This is a preview of an article scheduled to appear in the September 2004 issue of “Bird Observer.”
North Pool is one of three fresh water impoundments on Plum Island that are managed by the Parker River NWR. The northern end of the pool can be seen from the North Pool Overlook, a small parking area located on the North Pool dike just south of the maintenance buildings. The southern end can be seen from the central dike (separating North Pool from Bill Forward Pool) at the Hellcat nature area and from the south end of the North Pool dike. The marsh loop boardwalk, part of the Hellcat trail system, provides access to some of the North Pool marsh. North Field, containing the granite pillar marking the boundary between Newbury and Rowley, is an extensive grassland area bordering the eastern edge of North Pool, and is part of the habitat, which also includes much of Hellcat forest, that was created and is now protected by the North Pool dike.
Due to a confluence of forces that occurred during the spring and summer of 2004, forces I don’t pretend to understand, the North Pool and North Field areas played host to a wide array of rare and more usual marsh related birds throughout the period. Certainly the presence of a large amount of fresh water in the North Pool by April, and the effects of a cold, long winter, followed by a cool and wet spring, contributed to a burst in bird activity in and around the pool. In addition, the refuge staff has not drawn down the water levels in North Pool, so the pool has held high water levels throughout the period.
As a result, this has been the best spring and early summer in recent memory for a number marsh birds that have been infrequently recorded from the area over the past couple decades. However, this spring is not unusual when considered with a more historical perspective. It simply shows how rich and fecund the fresh water North Pool system can be. None of these species is particularly noteworthy in and of themselves, as all of them have a long history in the Plum Islands impoundments, but this year they are all here at the same time, in reasonable numbers, and many excited birders have gotten their best views, and some life views, of these species. Combine this with the uncertain future that is in store for the North Pool itself, and we have the makings for an interesting story.
Five of these marsh related species are Massachusetts endangered, threatened, and special concern birds. Three of the species, Least Bittern, King Rail, and Common Moorhen, have not been reported from the area in a number of years. In addition to these five species, other species that have been scarce in recent years have had a strong presence in North Pool and the adjacent Bill Forward Pool. These species include Blue-winged Teal, Green Heron, Black-crowned Night Heron, and Sora.
Here is a brief summary of the sightings of a number of these species, plus notes on other marsh birds strongly influenced by the current state of North Pool. These sightings are all from amateur birders (many from the author). The refuge staff does not regularly or even infrequently census this system for its animal inhabitants. If it were not for the diligence of interested naturalists, the status of many of the birds and other animals in this system would essentially be unknown.
This article was written during the first week of July, 2004, a period when most of the marsh birds described herein are silent, and where present, employed with the duties of tending eggs and young. A short note a few months hence may be warranted to describe any evidence of breeding. Please excuse the personal flavor that pops up from time to time.
Flash note: as of July 7th,
King Rails have been seen carrying food in Bill Forward Pool, and a brood of
four downy Blue-winged Teals have been sighted with their mother in North Pool.
Least Bitterns continue to be sighted in North Pool.
Flash note: as of July 14th, juvenile Soras and Virginia Rails have been spotted in North Pool, and a pair of Least Bitterns has been seen flying to and from a specific location in the North Pool reeds.
The species accounts that follow, such as they are, follow a more temporal order than a taxonomic one.
Sora, Recommended for Massachusetts Special Concern Status
My first indication that this might be a special year for marsh birds at North Pool came on April 24th, when I heard a Sora call from the pool while I was walking through the Goodno woods. Years ago I would often hear Soras during spring from the North Pool, but it had been years since I had heard the distinctive “so-RA” and whinnying calls of a Sora there. For the next four weeks Soras were heard calling from the North Pool by many observers, with reports of up to three calling simultaneously. After May 19th reports of calling Soras dropped off, but a few isolated reports continued through June. It is likely that a few pairs of Soras are breeding in the reeds of North Pool this season. The Sora is a rail whose numbers have precipitously declined in Essex County and Massachusetts in general over the past couple decades, and therefore has been recommended for addition to the list of Massachusetts special concern species.
