Tropical Avian Visitors to New Jersey

Scarlet tanager

Each spring, birds known as “neotropical migrants” make incredible long-distance journeys to breed and raise young. Spending winters in Central, South America and the Caribbean and as far as the tip of South America.

Bird watchers are on thelookout in the spring for these birds as they head north to breed and are passing through New Jersey.

Spring in North America means plenty of emerging insects and places to nest. Longer days and seasonal abundance of food, means long-distance migrants can raise larger clutches of young than their tropical relatives who stay put.

Many species follow coasts or natural features like rivers and mountain ranges. Most birds that migrate to or through New Jersey follow the Atlantic Flyway, an avian superhighway that includes all of North America’s Atlantic coastline. Birds also navigate by using the position of the sun and stars, sensing the earth’s magnetic field, and noticing landmarks during the day.

Red knots fly from the tip of South America to the Canadian arctic, and are known for making a critical stopover along the Delaware Bay in New Jersey to fatten up on horseshoe crab eggs, which give them the energy to complete their journey.

New Jersey has many great locations where birds can either pause along their migration routes or stay for the summer to nest and raise young. According to the New Jersey Department of Environmental Protection, we have 361 species of neotropical migrating birds, including warblers and shorebirds. Over 130 species nest in New Jersey, and nearly 80 of those are songbirds such as wood warblers, a group of 36 species that includes yellow, black-and-white, cerulean, northern parula, prairie, pine and Cape May warblers. 

Another group of neotropical migrants are the brightly-colored tanagers and orioles, including the scarlet tanager and Baltimore oriole. And then there’s eastern North America’s smallest bird, the ruby-throated hummingbird, which winters in Central America and breeds throughout the eastern United States and southeastern Canada.

Among New Jersey’s many birding hotspots are Cape May Point State Park, the Sandy Hook unit of Gateway National Recreation Area, the Great Swamp National Wildlife Refuge, Sourland Mountain Preserve, Stokes State Forest, High Point State Park, and Liberty State Park.

Ruby-throated hummingbird

SOURCE

Bat Migration and Hibernation

When we think of migration flights by some species, birds are probably what we are thinking about. But bats also migrate. During these migrations, they will often rest in odd places - window screens, exterior walls of homes and buildings - and will frighten humans.  

Silver-haired bat found in Newark - Photo: K.Perotta via NJDEP 

They are often alone and may remain for a day or two. They are not harmful or threatening to humans and should be left alone. What you should do is take a photo and send it to  MacKenzie.Hall@dep.nj.gov with information about the location and date. The Endangered and Nongame Species Program (ENSP) is able to catch some of these migrating bats in mist nets and then use nanotags to track them for a few weeks to learn about their patterns. Your photos and information can supplement that data. Even if you don't know what species you have found, take several photos from different angles and send them for identification.

Hoary bat found in Avalon - Photo: M.Wright via NJDEP

New Jersey has had an active bat conservation program for many years that has a focus on protecting winter dens of non-migratory species that gather together for hibernation. These winter colonies often number in the hundreds or thousands. Bats are especially vulnerable to disturbance and vandalism during hibernation. Even unintentional human activity can arouse the bats and cause them to use up their energy reserves too quickly. 

The Hibernia Mine in Rockaway Township, Morris County is our most famous "bat cave" or hibernaculum. The site had been used for mining iron ore from the early 1720s until operations ended around 1913. Bats were first observed in the abandoned mine in the 1930s, and by the 1980s more than 20,000 bats were wintering there each year. But vandalism and trespassing were big problems. When federally endangered Indiana bats were found to be using the mine in 1992, New Jersey acquired the property soon thereafter via the Green Acres Program and it is now part of the Wildcat Ridge Wildlife Management Area.

The hibernating colony climbed to around 30,000 bats in the early 2000s, with Little Brown bats being most numerous but bats of all cave-hibernating species seeking refuge there. Sadly, White-nose Syndrome hit Hibernia in January 2009 and more than 90% of the bats died.

For more on NJ bats: state.nj.us/dep/fgw/ensp/bat.htm

Horseshoe Crabs Come Ashore from the Delaware Bay

Each May and June, millions of Atlantic horseshoe crabs come ashore along the East Coast to spawn. The height is usually when there is a full moon or new moon, creating the highest tides of the month. 

The result is those familiar helmet-shaped shells of Limulus polyphemus and trillions of their greenish eggs.

At least 11 different species of shorebird rely on horseshoe crab eggs as their primary food source for about 2-3 weeks during their migration. Migrating to their breeding grounds in the Arctic, some come from as far away as the southern tip of South America. Recent declines in the horseshoe crab population have triggered similar and more drastic declines in shorebird populations.

