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13,000 Red Knots on New Jersey’s Delaware Bay

Thursday, May 21st, 2015
An Update on the 2015 Delaware Bay Shorebird Project

By: Dr. Larry Niles, LJ Niles Associates LLC

We had about 13,000 knots on the New Jersey side of the Delaware Bay (an additional reported 2,000 on the Delaware side of the Bay). Yesterday, we suffered strong NW winds in excess of 20 kts and the birds virtually disappeared. Our daily survey turned up about 6,000 knots, the rest we suspect, finding refuge in Egg Island and Goshen Marshes or with a flyover to Delaware.

 

We will know where they went today. The team will comb the Bayshore for shorebirds with a coordinated ground, boat and aerial survey. The birds gain weight in good time and we expect the first Arctic lift-offs by the 26th. At the current rate, most of the Bay’s population will be off to the Arctic by the 30th.

 

Above is a clip from a new video about knots and our work by Mitch Smith, a longtime supporter of the team and head of the Mitch Smith Media.

 

Learn more:

Dr. Larry Niles has led efforts to protect red knots and horseshoe crabs for over 30 years.

 

2015 Horseshoe Crab Spawn and Shorebird Migration on Delaware Bay

Wednesday, May 20th, 2015
An Update on This Season’s Horseshoe Crab Spawn and Shorebird Migration, Ten Days In

By: Dr. Larry Niles, LJ Niles Associates LLC

Thousands of shorebirds now fill Delaware Bay’s beaches and marshes in a determined effort to regain lost reserves with free-for-the-taking fatty eggs of the horseshoe crab. The crab spawn began ten days ago and has gained momentum over the last week as the volume of eggs grows like a well-funded savings account. The eggs surface as each new female crab digs up egg clusters laid by other crabs or as wind-driven waves pound the always-fluid sandy beaches. At least 8,000 red knots slowly get fat on the eggs scattered on New Jersey’s Delaware Bay beaches.

Eggs on Beach

Eggs on Beach

Both crabs and birds are the beneficiaries of the increasing number of beaches that are highly suitable for egg-laying. In October, 2012, Hurricane Sandy ravaged two-thirds of New Jersey’s best crab-spawning beaches, its strong westerly winds lifting sand and spreading it far from the sea’s edge. Left behind was a jagged sod bank, completely unsuitable for horseshoe crab breeding. The mucky sod starves eggs of oxygen or gasses them with hydrogen sulfide, the by-product of decaying mud.

 

The American Littoral Society, Conserve Wildlife Foundation of New Jersey, the U.S. Fish and Wildlife Service and the National Fish and Wildlife Foundation came to the rescue, restoring many of these beaches to a condition superior to that before Sandy. The restoration team even repaired damages that predated Sandy — beaches with tons of rubble that entrapped crabs in nasty concrete, killing them by the thousands. Now beaches like Thompson’s Beach and Fortescue Beach join the growing number of delicate sandy strands that provide excellent spawning habitat.

Thompsons Beach Before and After

Thompson’s Beach Before and After Restoration

This week, eggs can be found in many places on the New Jersey side of Delaware Bay, and the birds have the freedom to move to those that best suit them. Earlier this month, strong northwest winds drove red knots from the Reeds Beach area to other, more northerly, beaches that saw good crab spawning — beaches that also provide shelter from the winds. Now that the wind and sea have calmed, the birds have returned to the Reeds Beach area, less than 20 miles away, and have resumed gorging on the plentiful eggs that built up in their absence.

Early Morning Shorebirds on Delaware Bay

Early Morning Shorebirds on Delaware Bay

If one were to look for any cloud on the Delaware Bay shorebird horizon, it would lie in the lack of any evidence of horseshoe crab recovery. The current, reduced, population of crabs spawned eggs in great numbers early this May because of a spike in the water temperature, a consequence of unusually warm weather.  So far the promise of this early spawn is holding, and crabs continue to spawn in good numbers. But will it hold until the end of May?

