2016 FIELD SEASON REPORT. L e a r n M o r e... 11

Transcription

1 I n t r o d u c t i o n... 2 T h e P r o j e c t... 3 F l a g g i n g... 4 M o o n b i r d... 7 L e a r n M o r e P h o t o C r e d i t s... 12

2 Introduction The Delaware Shorebird Project, managed by the Division of Fish & Wildlife (DNREC), is pleased to present this report of their 2016 field season. The project was established in Delaware in 1997 to study the shorebirds that migrate through Delaware Bay each spring. At that time there was great concern about declining shorebird numbers, especially Red Knot, and the overharvest of horseshoe crabs. Some of the areas of research that we re focused on include population sizes of shorebirds using the bay, their response to limits on horseshoe crab harvest, duration of visits to the bay, weight gain, and areas used by the shorebirds. The results of our research have led to a better understanding of the ecology of the shorebirds that migrate through Delaware Bay. Management of the important horseshoe crab population has been improved and key habitat has been protected. We ve very excited about the restoration project currently under way in Mispillion Harbor, one of the key sites for shorebirds on the Delaware side of the Bay. We hope you enjoy these highlights of the research our Shorebird Team conducts every spring during shorebird migration. Visit NJ Fish and Wildlife to learn about our sister project, the Delaware Bay Shorebird Project and the shorebird research they do in New Jersey! Audrey DeRose-Wilson Delaware Shorebird Project Manager deshorebirds@gmail.com

3 Migration in the Delaware Bay Every spring, the Delaware Bay is host to an extraordinary phenomenon hundreds of thousands of migrating shorebirds and horseshoe crabs amass on the Bay s shores. The crabs come to spawn and lay millions of tiny green eggs which the shorebirds come to eat. The Delaware Bay is a critical stop over point for migrating shorebirds to rest and refuel, some of whom have already traveled 7,000 miles. They are heading to their Arctic breeding grounds and need to consume enough protein rich crab eggs to almost double their body weight before departing on the last 2,000 mile leg of their journey north! But current shorebird numbers are at low compared to past years, particularly the Red Knot (Calidris canutus rufa), and the yearly phenomena that visits the Delaware Bay could be in danger of disappearing if further population declines occur. The Delaware Shorebird Project began in 1997 in response to the sudden drop in shorebird numbers observed during the early 1990s with the hopes of discovering the cause of the population crash. Now entering its 20 th year of research, the Delaware Shorebird Project continues to identify and protect the resources vital to ensuring the successful migration of shorebirds each year. Following the arrival of the first early migrants in May, the Delaware Shorebird Project s team of volunteer citizen scientists and State, Federal, and international researchers converges on Delaware s bay beaches to begin another season of shorebird research. The Shorebird Team dutifully collects data each year by daily walking beaches counting shorebird flocks, trapping shorebirds to assess health, and looking for marked or flagged individuals. The 2016 season saw 55 volunteers from the UK, the Netherlands, and 11 states contribute over 3,600 hours to shorebird research in the Delaware Bay!

4 Flagging and Resighting An important part of shorebird research is learning the different locations shorebirds visit throughout the year. This is especially important for world class travelers like Red Knots that nest in the Arctic, winter in South America, and migrate through the Delaware Bay. Researchers here and abroad capture and mark birds with coded flags that uniquely identify individuals. Flag codes consist of varying combinations of numbers and letters and are typically 3 characters long though some 2 character flags do occur. The flags, which are placed around a shorebird s leg, are small enough not to interfere with flying but large enough to be read through spotting scopes and some cameras. Anybody can read and report a flagged bird! Remember to record species type, flag color, flag code, and where the bird was seen. Report sightings and submit photographs to bandedbirds.org so that the birds can be tracked across the world. You can also learn where else the bird has visited and when it was first flagged! If observing shorebirds, please keep your distance and do not disturb these distant travelers. They are on a short time schedule and any extra flying reduces their ability to put on much needed weight. While the Delaware Shorebird Project only flags Red Knots, Ruddy Turnstones, and Sanderlings, other projects both here in the United States and abroad flag many other species of shorebirds depending on their projects research goals. The majority of flagged shorebirds seen in Delaware are Red Knots, Ruddy Turnstones, and Sanderlings but other flagged shorebirds including Semipalmated Sandpipers, Short-Billed Dowitchers, and Dunlins do visit occasionally.

