The Hunt for Red Knot

For the second time in three years, I journeyed to the Delaware Bay beaches of New Jersey in search of the red knot, a long-distance voyager from South America. In 2019 I spent a day scouring Cape May County and while I had a great day of birding, I was unsuccessful. I decided to try again in a year, spending a few weekdays on vacation there to have 24 hour access to the beaches while avoiding the weekend crowds. That trip was cancelled because of Covid, although I'm sure the shorebird migration was unaffected. This year I was able to make the trip, giving myself a Sunday, Monday, and part of Tuesday to find the elusive little sandpiper.

Red knot (USFWS)

Sunday, May 23rd was one of the warmest days of the year so far. I wasn't in a rush to get anywhere so I wasn't on the road at the crack of dawn, but I didn't want to waste any daylight. Leaving by 7:30 was a good compromise. I made great time getting to the beaches in the area of Villas, NJ. Two years ago my first stop was Kimbles Beach, a part of Cape May National Wildlife Refuge. I decided to stop there first again. There were laughing gulls and "peeps", a generic term for the little sandpipers that all look alike to me. They weren't present in as great a number as 2019, and it could be because this year's trip was a little later in the migration than before.

Peeps and gulls feeding at Kimbles Beach

The tide was on its way out, and there were quite a few horseshoe crabs on the beach, and pearly green eggs in the wrack line. Some were making their way back into the bay, while others were burying themselves in the sand. Still more were dead, becoming meals for the birds and other critters. I scanned up and down the beach, but no red knots. There was a volunteer naturalist on duty, and she told me to check back later in the day when the tide is coming back in, about four in the afternoon.

Horseshoe crab eggs

It was late morning, so I had quite a bit of time to kill until then. My next stop was Higbee's Beach, where I saw my first American oystercatcher two years earlier. This time there were more people than birds on the beach so I didn't spend much time there. The highlight of this beach was a whelk egg case that had washed ashore.

Whelk egg case

The clock was still slowly ticking away until the tide returned, so I went to Fire Control Tower #23, a World War II observation tower. It was lovingly restored and opened to the the public for tours while I was living in Washington, and in 2019 I arrived just after it closed for the day. I was determined to get inside this time after years of wondering what was in there.

Skipping over the history lesson and staying on track with nature, the real reason for my visit, I had a picnic lunch at Cape May Point State Park before hitting the trails there. The trail I chose was a loop through a maritime forest and around a freshwater pond. Swans and ducks were beating the heat with a swim, songbirds serenaded me, and the air was scented with saltwater, bayberry, and eastern red cedar. Some wildflowers added a splash of color, and a muskrat lodge was the only sign of mammals. By the lighthouse, a flock of purple martins flitted around their little hotel on a pole, calling to each other and snagging insects like little flying acrobats.

Muskrat lodge

I checked in at my AirBNB just a block from the bay and took a nap until it was time for the tide to return. I went back to Kimbles Beach and waited. The horseshoe crabs were still there, and in greater numbers. The laughing gulls and peeps were still there, but no sign of red knots. A few other people came to the beach and we talked about wildlife for a while. I was scanning to the south and Liz, a birder from North Jersey, was scanning to the north. She spotted the red knots in a mixed flock. Finally, after two years I got the bird I was after. Much like the first time seeing the horseshoe crabs spawning, it was a surreal experience.

Horseshoe crabs coming ashore to spawn

A mixed flock that includes red knots

Seeing the red knot on the first day freed up the rest of my time to look at other wildlife areas. I went to Sunset Beach, hoping to catch a glimpse of Mercury and Venus after sunset, but the clouds had already come in by then. I spent some time at the gift shop and got a few items for my friends while I waited for the traffic situation there to clear out, then got some nighttime lighthouse pictures.

