Conserve Wildlife Blog

Archive for the ‘Birds’ Category

An Osprey Rescue

Monday, July 17th, 2017

By Meghan Kolk, CWF Wildlife Biologist

I would like to take the time to share a noteworthy event from last week, as well as highlight a CWF volunteer who deserves recognition for his dedication to wildlife.  CWF received a call last Friday from a concerned citizen about an osprey chick that had fallen from its nest in Avalon.  Osprey chicks are extremely vulnerable to summer storms, and are often blown right from their nests in strong winds.  The storm that pushed through the area Thursday night had likely blown this chick out of its nest onto the marsh below.  This particular nest had just been surveyed on July 6 and had contained three young chicks.

osprey chick down on marsh after severe storms

Often when staff members are not available to respond to calls like this, we rely on our volunteers to represent us.  In this case, when CWF volunteer John King got the call, he hooked up his boat and immediately headed out to assess the situation in hopes of making a rescue.  When he arrived on the scene, John realized that there were actually three osprey chicks on the ground below the nest; however, two of them were unfortunately already deceased.  The parents were also sitting on the ground with the one surviving chick when he arrived.  John picked up the chick and examined it for injuries.  When he determined it was in good condition, he carried it up a ladder and placed it back into the nest as the parents circled and screamed above him.  As he left the site, the parents immediately returned to the nest to check on their chick.

Osprey chick returned to the safety of it’s nest

Even though John was only able to save one of the three chicks, this was still a success story that would not have been possible without the help of a devoted volunteer.  The concerned citizens who had called in the emergency watched the whole rescue from across the lagoon and reported back the following day that the chick was sitting up in the nest looking healthy.  CWF also greatly appreciates citizens who care enough to observe wildlife responsibly and report wildlife emergencies when necessary.

Adult returns to nesting platform after chick is safely returned to nest.

John King has been volunteering for CWF for many years and has worked on several projects including the Calling Amphibian Project, NJ Tiger Salamander project and the NJ eagle project.  He has been very involved with the NJ osprey project, headed by CWF’s Ben Wurst, assisting with osprey surveys during the breeding season and helping to construct and erect nest platforms over the winter.  In addition to CWF, John also volunteers with many other conservation organizations and is always happy to lend a hand.  Although he is retired, his volunteer work is practically a full time job. I sincerely admire John’s continued enthusiasm and his dedication to wildlife, and I believe the world would be a better place if there were more people like him.

Conserve Wildlife Foundation of NJ thanks you, John!

 

Fallen Eagle Nest, Leads To Eagle Rescue

Saturday, June 10th, 2017

and one lucky eagle chick.

Larissa Smith, CWF Biologist

Friday afternoon before Memorial Day weekend I received a call from one of the Eagle Project volunteers, Heiki Poolake. A nest which him and his wife Donna monitor, had fallen out of the tree and the chick was on the ground. The chick was approximately 9 weeks old so still several weeks away from fledging (leaving the nest). On the ground the chick was susceptible to predators. While the adults were in the area and keeping an eye on the chick they most likely weren’t feeding the chick on the ground.  One option would be to build some type of “nest” back up in the nest tree. That option would require a climber and their weren’t any available. The next option was to install an osprey platform at the site and place the chick in the platform. We have done this successfully in the past when an eagle nest had fallen.

Eagle chick on ground 5/26/17@ D. Poolake

ENSP Principal biologist Kathy Clark, CWF volunteer Matt Tribulski , the Poolakes and myself all met out at the site.  The platform was installed close to the original nest tree with extended perches to allow the chick to “branch”.  It was determined that the chick was in good health, no broken bones or other issues from the fall. The chick was banded with a silver federal band and a green NJ Band E/50. Measurements were taken which helped to determine that the chick was a female and almost 9 weeks of age. She was fed some fish since we were unsure when she was last fed and placed in the nest platform along with more fish.