Red knots feeding near horseshoe crab. Photo by Gregory Breese/USFWS

Horseshoe crabs are often called "living fossils" as they are thought to have changed very little in the last 450 million years. Scientists are still not sure if they were land-based arachnids that moved into the sea or an ancestor that stayed put in the oceans. Recent genetic research favors arachnids, placing them alongside spiders and scorpions.

The horseshoe crabs spawn from Maine to the Yucatan Peninsula, but our own Delaware Bay is the center of activity. The warm water and mild surf with sandy shores must be appealing because some of the crabs have come from more than 60 miles out from the continental shelf off the mouth of the bay.

The blue blood of the Atlantic Horseshoe crab is used in medical testing of equipment and vaccinations to detect bacterial contamination in minute quantities, and the crabs have always been harvested as bait. The Atlantic horseshoe crab is currently considered “Near Threatened” by the IUCN. While not currently listed as a threatened species by the State of New Jersey, there is currently a moratorium on the harvest of horseshoe crabs within the state. With this law, it is illegal to remove a horseshoe crab, dead or alive, from its habitat in the wild.



conservewildlifenj.org/species/fieldguide/view/Limulus-polyphemus/

fws.gov...Modeling-a-Future-for-Horseshoe-Crabs-and-Red-Knots

Atlantic Brant Study in NY and NJ

During winter 2018, the NJDEP Division of Fish and Wildlife kicked-off a 5-year collaborative Atlantic brant migration and breeding ecology study with the New York Department of Environmental Conservation and the Canadian Wildlife Service.

Atlantic brant - Photo: Andreas Trepte - Own work, CC BY-SA 2.5

Atlantic brant are a small goose species that breeds in northern Canada and winter in the mid-Atlantic region of the United States. About 90% of the entire population winters along the coast of New Jersey and New York. 

During the next two years, crews will be marking brant with GPS transmitters and tiny geolocators. The geolocators are clear, plastic electronics about the size of a "fat nickel" and are attached to a red and white plastic leg band with a plastic cable lock tie.

This study is using GPS backpack and tarsal geolocators during 2018-19 on both the wintering grounds in New Jersey/New York and breeding grounds in Nunavut, Canada. Marked birds will provide insight into the following Atlantic brant questions:

If you encounter a marked Atlantic brant, check out the information at njfishandwildlife.com on how to help and what to report - especially if you find a bird with tarsal band or backpack transmitter shot or dead.

Horseshoe Crabs and Shorebirds Return to Delaware Bay

USFWS Photo

Late April means that a ritual of "living fossils" moving onto beaches will happen again.

The Wetlands Institute newsletter reminded me that the migration and spawning of horseshoe crabs has been happening for more than 450 million years is here again.

And where is the largest population of spawning horseshoe crabs in the world? Delaware Bay.

They can be found from Maine to the Yucatan Peninsula. Limulus polyphemus, the American Horseshoe Crab, is actually more closely related to spiders, ticks, and scorpions than crabs.

The migration and spawning also brings shorebirds who are migrating from Central and South America to Delaware Bay for a rest stop and critical meal. The shorebirds have a 3,000 – 9,000 mile annual journey to their Arctic breeding grounds.

Humans have a variety of positive and negative interactions with horseshoe crabs.

• Native Americans along the Delaware Bay and River ate their eggs. 
• They were used as fertilizer and hog food in in the 1800s and it was an active industry on Delaware Bay.
• Their white blood cells contain a chemical (LAL) used to test for contaminants in injectable drugs and vaccines and other medical applications.
• They are still used as bait to catch eel and channeled whelk, mostly for overseas markets, but NJ has a moratorium on the harvesting of the crabs due to over-harvesting.
• Development along the Delaware Bay has reduced access for the crabs to spawn, but there are ongoing restoration efforts.

Baby horseshoe crab  - via Wikimedia

The combination of crabs and birds brings many people to the bay to observe. Besides the birds, you might see female crabs with males in tow coming ashore on the incoming tide. Her fertilized sticky, green eggs are placed in the sand in several nests, and the tide will take the crabs back out into the shallows to wait until the next incoming tide and the process will continue. A full moon (May 10) and higher tides are usually the peak times, and a female can lay 80-100,000 eggs during this spawning.

A number of groups participate in the reTURN the Favor project 

which works to rescue stranded horseshoe crabs by freeing crabs 

and working on projects  to help remove debris from beaches.

The Wetlands Institute holds a Spring Shorebird and Horseshoe Crab Festival, 

May 20-21 

with workshops, demonstrations, and field trips that focus on the crabs 

and their role in shorebird migration. 

Mating pair of horseshoe crabs   - via Wikimedia