An Exceptional Incursion of Phalaropes on Cape Cod in Spring 2023

Phalarope flock, Orleans, MA - 2 May 2023

On the last day of April, 2023, an unprecedented incursion of phalaropes (primarily Red) was detected on the eastern shore of Cape Cod. The first indication that something exceptional was occurring was an eBird report by Megan Miller, who reported 1,050 Red Phalaropes at Nauset Light Beach in Eastham during the early afternoon. She counted only the birds close to shore, noting many more birds out beyond the surf line; she estimated two-thirds of the birds were flying south. She then headed south to Nauset Beach in Orleans and recorded an additional 423 Reds in about 45 minutes, some of the birds flying over the beach and even the parking lot.

When Megan’s eBird reports hit email inboxes, I and several other local birders hustled to Nauset Beach to witness the phenomenon. Conditions were poor with fog and drizzle driven by a light southeast breeze, limiting visibility to just a hundred yards or so and making it virtually impossible to see birds much beyond the surf line.

Even though the weather improved the following day and continued mostly clear throughout the week, the birds remained for the next several days, though in steadily diminishing numbers. There were three eBird reports from Nauset Light on 29 April and two from Nauset Beach the same day, and no phalaropes were noted at either site, so it seems clear the birds arrived on the 30th (perhaps overnight).

Although phalaropes were recorded along the entire eastern shore of the Cape, the center of abundance was the Nauset area from Orleans north to southern Eastham, where thousands were present initially. The few reports to the north numbered in the low hundreds. A few birds made it into Cape Cod Bay, the highest count being 73 Reds, 4 Red-neckeds, and 29 unidentified phalaropes at First Encounter Beach in Eastham on 1 May, with just a few found farther west to Sandwich.

A handful of phalaropes were noted from Nantucket Sound beaches on the south side of the Cape as far west as Falmouth. None were reported from Nantucket or Marthas Vineyard, perhaps reflecting a lack of coverage rather than a lack of birds. Phalaropes were also scattered along the mainland coast from Manomet in Massachusetts north to central Maine, mostly just single-digit counts.

The last phalaropes at Nauset were reported on 5 May, but scattered birds (mostly singles) were seen along the mainland coast through 7 May.

Single inland Red Phalaropes were in Bedford, MA (~18 miles from the coast) on 1 May, Rochester, NH (~24 miles inland) on 2 May, and Sanford, ME (~10 miles inland) also on 2 May.

The total number of birds involved can only be conjectured, but certainly was many thousands, and possibly tens of thousands. Counting the birds in the Nauset area was challenging at best, as the surf remained rather high throughout the period combined with some birds being in almost constant motion. At times there seemed to be a persistent northward movement, while at other times a continual southward movement was noted. These movements seem likely to have been the birds relocating to the areas of peak food abundance after being drifted up or down the shoreline by the currents (which change with the state of the tide), rather than migration. The highest number recorded in eBird was of 3,000 Reds on 1 May.

Although Red and Red-necked phalaropes occasionally appear close to shore on Cape Cod (and elsewhere in the Northeast), both in spring and fall – though more often thee latter – their appearance in numbers has invariably been associated with coastal storms, and has been of relatively brief duration, the birds returning to sea quickly when weather conditions improve. The 2023 spring incursion seems to have been unique in that there was no wind strong enough to blow phalaropes (or any other seabirds) inshore and the birds remained, albeit in steadily diminishing numbers, for several days. A more detailed synopsis of the weather is presented below.

So, if weather is unlikely to be responsible for this remarkable phalarope show, what was the cause? Food is the next thing that comes to mind. But if food, was it a shortage of food in the normal offshore haunts of northbound phalaropes in late April?  Or was it an unusual abundance of food along the immediate coast of the outer Cape? The former seems the most likely, though there was no visual evidence that the birds were starving or otherwise stressed. (However, one could argue their mere presence in littoral waters was evidence of stress.)

To my knowledge, only a few dead birds were found and these individuals were not thought to be emaciated. Several incapacitated birds were brought to Wild Care in Orleans, all picked up away from the shore, none of which survived. Although there was some mortality, given the number of birds present, it certainly couldn’t be classified as a mass mortality event. Nonetheless, the presence of thousands of Red Phalaropes foraging in the surf is an extremely anomalous event and suggests the birds were under some stress.