The Poolakes went out the next day and found her once again down on the ground and placed her back in the nest.  The fish we had left were gone which was a good sign she was eating. She remained in the nest until  June 8th when she was perched on the branch of a near by tree.  Both adults were also perched close by, keeping an eye on her.  At this point she was approximately 11 weeks old around the time when chicks her age start to branch and practice flying. She’ll stay in the area for the next few weeks with the adults as she learns to hunt on her own and strengthen her wings.  The first year is tough for eagles as they learn to survive on their own. We wish E/50 luck and hope to see her nesting in NJ someday.

Shorebirds lift off to an uncertain end from Delaware Bay

Thursday, June 8th, 2017

By Dr. Larry Niles, LJ Niles Associates, LLC

Red knot by James Fiorentino.

I am reviewing a new paper by Sjoerd Duijns, a student working on the benefits of being a fat shorebird. Still, a draft, the paper analyses data from radio-tagged red knots leaving the Bay in good condition (i.e. fat) and finds they may leave later from Delaware Bay than lighter birds but arrive earlier in the breeding grounds because they can pick the best time to leave. They are also more likely to breed successfully and survive the Arctic breeding season to the following fall. In other words, being a fat knot on Delaware Bay makes life good.

So, in light of this new information, how did the red knots and other shorebirds fare in this year’s Delaware Bay Stopover?  One must not be firm, with so many unknowns, but here’s a working biologist’s best guess.

By all accounts it was one of the worst years in recent memory, but with a twist that offers a glimmer of hope.

First, the Bay’s water reflected an unusually cool May and never really warmed to the levels necessary for a really good horseshoe crab spawn until the very end. This caused odd occurrences of crab spawning. For example, crabs bred in greater densities at the southern beaches this year, more than in previous years. The spawn at Norburys Landing, just south of the commercial oyster aquaculture development zone (ADZ), was one of the best this year, and knots and other shorebirds used the area in great number. One can only guess the water temperatures warmed over the wide inter-tidal flats provided just enough to elicit spawning. The same process was true of all the creeks on the Bay.

Laughing Gulls and shorebirds feast on horseshoe crab eggs at Norbury’s Landing just south of the Aquaculture Development Zone. (below)The southern portion of the bay was much more important this year because waters warmed faster on the large inter tidal shelf of this portion of the bay.

Second, the knot numbers never really climbed to the levels of the last three years. I’m guessing this was illusory, a consequence of the count being done on two days at the peak. It’s likely many more birds came to the Bay and seeing many birds for too few eggs, left for better resources elsewhere. Those that left were probably short distance winterers – those from relatively close in Florida and other nearby areas. The Bay’s horseshoe crab eggs would help them too, but they can get by on Atlantic Coast clams and mussels. The long-distance birds are the ones that need the Bay’s resources.

Third, when finally, the spawn got underway, a freak concurrence of wind and tide killed many thousands of crabs, potentially damaging the population and very likely ending any possibility of a really great spawn. The cobblestone road of crabs on the water’s edge. We saw none of that this year. Not once.

 

 

The upper graph compares predicted high tides ( in blue) with the actual high tide (in Red). On the night of 26 May. This occurred during the lunar spring tide, the highest in May. Finally, a brief burst of NW wind pushed the abnormally high tide into waves breaking across the beach berm, carrying with it tens of thousands of horseshoe crabs.

In a freak concurrence of wind and tide, waves pushed horseshoe crab over the beach into the marsh by the thousands.

Grim results, but here’s the twist. In good years, knots leave near the 27th of May. One day they jam the beach gobbling up eggs, the next day there gone. In bad years, they linger. In 2003, we caught birds on the June 10th.  There’s a cost to this of course, in lower survival and failing production. This year was a new in between. By the time of departure on May 27th, less than a quarter of the knots were prepared to leave. But they hung on until the 30th, blessed with a new flush of horseshoe crab eggs created by a middling spawn and a northwesterly wind churning up the beaches and exposing deeply buried eggs. Did the birds gain enough weight?

It’s hard to say, our last catch of just 33 knots suggests they might have, but an end-of-the-season catch makes a poor assessment. Once birds start leaving, the ones behind could be the light birds not ready to leave, or the heavy birds waiting for better weather. We won’t really know until the fall counts in the southbound stopover or the winter count in Tierra del Fuego.