Monday was cloudy, drizzly, and about 30 degrees cooler. I wasn't about to let a few raindrops ruin my day. A rainy day at the beach is better than a sunny day at work. After breakfast in Cape May, I went to the Nature Conservancy's Garrett Family Preserve. It's a small property in between a residential neighborhood and Cape Island Creek. The property is a matrix of forest and field up against a salt marsh. I saw and heard quite a few songbirds, a young rabbit, a baby diamondback terrapin, a duck, a turkey vulture, wildflowers, a pile of feathers and bones, and some bee hives. In the salt marsh, there was an osprey on the nest and a bunch of holes where I saw some kind of motion. It was fiddler crabs scuttling back into the holes when they saw me coming.

Baby diamondback terrapin

My next stop was South Cape May Meadows, another Nature Conservancy property on the Atlantic. I first went there in 2019 and had a great day of bird watching. This time was more of the same, despite the drizzle. I saw my first glossy ibis and more turtles. However, it was just turtle heads poking out of the water so I couldn't tell what kind they were. There was another muskrat lodge, swans, ducks, geese, terns, and peeps. On the beach in the fenced off nesting area there were terns, oystercatchers, and some other bird that was too far for me to identify. I came across a toad, lots of feeding peeps including dowitchers, otter scat, and more piles of feathers where some bird met its demise. 

Long-billed dowitcher

Beach toad

Glossy ibis

A walk around Lake Lily brought me pond lilies, a robin fledgling, and a family of swans. After a late lunch I went to the wildlife refuge's Two Mile Beach unit on the Atlantic outside of Wildwood. While I didn't see them, there are snowy plovers nesting there. By the time I got there, the rain became steadier than a drizzle and the dark clouds and high wind made for an angry looking ocean. I continued walking the trails. More ducks and peeps, my first eastern towhee, and my first yellow warbler were waiting for me.I decided to head back to the bay to see if the red knots would be back with the rising tide. But first, I had to hit the boardwalk and grab some more gifts. Bubble blowing unicorns are in, license plates with your name are out.

Kimbles Beach was getting a steady rain when I arrived, but the wind was gone. Despite the incoming tide, the waves were almost nonexistent. So were the crabs. And so were the red knots. I decided to order dinner and call it a night. I had one last stop planned for Tuesday before going home, but my GPS wanted me to drive around a trailer park so I just left. One of the last things I saw before leaving New Jersey was a great blue heron flying over the Delaware River. 

The plan for finding the red knot worked. I avoided weekend traffic for the most part, I slept in an ideal location, the weather was mostly cooperative, I learned a lot, and saw a blend of new sites and old. I saw close to 30 different bird species, 5 that I never saw before, including the one bird I went to see. My long weekend was a nice break from the office and recharged my batteries for me, in spite of the miles I put on my feet.

Species of the Month

Halloween is just around the corner. Traditionally, we examine a spooky critter with a connection to Halloween for the Species of the Month. This year let’s try something different. There’s nothing scary about a ghost crab, but its name fits the season. 

Ghost crab (Science Magazine)

Scientific name: Ocypode quadrata 

Kingdom: Animalia (animals)

Class: Malacostraca (soft-shelled crustaceans)

Order: Decapoda (ten-footed crustaceans)

Range: Rhode Island to Brazil 

Habitat: Ocean or estuary beaches, from the tide line to the dunes 

Lifespan: 3 years 

Diet: Bean clams, mole crabs, sea turtle eggs and hatchlings, organic detritus 

Predators: Shore birds, gulls, raccoons 

Conservation status: No special protection

Other info: Ghost crabs are small, nocturnal crustaceans. They grow to about a two inch carapace (back shell) with long legs and eye stalks, and their claws are uneven sizes. Ghost crabs hatch from an egg in the ocean and go through six larval stages before developing into adult crabs. Unlike other crabs that can only mate when the female is molting, ghost crabs can and do mate at anytime after reaching maturity which is usually after a year old.  

Juvenile ghost crab (NPS)

Ghost crabs live in burrows in the sand. They plug the holes during the day and emerge at night for feeding and mating. Mating occurs near the male’s burrow. They travel several feet per night and may not return to the same burrow. Occasionally they will go into the water to wet their gills; they are also capable of absorbing water from the sand into their gills. 