5 Flagging and Resighting In addition to carrying unique identifying codes, the color of the flag identifies where the bird was originally flagged. Each color represents a different country or group of countries as indicated on the map to the left. For example, the Red Knot featured at the top of the page wears red flag HMN signifying that it was flagged in Chile. The Semipalmated Sandpiper pictured on the bottom right has a blue flag reading AK8 indicating that it was flagged in Brazil. Orange flag CNP on the Red Knot at the bottom left shows that it is an Argentinian flagged bird. During the 2016 field season, the Delaware Shorebird Team identified over 3,600 uniquely flagged individuals among the hundreds of thousands of shorebirds that visited Delaware. The map on the following page divides up the total number of resighted Red Knots, Ruddy Turnstones, and Sanderlings observed by our Shorebird Team based on flag color. Unsurprisingly, the majority of flagged shorebirds resighted this year were flagged in the US with green flags. Several other countries were also represented including Argentina, Brazil, Canada, the Caribbean, Chile, Mexico, and Surinam.

6 Canada (White) 55 Red Knot 40 Ruddy Turnstone USA (Green) 925 Red Knot 1912 Ruddy Turnstone 460 Sanderling Caribbean (Pink) 2 Red Knot 1 Ruddy Turnstone Surinam (Black) 2 Red Knot 2 Sanderling Mexico (Purple) 1 Ruddy Turnstone Chile (Red) 11 Red Knot Argentina (Orange) 151 Red Knot 1 Ruddy Turnstone Brazil (Blue) 8 Red Knot 44 Ruddy Turnstone 1 Sanderling

7 Moonbird By flagging shorebirds, researchers can learn more about their movements their migration pathways of choice, where they winter, where they nest, and what stopover points they visit. The map to the left highlights the known locations that Red Knots frequent but there are certainly other destinations that remain undocumented. Flagging is also used to estimating stopover population size, individual survival rates, and survival of the species as a whole. No one knows exactly how long Red Knots can live but their average lifespan is between 4 to 7 years. The life of a Red Knot is challenging and migration holds many dangers including predators, severe weather, threats to food supply, and the disappearance of good habitat. But Red Knots are born survivors and there are some who continually beat the odds year after year. Like Moonbird. Moonbird is the nickname given to the oldest known Red Knot. He was at least 2 years old when he was flagged as orange B95 in Tierra del Fuego, Argentina in Today, Moonbird is at least 23 years old and continues to make his long 18,000 mile yearly journey between Argentina and Canada. He has made this trip so often that he has flown over 400,000 miles the equivalent of flying to the moon and almost all the way back! B95 s incredible journey can be seen mapped out on the next page. Moonbird has been seen many times and in many locations since he was first flagged, occasionally disappearing for long stretches of time. He was last seen in northern Canada in 2014.

8 ,so ArcttL IOS- 90 Ocean IC 60. CANADA ,...-,r L.Su i<w - L M1dugan UNITED 7.,/ - f -. -,. - - " STATES,t, C,,.,., KEY B95's stopover sites w O Other important stopover sites for nt{a red knots B95's migratory routes Rufa red knot breeding grounds o P C,: IDS" 90 B95's FLIGHT LEGS Rio Grande, Tierra dcl Fuego, Argentina, to San Antonio Bay, Argentina: 900 miles San Antonio Bay, Argentina, to Lagoa do Peixe, Brazil: 1,000 miles Lagoa do Peixc, Brazil, to Delaware Bay, U.S.: 5,000 miles Delaware Bay, U.S., to ncfa red knot breeding grounds: 2,000 miles Ru/a red knot breeding grounds to Mingan Archipelago, Quebec: 1,500 miles Mingan Archipelago, Quebec, to Maranhao, Brazil: 3,700 miles Maranhao, Brazil, to Rio Grande, Tierra del Fuego, Argentina: 3,700 miles / ARGENTINA PERU r. - - I ' ' -,.'""""... Amot.<>f\R. AMAZON RAI N FOREST BOLIVIA I I -._; I -1 '., - BRAZIL o fgulfofsan]orge,'<,, "' --," _,:> Bahfa Lomas AclaLc Coasl Reserve oftietta del Fuego Rio Grande TIERRA DEL FUEGO 60. \) < I' Arca of detail 0 Mil.es 0 Kilomecers J,000 Scale at Equator 1,