King Rail, Massachusetts Threatened Status
The next indication that something special was happening came on May 27th. On that day large rails began calling from both sides of the central Hellcat dike, and some allowed occasional glimpses. The next couple days were interesting because the rail seen most often, a female who became known as the “mystery rail,” could not be safely identified as either a King or a Clapper Rail. Some of our most experienced field observers weighed in on the question of her identity, but there was no clear consensus. As the next few days passed, however, it became clear through a number of hearings and sightings that there were multiple other rails in the area, and that most if not all were King Rails. May 31st was the peak sighting day with one report of eight rails nearly simultaneously in sight from the central dike.
With the mystery rail calling loudly through the first few days it seemed only a matter of time before one of the male King Rails from the other side of the dike would join her. On June 4, things quieted down considerably, and many visitors were treated to frequent views of a pair of rails, a large male King, and the smaller female mystery bird. They chased and followed one another, swam, bathed, flew, fed, copulated, skulked, preened and allo-preened, shared minnows, and just plain loafed, all in plain sight, time after time. These “showings” continued until around June 8th or so when sightings began to drop off. However, the male King Rails was seen many more times, while the female was less in evidence after this date, a strong indication that copulation had the intended effect. Also during this period a pair of pure King Rails were occasionally seen and heard from North Pool on the other side of the Hellcat dike. There probably are at least two breeding pairs of King Rails in the Hellcat pools this summer, and with the earlier reports of up to eight birds we can hope that another pair or two has settled further north in North Pool. Many birders got their life views of King Rails from Hellcat this year, and many of us have had a crash course in the confusing plumage characteristics of the King and Clapper Rails.
For whatever the reason of the phenomenon, the presence of numerous King Rails in the two Hellcat impoundments is a major story this year. As a side note to the King Rail story, a pair of Clapper Rails has been heard from the “usual location” south of lot one along the Plum Island River.
Least Bittern, Massachusetts Endangered Species
Then came May 30th. On that day I arrived at Hellcat around 5:00 a.m., to the strident “kit kit krrrr” calls of the mystery rail. But I could also hear “poo poo poo” calls of Least Bitterns coming from North Pool in the reeds opposite the former blind. From that location there is a cut visible through the reeds that heads toward the concrete water control structure on the North Pool dike. There were two Least Bitterns, one calling from each side of that cut, and a probable third, further south. For the next couple days these two or three Least Bitterns continued to call from this area. A few observers managed quick views of these birds when they flew across the cut. After a few days one of the birds moved much closer to the Hellcat dike, and has been glimpsed occasionally from the central dike and the marsh loop. This bird called incessantly for many days, while the bird nearer the former blind called only occasionally. After June 14 calling dropped off, though birds are still being occasionally seen at the edges of the reeds or making short flights. As for the Soras and rails, hopes are high for breeding birds in the reeds.
After all the records were checked, we discovered that a Least Bittern was heard in the North Pool marsh as early as May 16th and again on May 28th. May 30th was the day that the birds became obvious by calling in earnest. As another note to the Least Bittern sightings, there is a pair of Least Bitterns residing in the reeds of the east-central part of Stage Island Pool this summer, where again, breeding is quite likely.
Common Moorhen, Massachusetts Threatened Species
Least Bitterns weren’t the only new marsh birds in evidence on May 30th. As I was walking the Marsh Loop, looking the spot closest to the calling Least Bitterns, I heard a call from the North Pool in the direction of the concrete control structure, a call I could not identify. Because the King Rails were then in their calling heyday, I passed it off as an unusual call, possibly from a Sora or another rail. While driving home later I realized the call had probably come from a Common Moorhen. After checking my CD’s, I was back at the former blind first thing the next morning. After a wait of a half hour or so, the call came again from the area of the control structure, and I was confident of the identification at that point. Fortunately John Hoye was recording the Least Bitterns at the time and caught the call on tape. Of course, when you don’t see your bird, you’re not absolutely certain, so it was with some relief when, starting on June 13th, two Common Moorhens were seen fairly often on the banks of the North Pool Dike, right beside the concrete structure. If there were one of each kind in the pair we may be in luck again. Sightings of moorhens from this spot continued through the period.