Ghost crabs can be used as an indicator species to monitor the health of their habitat. Populations can be easily estimated by counting burrows. Knowing the status of the crab population can tell what kind of impact human activities are having on the ecosystem overall. Off road vehicles and coastal development are the biggest challenges we give them. 

A pair of ghost crabs (NPS)

Once again this week's information comes from the Animal Diversity Web at University of Michigan. Next week is a rerun. We'll have fresh content after Halloween. Stay tuned!

Getaway Islands

Summer is here and for many people it's the perfect time to relax at the beach. If you're at an East Coast beach, odds are you're on a barrier island. The Atlantic barrier islands extend from Canada to Florida, then up Florida's Gulf Coast and all the way around to Mexico. Prior to development, many of these islands came and went at the whims of the tides and storms. Now that we've built homes and resorts on them, there is a vested interest to make them more permanent by using jetties to block the outflow of sand and beach replenishment to restore what's been lost. Let's take a look at the natural history of where you built that sand castle.

Grassy dune in New Jersey

Barrier islands, if left to nature, live and die by the tides. Ocean currents carry sand away from the islands. The sand either moves out to the sea floor, where it can be brought back to the island by currents, or it is carried to another part of the island or to a different island. Strong storms can accelerate the process, wiping islands off the map or opening up a new inlet to the back bay.

Hurricane Irene cut these inlets across Hatteras Island (NOAA) 

Barrier islands can move toward the mainland as wind blows sand over the dunes to the bay side. The marshes fill in with sand and build up new dunes, while ocean moves to where the dunes originally were and new marshes form in the bay on the edge of the old marshes.

Salt marsh at Assateague Island (NPS)

The islands are important because they are barriers protecting the mainland from such storms. A few weeks ago we looked at hurricanes on this blog. Barrier islands absorb the brunt of the storm surge that comes in ahead of the hurricane. Developed barrier islands still absorb the storm surge, but not as well as undeveloped islands from times past. Impermeable surfaces like roads and parking are terrible at absorbing water, while sand drains quickly. If the dunes have been removed from an island, the storm surge rushes right over top with nothing but buildings to slow it down.
Barrier islands are also important as habitat for critters other than summer vacationers. On an undeveloped island, different plants and animals that can tolerate different amounts of salt water and exposure to the air make their homes in different zones. Clams live beneath the sandy shore, while birds that prey on them scurry above. Grasses hold the dunes in place, and at the highest points of the island you can find trees and shrubs where songbirds and mammals live. Brackish marshes on the other side of the dunes host crabs and serve as a nursery where fish can eat and grow before venturing into the open sea. Wading shorebirds take advantage of this bounty. Beyond the marsh is the back bay and the mainland.

Ghost crab (NPS)

Sandpiper feeding frenzy

The US has more barrier islands than any other country in the world. Best known are New York's Fire Island, Texas's South Padre Island, the Outer Banks of North Carolina, and the Jersey Shore. If you spend a summer weekend at the beach, be sure to check out the wild side of things.
This week's information comes from Science News for Students.

Everglades Ecosystems

This week and next we’re taking a look at the largest subtropical wilderness in America, the Everglades. What we now know as Everglades National Park is just a fraction of the original Everglades, and unfortunately, almost daily it becomes a larger percentage of what of remains today. While what remains is an incredibly diverse variety of habitats, each with their own plants and animals, it is not without its challenges. We’ll explore what’s so special about this place as well as what’s going wrong there.

In its former glory, the Everglades was a huge watershed. Water flowed south from areas north of Lake Okeechobee and drained to the east, west, and south. Some of the water flowed east and west into the Atlantic Ocean and Gulf of Mexico, respectively, through traditional rivers and streams. Some water flowed out through the slow-moving “River of Grass”, as the Everglades became known as. Where the water goes and how much gets there determines the many different ecosystems.

Many other factors go into building an ecosystem, including geology and climate. To me, what gives an ecosystem its character is its plant life. The Everglades has quite the cast of characters, with grasses inhabiting the freshwater sloughs and marl and coastal prairies. Marl prairie is grassland of thin soil formed on top of limestone bedrock. The soil is high in calcite and the bedrock may be exposed in some areas. Rainwater becomes acidic as it dissolves plant material, and even a weak acid can easily dissolve limestone. The bedrock here is very porous. Marl prairies drain slowly.