This, our 21st season of intense research and conservation on Delaware Bay by all accounts will be like no other. Throughout all of it, the team of scientists and volunteers remained inspired, energetic and resourceful. In this one month, we conducted more scientific investigation and conservation than most projects do in an entire year. Whatever the outcome of this year’s stopover season, our team can look hopefully to the north and know that all that could be done for the birds was done.

Those of us that were paid for our time sincerely thank those who volunteered their time including; the stewards that manned the closed beaches helping hundreds of people understand why closures were needed; the volunteers in the banding team who endured long hours of preparing equipment, making bands, sewing nets and keeping cages and of course counting, catching and processing birds; the volunteers who doggedly pursue opportunities to resight flagged birds to estimate numbers and yearly survival; the volunteers that provided meals every single night, a welcome relief from a hard day’s work; and finally, the volunteers that went out all over the Bay to save horseshoe crabs in weather both good and bad. We all did our best. God help the birds and horseshoe crabs.

Our banding team on a catch at South Reeds.

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


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Scarcity and Abundant – Shorebirds Near the Finish Line on the Delaware Bay

Wednesday, May 31st, 2017

By Dr. Larry Niles, LJ Niles Associates, LLC

Our latest catch of red knots and ruddy turnstones two days ago (May 27) suggests 2017 to be one of the most challenging years for our 20 years of work on Delaware Bay. It challenged the birds for certain.

For example, as of two days ago (May 27), the average weights of red knots remain mired in the mid 160’s when it should be in the 180-gram range. This seems a minor difference but to red knots it means a flight through the cold and often inhospitable north country of Canada and dropping out of the sky never to be seen again or landing and never attempting to breed. We really don’t know for sure what happens to ill-prepared shorebirds, except they are less likely to be seen ever again. In 2017 most birds will be ill prepared.

This histogram of the red knot catch made on May 27, 2017 shows the range of weights and the number of birds in each weight category. The average of 168 is far lower than the 180-gram threshold necessary for a successful flight to the Arctic.

This season also challenged our understanding because it lies so far outside the norm. To be sure the cause of this dramatic scarcity of horseshoe crab eggs springs from the cold weather this May. We started with a good crab spawn in the first week of May, when water temperatures rose somewhat faster than normal, a consequence no doubt of one of the warmest winters on record. Then cold and wet weather dogged the Bayshore until the day of this post. Today, temperatures will rise no higher than 70 degrees Fahrenheit and the prospects for warmer weather are unlikely for the rest of the week. The cold air temperatures forced down the bay temperature in the second week and although it has gradually improved it is still low by normal standards.

The Delaware Bay water temperature as measured by the bour off Lewis Delaware. The Bay warmed early until the second week of May when cold weather chilled the Bay.

All of this led to generally diminished horseshoe crab eggs especially on the beaches, the mainstay of most stopovers of the past. This year crabs mostly spawned in the creek mouth and outer creeks shoals, mostly spurred to spawn by tidal waters warmed by the movement in and out of the small estuarine systems. Water moves in with the tide and out again to the creek mouths twice a day warming the shoals.

The Importance of Tidal Creek Mouths and Shoals

A shoal at the mouth of BayCove creek and the crab spawn on Reed creek.

The creeks also accumulate sand leaving them loose and perfect for crab spawning. Even in good years, egg densities in the creeks top all beaches, no matter where they occur. The sands of the shoals loosen by the waves of the Bay and release more buried eggs than those buried in the beaches, making more available to the birds. The creek mouths on the Cape May peninsula from Green Creek to Moores Creek saved the birds from an even worse fate this year and the best were those that benefited from the restoration of Reeds, Cooks, Kimbles and Pierce Point Beaches. As it happens a major portion of the Bay’s knots stayed in this area throughout the entire month but flying widely in search of pockets of good spawning in other places. This year Norbury’s in the south and Goshen in the north stood out, and extended the core stopover area.

Horseshoe crabs breeding at Reeds South shoal.

Spawning Starts Again

Then in the last three days all changed. The new moon tides, reaching around 8 feet for four nights in a row, spurred spawning despite the relatively cool water. Today, May 29, the crabs shifted into high gear.