Historical Precedence

The only precedent I’ve been able to find for a similar (i.e., apparently unrelated to weather) incursion was well over a century ago on Nantucket. On May 1, 1892 George Mackay, a well-known market gunner during that period, noted numbers of Red Phalaropes foraging in the surf on the south side of Nantucket (Mackay, 1892)). The weather apparently was unremarkable, Mackay noting only that it had been cooler than normal for the previous week and that there was a “strong south by west” wind blowing that day as well as the previous day or two. The birds were actively foraging in the wave troughs close to shore and Mackay collected 15 of them, 14 Red Phalaropes and one female Red-necked. The Reds were in various plumages, though none was in full breeding plumage – in contrast to the 2023 birds, many of which were in full breeding plumage on May 1. Mackay estimated several hundred birds were present.

Later in the month, Mackay noted that phalaropes were “numerous” around Tuckernuck and Muskeget islands during the period 19-22 May, but attributed their presence to strong easterly winds and rain. He also reported that “a few days later thousands were noted, and some two hundred and fifty captured, from Monomoy to Provincetown,” though, unfortunately, Mackay provides no further details or attribution for this report. During the same time frame (21-23 May), Gerrit Miller and Outram Bangs were in Provincetown and observed large numbers of phalaropes in the harbor (Miller 1892). They estimated that at least 2,000 birds, and possibly twice that number, were present, with a ratio of Reds to Red-neckeds of about 20:1. Local fishermen reported “immense” numbers of “bank birds,” as they called them, within a half mile of shore off Provincetown, many even on the beach. Miller also attributed this large influx to strong easterly winds, rain, and, especially, bouts of thick fog. Whether this weather-related incursion was in any way connected to the earlier one is impossible to know, though given that nearly three weeks had elapsed between the two events, during a period of high migratory activity, it seems rather unlikely.

The May 19-23, 1892 weather-related event seems likely to have been the largest spring “wreck” of phalaropes ever recorded in Massachusetts. Another weather induced influx occurred on 5/10/1969, following a strong SSE blow the previous day, when Wallace Bailey recorded 3,000 Red and 700 Red-necked phalaropes on Monomoy. The same blow produced many thousands of birds (predominantly Reds) in Connecticut and Rhode Island, with as many as 6,000+ estimated at one site in the latter state (attribution?). Other large spring counts of Reds include 1,000 at Monomoy on 4/19/38 (Griscom et al.) and 1,000 in Provincetown on 5/26/49 (Allen).

Comparing the reports of one or two observers from one or two sites historically, as in 1892 and 1969, with the 2023 reports involving scores of observers from dozens of sites along the New England coast is impossible, but clearly the recent event ranks as one of the largest aggregations of Red Phalaropes ever seen in New England (at least), and one of the three largest ever in spring, rivaled only the 1892 and 1969 events. It is almost certainly the largest (at any season) lacking an obvious weather component.

Prey Items

The phalaropes were actively foraging in the surf, but whatever they were finding was very small and impossible to see in the field. However, I was able to get a few photos of birds with some sort of apparent prey item in their bills. Three of the best images (a Red and two Red-neckeds) are below. I have sent these images to a couple of marine biologists but they have not been able to identify the organisms. They seem to be some sort of gelatinous creatures, such as salps or cetnophores, and probably of low nutriional value.

Weather

 The weather preceding the event was unremarkable. During the day on 29 April, weak low pressure was located just off the Delaware coast; by midday on 30 April the low had moved north to a position over western Long Island. On that day the marine buoy on the Nantucket Shoals recorded easterly winds gusting to about 30 mph; the winds veered to southeast and diminished, gusting to about 20 mph, later in the day. The buoy in the Gulf of Maine recorded southeast winds on 29 April, increasing to about 25 mph during the afternoon. At that location on 30 April the winds backed to east and increased to 30 mph gusts.

The following morning (5/1) southeast winds continued gusting in the 30-35 mph range, and had diminished to about half that by afternoon. Winds were light southeasterly (<15mph) on 2 May, into the morning of 3 May, before backing to the northeast and increasing that afternoon, with gusts to 25+mph. Winds at the Gulf of Maine buoy continued out of the north-northeast at 15-25mph on the morning of 4 May, before diminishing and backing to the north-northwest that afternoon. Such weather conditions are quite frequent off New England in the spring, or at any season, and certainly not consequential enough to produce an inshore seabird show.

The moderate northeast winds on 4 May seemed to be associated with a small influx of Red-necked Phalaropes from Cape Cod north to central Maine, as well as several Leach’s Storm-Petrels and some very early Wilson’s Storm-Petrels in Cape Cod Bay.