Marl prairie (Florida Museum of Natural History)

Freshwater sloughs are main arteries for water flowing to the sea. The water moves very slowly and is very grassy. The sloughs are dotted with “islands” of trees and are bounded by the higher and drier marl prairies.

Freshwater slough (NPS)

Mangrove forests line the channels and rivers in the coastal and estuarine areas of the Everglades. Mangroves buffer the coast from storms, collect sediment to form new land, and harbor a vast array of birds, reptiles, mammals, and fishes. See my earlier blog post for more details.

Mangroves (NPS)

Hardwood hammocks are dense wooded areas on slight rises. Temperate and tropical tree species mingle here, and because the surrounding lowlands are either wet or not land at all, fire rarely reaches here. The dense canopy creates a dark and humid environment where ferns thrive.

Hardwood hammock (NPS)

Pine rocklands form on high ground around exposed limestone bedrock. These forests are less dense than hardwood hammocks. Fire keeps the understory open and hardwoods at bay.

Pine rockland (NPS)

Marine areas of Everglades National Park also have plant communities. Seagrasses stabilize the bottom, trap sediments, provide a nursery for fishes, and feed underwater herbivores. Lobsters, crabs, shrimp, corals, and sponges are also found offshore.

Florida Bay marine habitat (NPS)

Next week we'll look more at the plants and animals of the Everglades, as well as challenges the region faces. Information and photos this week come from the National Park Service.

Road Trip Adventure- The Crabs of Delaware

The horseshoe crab is possibly the most bizarre critter you will encounter on a sandy Atlantic beach. Resembling a helmet with legs and a tail, they are not actually crabs at all, but are more closely related to spiders. They are nearing the end of their spawning season, and I traveled to Delaware to get some time in the field and see for myself.

Horseshoe crab (left) and traditional  Dungeness crab (right)
side by side for comparison

Horseshoe crab undercarriage

These marine arachnids are an ancient species dating back over 300 million years. I’m sure they’ve been spawning since then, but unlike most sea creatures, they come ashore to lay and fertilize eggs. Mid-May to early June is prime time for spawning. The crabs haul ashore at high tide and they prefer full or new moons. I just happened to arrive a day after full moon, so the event was in full swing when I got there. Check the video raw here. 

Horseshoe crabs spawning at midnight

Males are smaller than females, and will climb on the backs of females to fertilize the eggs as they are released. There are more males than females, so sometimes there will be one or two “satellite males” clinging to the sides in addition to the first male to attach. Females lay a few thousand eggs per shot, and will emerge to spawn several times over the course of the season.

She’s laying that many eggs for good reason: there are tons of migratory and seasonal shorebirds on the coast looking for a quick and easy meal. Eggs and freshly hatched larva really hit the spot. Eggs hatch after two to four weeks. Larva hang out in the shallow water for a few years, while the adults return to the briny deep.

Horseshoe crab returning to sea

Walking the beach the day after watching the midnight spawning, there were a few stragglers. In some cases, all that remained were the crab tracks. The shell plows a path in the sand that ends in a horseshoe shaped depression (or a crab, if it hasn’t made it back to sea yet), which is how the crab got its name. There were also a few dead ones that were stranded after the tide went out. 

Leaving behind a crab track

Seeing a live horseshoe crab for the first time was an interesting experience. I’m not a diver so my only in-person encounters with marine life has been tidepool critters that don’t move, such as a sea anemone. Getting down to the beach and turning on a flashlight and seeing all those crabs together in a writhing, tumbling mass of helmets was incredible. If you ever get the chance to watch, I highly recommend it. Just remember to leave no trace. I picked up about 2 ½ gallons of garbage before leaving.

Nature Minute now has a Youtube channel! I will add videos as I feel like making them. In addition to the video linked above, there are others from my weekend adventure in Delaware. Next week I'll have some stories from the road.