Crabs in Slew

Crabs in Slew

If not, the readers of this blog will witness the outcome. The graph below, developed by long-time team-member Dick Veitch tells the story of a past egg failure. In the early 2000’s, although the population of shorebirds had not yet declined to its current number, the crab population had already fallen to its current number, crushed by the onslaught of a poorly regulated fishing industry.  In those years, all the horseshoe crabs that could spawn had finished by the third week of May and egg densities on the bay plummeted. The birds crammed into the few beaches with eggs like Mispillion Harbor, Delaware, so densely that the beach reeked of off-gassing urinary ammonia.

 

But the number of eggs there was not sufficient to feed the still-large shorebird populations and birds failed to reach a weight – about 180g for red knots — suitable for their journey to the Arctic and subsequent breeding. Where once 80% reached the “good” weight, only 5% did in 2003 (see the second graph).

Percentage of Red Knots Reaching 180 Grams

Percentage of Red Knots Reaching 180 Grams

The percentage has improved thankfully, but only because the number of shorebirds have fallen over the last 10 years, bringing a balance of sorts. Hopefully, with the new beaches, the new protection afforded by the red knot listing and the growing number of volunteers taking part in conservation of the crab and birds, this kind of disaster is behind us.

We shall see.

 

Learn more:

Dr. Larry Niles has led efforts to protect red knots and horseshoe crabs for over 30 years.

Photo from the Field: Timber Rattlesnake Emergence

Monday, May 18th, 2015
Warming weather brings out one of New Jersey’s most misunderstood species

By: Michael Davenport, GIS Program Manager

I recently had the opportunity to accompany Kris Schantz, a biologist with the NJ Endangered and Nongame Species Program, to search for timber rattlesnakes (and northern copperheads) emerging from their dens in northern New Jersey.

Many New Jersey residents are surprised to learn that we have venomous snakes within our state, the most densely populated state in the U.S. We have two venomous species, in fact.

A timber rattlesnake resting outside its den. © Mike Davenport

A timber rattlesnake resting outside its den. © Mike Davenport

The timber rattlesnake is an Endangered species in New Jersey, while the northern copperhead has a status of Special Concern. To learn more about venomous snakes in New Jersey, please read my blog entry from May 13, 2011 and visit our online field guide:

 

2015 Delaware Bay Shorebird Project Continues!

Sunday, May 17th, 2015
Another Season of the Delaware Bay Shorebird Project Underway

By: Dr. Larry Niles, LJ Niles Associates LLC

The value of a shorebird stopover like Delaware Bay can be seen in the shaky cam movie by this author.  Red knots – some recently arrived after a grueling 6,000-mile flight over 6 days of continuous flying – arrive on the Bayshore desperate for food. Over the last 10,000 years, the species has evolved to fly directly to the Bay to feed on the eggs of the horseshoe crab.

The 450-million year-old crab – which is actually in the spider family – crawls ashore and lays pin-sized eggs about 6 inches deep in the sand. When there are many crabs, as here on Delaware Bay, one crab often unearths the eggs of another. Thus they leave millions of fatty eggs on the surface, offering an energy-rich, soft feast for the starving birds. In turn, we get to watch the birds racing for an egg ‘hot spot’!

The birds often arrive beyond depleted. A normal weight for a knot is 130 grams.  Many arrive on Delaware Bay below 100 grams, the equivalent of a human in the throes of profound starvation. But when the birds fly north from the coast of northern Brazil, there’s no turning back. Once they go, they must go all the way.

Map of geolocator track of a South American wintering  red knot

Map of geolocator track of a South American wintering red knot

This year, migrating shorebirds faced a freak tropical storm that could have forced them out to sea, far off-course.  In severe cases, some birds with no remaining fat reserves even metabolize their own muscles, like airplanes throwing out vital equipment to stay aloft. Storms can also prevent birds from lifting off on migratory flights. They are capable of detecting atmospheric pressure changes and can just stay put until a storm passes. We think this is what happened this week when a storm, followed by a strong cold front and consequent northwest winds, prevented a movement north.

