[Field Notes] Grafton Ponds Walk

 Recently I had a chance to take a guided walk with Zach from the Virginia Department of Conservation and Recreation's Natural Heritage Program at Grafton Ponds Natural Area Preserve (NAP). I've talked about Grafton Ponds several times in the past, most recently this past spring when I did a bird walk with some friends.

The walk was in celebration of the 40th anniversary of the Natural Heritage Program and one of several they are doing around the state. Grafton Ponds is special because it has a large number of sinkhole depressions that collect water and then dry out annually. Sometimes called vernal pools or ephemeral ponds, this cycle of wet and dry throughout the year provides good places for amphibian to lay eggs. Fish are one of the main predators on tadpoles and eggs. Since the ponds dry out, the fish can't survive so there are fewer predators for the young amphibians to deal with. There are approximately 200 such ponds in Grafton Ponds complex with about 70 or so in the Natural Area Preserve proper. Depending on the water level, there may be three nearby ponds or a single, larger pond, making it hard to get a precise count. 

The ponds form when water collects and slowly seeps through bedrock that is dissolvable. Often that is limestone. Here on the coast, the bedrock is fossilized shells from a few million years ago, part of the Yorktown formation. Appropriate since the preserve is just outside Yorktown. The ponds continually form as the bedrock is removed and fill in as more sediment fills in the ponds. Zach told us that some of these ponds have been dated to 40,000 year ago while younger ones are around 350 years old. The older ones have a lot of spruce pollen in the sediment dating from the last ice age when spruce could live here. The younger ones formed around the end of a dry era that coincided with the arrival of European settlers. The settlers at Jamestown and other early colonies had trouble finding sufficient fresh water and that is attributed to salt-water intrusion to aquafers due to the extended dry period. As the rains returned, ponds started forming again. The Europeans also removed a lot of trees. The trees pulled up a lot of rain water. Fewer trees means more water to dissolve the shells and make sinkholes.

Some fossilized shells found along a stream bed

Rising With The Tides

They say rising tides lift all boats. Around here they also flood many roads. 

This week we have our first fall coastal storm of the year. It isn't a tropical storm but that doesn't mean we aren't getting strong winds driving up the tides. These are the types of events where flood mapping is particularly important. For the past 9 years, as part of Wetland Watch's Catch the King Tide activity, I've been going out and mapping how far high tides come up onto the land. There are multiple scheduled events each year based on the lunar affect on the tides. But these ad hoc events for storms, or just steady on-shore winds, that drive up the water level are important to capture the weather’s effect on the tidal flooding. 

Today, high tide came just after sunrise so I got up, prepped, and headed out first thing. On my way to my usual first stop I passed this flooded marsh. It passes under the road but get up into people's yards about 100 yd from the creek bank. 

Tides from Sept 24. Data from https://water.noaa.gov/gauges/FTMV2#hg=official

Usually there is a narrow creek here and lots of marsh grass

Not the type of watering you want for your garden

 My usual first stop is a boat ramp near home. Even though the city recently redid the parking lot, the entrance was flooded. After finding a dry place to park, I walk along the edge of the water occasionally recording the precise location in an app. I can record a point without really breaking stride making data collection about as easy as taking a walk. And in many places, I can do it without even getting my feet wet. 

A Good Night and Good Night-Birds

This is the last post about our trip up to the Biggest Week in American Birding (BWIAB) festival. So I thought I would talk about good night-birds, and a good night birding,

One group of birds that I was not expecting to see much at the festival was birds of the night. [Also emus since they don't live anywhere near Ohio.] Therefore, I was pleasantly surprised that we ended up seeing 5 species of birds that are nocturnal.

One of the tours that we signed up for was a woodcock walk at dusk, so we were hopeful of seeing a woodcock. I've been out looking for woodcocks a few times in the past and never succeeded in seeing their aerial display.  I was prepared for us to either not see any birds or the display would be distant and infrequent.

Our woodcock group met up with a couple of guides shortly before sunset. One of the guides told us that the displays had been going on the last couple of nights so he had high hopes. The bird that had been displaying near our spot was showing up as the very last of rays of sunlight vanished. So we had time for the guide to regale us with his guiding stories.