Surface Weather Map - 29 April 2023 (7:00 a.m.)
Several areas of weak low pressure were scattered over the northeastern U.S., with the closest centered over Delaware. Wind at the Nantucket Shoals buoy (about 60 miles southeast of Nantucket) were E at 20-30mph, while at the Gulf of Maine buoy (about 85 miles east of Portsmouth, NY) were light SE, gusting to ~13mph.
Surface Weather Map - 30 April 2023 (7:00 a.m.)
Weak low pressure moved NNE and was centered over Connecticut. Wind at Nantucket Shoals had veered slightly to ESE and diminished to 15-20+mph. In the Gulf of Maine the wind became more easterly at 15-25mph, gusting to ~35mph.
Surface Weather Map - 1 May 2023 (7:00 a.m.)
Low pressure has continued to drift northward and is now centered over southern Vermont/New Hampshire. Wind at Nantucket Shoals was SE at 20-30+mph, diminishing late in the day. In the Gulf of Maine the wind had veered back to SE and increased t0 20-30mph, with gusts to 40+mph.
Surface Weather Map - 2 May 2023 (7:00 a.m.)
Weakening ow pressure was essentially stationary and remained centered over central New England. Wind over the Nantucket Shoals had veered to S and diminished to 10-15mph. Over the Gulf of Maine the wind was SSE at ~10mph, with gusts to ~15mph.
Surface Weather Map - 3 May 2023 (7:00 a.m.)
Weak low pressure continued almost stationary having drifted a bit westward and was now over New York. At the Nantucket Shoals the wind was S at 5-19nog, becoming nearly calm by late in the day. Over the Gulf of Maine the wind had backed to E and increased to 15-20mph, gusting to ~30mph.
Surface Weather Map - 4 May 2023 (7:00 a.m.)
The original low had dissipated, while the two lows that were located south and east of the region yesterday began to merge and intensify a bit to the east, causing NE winds to increase along the New England coast. At the Nantucket Shoals the wind was NE at15-20mph, increasing to 20-30mph by the afternoon. Over the Gulf of Maine the wind was NE at 15-20mph, increasing slightly by afternoon with gusts to ~25mph

The number, or at least proportion, of Red-necked Phalaropes seemed to increase during the period, though to some extent it may have been that they were easier to pick out among the diminishing concentration of Reds. The highest count of Red-neckeds at Nauset Beach was 190 (with 230 Reds) on 4 May; 140 were reported from Coast Guard Beach in Eastham on 1 May.

Curiously, north of Cape Cod, Red-neckeds were more numerous and widespread, especially during the period 3-5 May. For example, 48 Red-neckeds and only 2 Reds were at Dyer Point in Maine (about 5 miles southeast of Portland) on 3 May, and 38 Reds and no Red-neckeds were just around the corner at Kettle Cove the same day. On 4 May 48 Red-neckeds and 12 Reds were at Sandy Neck in Barnstable, MA, and 51 Red-neckeds and only 4 Reds at Andrews Point in Gloucester, MA. The only inland Red-necked was in Sanford, ME, on 3 May (the day after the Red was found there).

In contrast to many of the Red Phalaropes, all of the Red-necked Phalaropes I saw, or have seen photos of, were in full, or nearly full, alternate plumage.

Red-necked Phalaropes

The followoing birds all appear to be females, many in stunning full alternate plumage.

This spectacle provided a rare opportunity to study the myriad early spring plumages of Red Phalaropes. Given their norhbound passage far to sea at a time of year when very few birders or ornithologists get offshore, it’s likely that few if anyone has much experience with the species’ plumages at this season. Thus, I made an effort (at considerable risk to several thousand dollars worth of camera gear!) to photograph as many individuals as possible, primarily late in the day (when the light was most favorable) on 2 & 3 May.

One feature that distinguishes males from females, apart from the brighter, redder body coloration, is the crown: solid black in females, versus mottled gray in males. However, it may be that in the first week of May some females are still transitioning from basic to alternate plumage and their crowns may be mottled or not fully black, as seems to be the case in some of the birds depicted below. It may also be that some, or many, first year females are more male-like in appearance. Thus, assigning a sex (or age) to many of these birds other than the brightest females may not be possible.

Red Phalarope Plumages

The individual below seems to be anomalous in that it’s in the midst of primary molt: the 9th primaries and secondaries are partially grown. Out of scores of phalaropes I photographed in flight, this is the only one that showed evidence of molting flight feathers (the vast majority were molting body feathers). I presume this to be a first summer bird.

References:

Finch, Davis W. 1969. Northeastern Maritime Region. Audubon Field Notes: Vol. 23, No. 4. 568-572.

Mackay, George H. 1892. The Red Phalarope (Crymophilus Fulicarius) at Nantucket Island Massachusettsa. Auk: Vol. 9, No. 3. 294-298.

Miller, Gerrit S. 1892. Crymophilus Fulicarius in Provincetown Harbor. Auk: Vol. 9, No. 3. 298-299.

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