It takes a lot of crabs breeding to bring eggs to the surface on the beaches, there must be enough breeding for one crab to dig up the eggs of another. For the first time, this occurred in the last few night and we finally saw green eggs on the sand. A welcoming sight for the birds, who could barely stand still and gobble up the fat producing eggs. With most of these Arctic nesting shorebirds remaining in the Bay and apparently feeding right into the night, they still might reach the fat gain finish line and only lose a few days reaching the Arctic. The next few days will tell.

Horseshoe crab eggs litter the surface of North Reeds Beach.

A close up of the same beach. The immense number of eggs on the surface of the beach is in part due to the number of crabs spawning and the wave action of the Bay.

Shorebirds and Gulls feeding near dark in the intertidal flats and creek shoals of Reeds, Cooks, Kimbles and Pierce Point Beaches.

Can they though? A good question and just one of the many that have challenged our team’s knowledge of this well-known stopover. With literally centuries of combined experience (many of our team, including this author, are long in the tooth as the Brits would say) we still kept guessing what would happen next throughout the season. Would the birds suffer mighty declines as a consequence of the generally diminished spawn of horseshoe crabs?  Or will they build weight in time to get to the Arctic in good condition? This is usually the central question.

Why Are There Fewer Knots?

An equally intriguing question, however, is why have red knot numbers in Delaware Bay declined this year? We estimate shorebird numbers in two ways, direct observation by aerial and ground counts and a statistically derived estimate based on the resighting of birds flagged with unique IDs. Our aerial and ground counts tell us how one year compares to another because we have been doing shorebirds counts by airplane, boat and on the ground since 1981. This year the number fell dramatically.

Guy Morrison, Christian Friis and Joe Smith survey shorebirds by airplane near Egg Island Point.

At the start of our project on Delaware Bay in 1986, we had nearly 100,000 knots on the Bay and nearly 1.5 million shorebirds of all species. The number of knots declined to around 15,000 in the mid-2000’s, then jumped to over 24,000 over the last four years. This year our best estimate is around 17,969, a 5,000-bird decline. Why did this happen?

One must always consider the possibility of a large group of birds dying. But this is not likely.

More likely, some portion of the knot flock came to the Bay, and on finding too few eggs or too much competition, moved on to better places. The ones moving on could have been the short distance migrants, those who spent their winter in Southeast US or the Caribbean. These birds travel a shorter distance and so have a longer time and lower energy needs than those that winter in South America. These long-distance migrants would have a very difficult time gaining weight on anything other than crab eggs (I explained this in a previous post). There are two reasons to believe the short distance birds moved on from the Bay this year.

The first is the discovery of birds banded in Delaware Bay this year and reported elsewhere. I reported on Mark Faherty’s Ebird report of a knot he saw in Cape Cod, that was flagged by the Delaware Bay Shorebird Team on May 16, 2017. The second line of evidence is the 1,300 birds seen by our team feeding on a 10-mile stretch of the Atlantic Coast marsh from Cape May to Stone Harbor. Play this out over the entire coast of New Jersey and other places with sand and marsh, like Cape Cod, and one could easily imagine 5,000 knots using other places.

About 200 knots feeding and roosting on the inter-tidal shoal of Hereford Inlet on the Atlantic coast.

But this reduction in population also suggests an explanation for the sudden rise in numbers found in 2013. Did the restoration of habitat on the Delaware Bay coast bring back knots that once used the Bay but stopped because of the lack of available eggs? In other words, did the increase in numbers seen in the Bay reflect a return of birds and not a population increase? This year’s loss may simply be a result of those returning birds, leaving once again.

Let’s hope so. At any rate, eggs are now available to all birds in the Bay and we should start seeing them leave for the Arctic. Let’s hope for that too.

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


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Photo From The Field

Thursday, May 25th, 2017

Shorebirds, eagles, horseshoe crabs and more….

May is a great time to visit the Delaware Bay beaches. The horseshoe crabs are spawning and shorebirds are feeding on the eggs. Please respect the beach closures, so that the shorebirds can feed undisturbed.

Fortescue beach 5/16/17@Bob Bocci

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