstreak
Baltimore Checkerspots remain the butterfly story of the season, since they were common in all suitable habitat
Nothing subtle about this beauty
A Checkerspot, freshly emerged from its chrysalis, rests on the unopened chrysalis of a neighbor 
The Little Glassywing Skipper on a Heal All flower
The Dun Skipper feeding on Valerian flowers 
The Hummingbird Moth gets nectar from Common Milkweed flowers.
Eight-spot Forester moth feeds on milkweed
Sqaure-stemmed Monkey flower grows along the creeks and in the beaver meadows
Thimbleweed  is one of the anemones that grows in open areas
Buttonbush has been flowering for over 2 weeks in a small wet meadow near our main reforestation field
Royal Catchfly - from a distance it looks to some like Cardinal Flower, but is no relation
Virgin's Bower - a native clematis