The sum of these challenges was lower than normal shorebird numbers during the first week of the stopover. The Heislerville impoundments support a good number of short-billed dowitchers and dunlin, but these species usually arrive earlier than the others and probably came in ahead of the adverse winds. Yet there are very few ruddy turnstones, sanderlings and semipalmated sandpipers on the Bay.

Short bill dowitcher (c) Jan van der Kam  from Life on Delaware Bay

Short bill dowitcher (c) Jan van der Kam from Life on Delaware Bay

The one exception on the Bay is the red knot. At first, we thought that only about 1,000 red knots had arrived in and around Reed’s Beach. Then Jerry Binsfeld and Peter Fullagar, Canadian and Aussie members of our team, found an amazing 7,000 knots at Gandys Beach on the northern Bayshore in New Jersey. Very likely, these are short-distance migrants, coming in from wintering areas in Florida, Georgia and the Caribbean.

Red Knots on Fortescue

Red Knots on Fortescue

Our catch results support this working hypothesis. The knots we caught at Fortescue were at higher weights than normal for this early part of the season, which would be expected if fewer very thin long-distance migrants were part of the average.

The graph shows the weight relative to previous years.

The graph shows the weight relative to previous years.

The histogram shows the distribution of all the birds weights in the catch.

The histogram shows the distribution of all the birds weights in the catch.

Learn more:
Dr. Larry Niles has led efforts to protect red knots and horseshoe crabs for over 30 years.

The Return of Bald Eagles in New Jersey

Thursday, May 14th, 2015
Conserve Wildlife Foundation Releases New Story Map: “The Return of Bald Eagles in New Jersey”

By: Brian Henderson, GIS Specialist

Bald Eagle Story Map

Today, Conserve Wildlife Foundation of New Jersey (CWF) announced the release of “The Return of Bald Eagles in New Jersey” a Story Map that provides a new way to visualize the increasing number of bald eagle pairs nesting in New Jersey over time.

 

For years, CWF has worked closely with the New Jersey Endangered & Nongame Species Program (ENSP) to track and restore the bald eagle population within the state. It has been a rewarding experience for all involved to witness the return of bald eagles to the garden state, and now the public can appreciate the scope of their return as well.

 

The recovery of bald eagles nationally and in New Jersey is fairly well known, but some may not realize that as recently as the mid-80’s there was only a single pair of nesting bald eagles in all of New Jersey. The ban of DDT, combined with restoration efforts by ENSP biologists, resulted in population increases to 23 pairs in 2000, 48 pairs by 2005 and 82 pairs in 2010.

 

In 2014, there were a record 146 active bald eagle pairs nesting in New Jersey. This year, 190 nesting territories are being monitored and currently 88 chicks have been reported at 52 nests; it is still early in the season so we don’t have a count for all nests yet.

 

“The Return of Bald Eagles in New Jersey” Story Map displays the locations of all the known active bald eagle nests in New Jersey from 1985-2014. Users can choose to view the nests active in a single year or over a longer period of time. By choosing a one year interval and beginning in 1985, it’s possible to watch as nests multiply from a single nest in Bear Swamp to densely populating the Delaware Bay coast and spreading across the southern portion of the state and eventually into almost every county of New Jersey. In 2014, the only counties in New Jersey without an active bald eagle nest were Essex and Hudson.

 

The Story Map also highlights “featured” nests, or nests of special significance, including the Duke Farms nest which has been featured on a webcam since 2005 and the Millville nest where a juvenile eagle was fitted with a GPS tracking device in 2014. These featured nests include more information, pictures and links to pages that explore related projects in greater depth.

 

As the bald eagle population has reached record numbers in New Jersey, the raptors have expanded into non-traditional parts of the state, providing more and more people with a chance to glimpse this iconic species. This map highlights the ongoing success of conservation efforts and illustrates that whether you realize it or not, you’re never very far from a bald eagle nest in New Jersey!

 

Learn more:

Brian Henderson is the GIS Specialist for Conserve Wildlife Foundation of New Jersey.