American
Bittern, Massachusetts Endangered
Species
American Bitterns put on a wonderful performance from North Pool this spring. Unlike the other birds reported on above, American Bitterns are not particularly rare on the refuge, but the appearance of two, and probably three, thunder-pumping males in North Pool, was a high point of the spring. Starting on April 17th and continuing to around May 17th, American Bitterns were seen and heard from the pool with frequency. One bird was often in the open in North Pool, in the reeds and mud just north of the central dike, fishing, preening, walking with excruciating slowness (as described in Sibley), and especially, performing his thunder-pumping display. At times two birds were pumping simultaneously. Many visitors, birders and non-birders alike, were mesmerized by these displays. After the middle of May sightings of these birds dropped off, though a bird was seen on the edge of North Pool from the North Pool Overlook on June 6th. Again, here’s hoping.
Northern Harrier, Massachusetts Threatened Species
Northern Harriers are common winter residents on Plum Island, but they are extremely rare breeders in Essex County. Two and three summers ago a pair of Northern Harriers successfully nested in North Field near the margin of North Pool. There have been nine sightings of Northern Harriers in May, 2004, five of them from the North Field area. On May 7, 2004, a pair was seen circling North Field. On May 22, 2004, one male and two adult females were seen simultaneously over North Field. One female was carrying food and dropped into the reeds and did not reappear. The other female dropped into the area of the former nest and did not reappear. On May 27, 2004, a female was seen circling in and the settling into the area of the former nest. On May 30, 2004, a female was seen circling a half mile north of North Field. There is therefore evidence for a harrier nest in North Field, and the possibility of a second (harriers are polygamous). Adult female Northern Harriers have been reported on five different days during the first two weeks of June. None of the reports have been from directly over the North Field, where a nest is suspected. The sightings have ranged from the salt marsh south of lot three to the salt marsh out from Bill Forward Pool, so no sightings was more than a half mile or so from North Field.
Blue-winged Teal, former (and now again!) Plum Island breeder
Blue-winged Teals have been resident in North Pool and Bill Forward Pool throughout the period of this report. Up to eight individuals have been seen at once. Most birds seen have been males, though an occasional female is spotted. These are the first breeding season Blue-winged Teals I have observed on Plum Island in over a decade. In the first week of July a female was seen on North Pool escorting four downy young. This may be the first breeding record from Plum Island in fifteen to twenty years.
Tricolored Heron
Continuing a trend that started a couple years back, Tricolored Herons have been making regular appearances at North and Bill Forward Pools this spring and summer. Two of these herons have been frequently seen from the central Hellcat dike. To my knowledge there has been no evidence of courtship or any other breeding-related behavior.
Green Heron, probable North Pool vicinity breeder
A pair of Green Herons has been resident at North Pool this spring and early summer. Early in the spring one of both of the birds called often from deep in the woods a little north of the Goodno Woods area, where I suspect the pair has a nest. I have found one of the birds perched high in a tree off the Marsh Loop, and one or both are occasionally seen from the Hellcat central dike.
Black-crowned Night-Heron, probable North Pool vicinity breeder
Last year there was a small roost of Black-crowned Night-Herons in tall trees about 30 yards south of the former blind location. This year a number of these herons were seen entering the woods a bit further south of this location, and I flushed birds from this area on two occasions this spring. There have also been a number of sightings of these birds flying back and forth over North Pool and the Hellcat woods. Then in late June and early July recently fledged Black-crowned Night-Herons were sighted along the margins of North Pool and in the pans near lot three. I believe these young birds were raised somewhere deep in the Hellcat forest.
Yellow-crowned Night-Heron, rare bird on Plum Island
An adult Yellow-crowned Night-Heron was sighted four times in June, in or near North Field and North Pool. It was first seen on June 11th, and subsequently on the 12th, 13th, and 14th.
Glossy Ibis
One to nine Glossy Ibises have been seen at the north end of North Pool this June and early July, though I know of no evidence of breeding behavior. These birds are likely part of the Kettle Island (off Magnolia) colony. As June moved into July, sightings have become more numerous and the number of individuals has grown.
Virginia Rail, regular North Pool breeder
Virginia Rails are regularly heard from North Pool and occasionally seen from the Marsh Loop trail, and this spring has been no exception. Though evidence of breeding is rarely evident, it is safe to assume that North Pool has a number of housekeeping Virginia Rails.
Marsh Wren, regular North Pool breeder
This breeding season Marsh Wrens are especially abundant throughout the reeds of North Pool and Bill Forward Pool. A nest was located within fifteen feet of the Marsh Loop boardwalk.