9 Escape and Overweight The Delaware Shorebird Project routinely traps shorebirds in the spring to assess the health of the flock and to flag new individuals. When shorebirds are trapped, each bird is first outfitted with its own unique flag before other data like age, weight, sex, and body measurements used to assess the condition and health of the bird are collected. During the 2016 field season, the Shorebird Team caught over 1,700 shorebirds including Red Knots, Ruddy Turnstones, Sanderlings, Semipalmated Sandpipers, Short-billed Dowitchers, and Dunlins. One particular Ruddy Turnstone that was caught this year has become famous for his swift escape after receiving his flag but before any other data could be collected. The three letter code on his flag? It reads 007! Almost all shorebirds that visit the Delaware Bay during spring migration arrive somewhat emaciated like the Sanderling in the top photo. They can be expected to almost double their body weight within their two week stay. Not only do they need to recover from their several thousand mile journey to Delaware but they also need to gain weight to sustain them on the 2,000 mile journey to the Canadian arctic where food may not be readily available for several weeks. During this time, they must establish territories, mate, prepare a nest, and lay eggs timed perfectly to hatch coinciding with the arrival of a massive insect food supply. But they have to be careful, if they eat too much, they may end up like the Sanderling in the middle picture and be too heavy to fly! Such was the case with one Sanderling that trapped this year. This rotund little bird weighed in at an astonishing 106g, overshooting the desired departure weight of 85g! He gained so much weight that he was unable to fly and instead waddled slowly down the beach before resuming normal shorebird activities.

10 The Weight of a Bird One of the most indicative sign of a healthy shorebird flock is successful weight gain. When Red Knots first arrive in Delaware, they weigh on average 120 grams. During their stay in the Delaware Bay they must feast on enough Horseshoe Crab eggs to bulk up to 180 grams. They need the extra weight to sustain them on the last leg of their journey north and well into the breeding season. Food availability is not guaranteed upon arriving in the Arctic. The graph below depicts the average overall body mass for each of our target species gathered from six trap days. The points on the figure represent the average body mass of birds weighed during a single catch. Overall, the graph shows that average body mass increased for all shorebirds shorebird species trapped during the progression of the 2016 spring shorebird migration. Figure 4. Average weight (in grams) for individuals of each species captured on six cannon net catches in 2016.* The average mass for Red Knot in the final catch comes from a single individual that weighed grams.

11 Want to Learn More? The research that we do, past and present, would not be possible without the continued contribution of our collaborators at the US Fish and Wildlife Service (USFWS), the Delaware Museum of Natural History (DMNH), the British Trust for Ornithology (BTO), and the Wash Waders Ringing Group (WWRG). This project would not perform at such a high caliber without their incredible dedication, commitment, and the expertise that they bring to the project each year. Equally important are our dedicated volunteers. It is because of their hard work, talent, enthusiasm, and commitment to shorebird research that allows us to collect such an extraordinary amount of valuable data every year. Thank you for another successful field season. Anyone interested in volunteering for the 2017 Shorebird Field Season should visit us at Delaware Shorebird Project to learn how. Be sure to also check out the links below to learn more about Red Knots, other shorebird migrants, Horseshoe Crabs, and ways you can help! Delaware Museum of Natural History Conserving Shorebirds in the Atlantic Flyway Just Flip EM (Horseshoe Crabs) Red Knot (Audubon) Birders Can Help! (E-Bird)

12 Photo Credit Title Page: Audrey DeRose-Wilson DNREC (top); Rob Robinson (bottom) Page 2: Rob Robinson (top); Rob Robinson (top middle); Bill Buchanan USFWS (bottom middle); Greg Breese USFWS (bottom) Page 3: Rob Robinson (top); Greg Breese USFWS (top middle); Bracken Brown DNREC (bottom middle); Andre Duiven (bottom) Page 4: Greg Breese USFWS (top); Greg Breese USFWS (top middle); Bill Buchanan USFWS (bottom middle); Rob Robinson (bottom) Page 5: Greg Breese USFWS (top); Pan American Shorebird Program (middle); Greg Breese USFWS (bottom left); Jean Iron (bottom right) Page 7: British Trust for Ornithology (top); USFWS (middle); Jan van de Kam (bottom) Page 8: Macmillan Publishing Page 9: Greg Breese USFWS (top); Rob Robinson (middle); Bracken Brown DNREC (bottom) Page 11: Kevin Kalasz DNREC (top); Greg Breese USFWS (top middle); Kim Cole (middle); Jeff Shenot (bottom middle); Greg Breese USFWS (bottom) Page 12: Ruth Walker (top); Ruth Walker (top middle); Kevin Kalasz DNREC (bottom middle); Bill Buchanan USFWS (bottom) Page 13: Guy Anderson (top); Doug Wechsler (bottom) Recommended citation: Hawk, V., and A. DeRose-Wilson Field Season Report. Division of Fish & Wildlife, Delaware Department of Natural Resources and Environmental Control.

13