Thursday, October 30, 2014

Reassessing the Raytharn Farm Grasslands

Between a pasture and a crop circle
Since 1997, the Pennypack Trust has been working diligently to create habitat for meadow-nesting birds which, as a group, are the most endangered suite of birds on the East Coast because of habitat loss.  Our strategy has been to establish native, warm-season grasses on the 160-acre Raytharn Farm we purchased that year.  Now nearly two decades into the project, we have a fairly respectable stand of native "prairie" grasses cloaking the land.  The grasses are beautiful (especially this time of year), resilient, and very popular with our visitors - but not with the birds we are trying to attract.  Eastern Meadowlarks, Bobolinks, and several species of sparrows stop in the grasslands during migration, but they never stay to breed.  What's wrong?  Didn't we do everything right?

Well, it turns out we didn't do everything right.  Grassland managers all along the East Coast have come to realize that the birds are seeking diversity - diversity in height and diversity in plant composition.  To the birds, our grasslands are too dense, too tall, and too monotonous, and they don't provide food (i.e., insects) in sufficient quantities for nestlings.

So, you might recommend that we diversify the grasslands, and you'd be right.  However, we also have a terrible problem with invasive plants.  The grasses can be treated with special herbicides that kill all invasive plants except the grasses, but there's no such "magic bullet" for diverse combinations of plants.  Once invasive plants colonize a mixed-vegetation meadow, control becomes much more time consuming and costly because the invasive plants have to be removed "surgically" without disturbing the desirable plants.  We've resisted trying to diversify our grasslands for that reason.

But, we've finally come to the realization that (1) we're not going to attract meadow-nesting birds if we don't do something different, and (2) if we can't attract meadow-nesting birds, why have the grasses at all because our landscape really wants to be a forest and we have to fight Mother Nature (i.e., natural succession) to keep it in grassland.

Fortuitously, I recently ran into Roger Latham, a respected field ecologist.  Roger and I are good friends, and he has visited Pennypack to consult on several occasions.  He also served on the board of directors of the Natural Lands Trust (NLT), which has preserves all over southeastern Pennsylvania and southern New Jersey.  He told me that NLT's Gwynedd Wildlife Preserve near Ambler had had Eastern Meadowlarks nesting in its native grasslands this summer, and he suggested that I talk to Gwynedd's land manager for some guidance.  So, I rounded-up Pennypack's senior stewardship staff for a field trip and we paid a visit to Gwynedd on October 30.  
Edge of the "crop circle" (darker foreground), native grassland (tawny center) and pasture (green, far left)
Tom, Gwynedd 's land manager had successfully created native grasslands like we had, but had also failed to attract meadow-nesting birds.  Then, he decided to create "crop circles" - round meadows within the grasslands that he seeded with a mixture of 16 different species of low-growing flowering plants (i.e., wildflowers).  Three years ago, he established about 10 such circles ranging in size from 0.25-acre to over 4 acres.  And, this summer, Eastern Meadowlarks nested in his preserve - not in the crop circles (and not in the native grasses), but in a pasture composed of non-native grasses immediately adjacent to the largest crop circle.  
Diverse crop circle vegetation (foreground)
Tom watched the meadowlarks build nests in the pasture (which is just as monotonous a monoculture as the native grasslands, but lower in height).  Then he watched the adult birds fly into the crop circle to catch insects that were using the wildflowers.  Success!
Crop circle (foreground), native grasslands (mid-ground), and woodland (background)
Tom's crop circles get colonized by the same invasive plant species with which we have to contend, but he told us that he is able to control the invasives before they become problematic with a combination of mowing before the invaders set seed, spot application of herbicide, and the judicious use of a string trimmer.  He's got a smaller land stewardship staff than Pennypack does, so Pennypack's staff should be able to do as well.
Crop circle (right) and native grassland (left)
Pennypack's staff drew-up plans for the Raytharn Farm grassland modifications in the car on the way back to Pennypack.  Stay tuned; it may be a year or two before we're successful, but at least we now have a plan!
Autumn color in the Gwynedd grasslands
 Submitted by David Robertson
 Executive Director

Wednesday, October 15, 2014

Moon of Falling Leaves Ramble

All eyes (image borrowed from an Internet source)
The sky cooperated beautifully for our postponed-because-of-rain Full Moon Walk on the evening of Wednesday, October 8, giving 15 walkers great views of the moon and some interesting checkered patterns created by the subtly illuminated clouds.  Also, while it was a bit breezy, the temperature was perfect for the walk - mid 60s.

As I was leaving the office for the day a few hours before the walk, I mentioned to a co-worked that I had to lead the walk and that I'd have to make sure that none of the walkers tripped in a groundhog hole in the dark.  Well, none of the walkers fell into a hole, but honest to goodness, I did, and I went down on my back.  Boy, did I feel stupid, but nothing other than my pride was hurt.

In an effort to spot something during the walk, I shined my strong flashlight into some of the meadows alongside the trail on Raytharn Farm.  No deer, coyotes, or foxes, but the light did reflect off a tiny "something" in the grass.  It was a pinprick of brilliant green light.  I left the trail, keeping the light shining on my "quarry" all the while.  When I got right up to the spot, the reflection disappeared (the angle of the light had shifted so the pinprick was no longer reflecting anything).  I searched and searched, but couldn't see anything until I finally spotted a wolf spider among the grass.  Sure enough, its eye(s) were reflecting green.  Cool!  After I spotted the first spider, we started to see them everywhere.

Near the end of the walk, I shined my light into an open meadow often favored by deer.  We saw two green eyes burning back at us.  The eyes blinked, and then whatever it was walked away.  The eyes were forward-facing; I suspect they were a fox or coyote rather than a deer.

Everyone seemed satisfied by the walk even though we didn't see any animals (we're too noisy), hear any owls, or observe any constellations because the sky was too bright from the reflected lights of the city.  Most people just seemed to enjoy the light of the moon reflected like quicksilver on Pennypack Creek  and walking outside creating their own moon shadows.

Submitted by David Robertson
Executive Director