Background Information On Nighthawk Migration

The most complex and inexplicable case of a declining species in the northeast is afforded by the Nighthawk, a common bird ranging widely throughout the continent. Certain details of its life history must be given to appreciate the facts of its history.

1. A very powerful flier, feeding exclusively on the wing by catching flying insects.

2. A tremendous migration route; the majority winter south of the equator, and do not stop on migration;freely crossing the Gulf of Mexico and parts of the Caribbean Sea.

3. Breeding on the grounds in plains, prairies, barren pastures, stony hillsides, and sandy pine barrens. It is consequently most numerous in the plains and prairie states and those with pine barrens.

1600	If present at all, presumably rare and local in the primevil forests of the whole northeast.
1650-1850	A presumed great increase with the clearing of the forests.
1850-1900	Common summer resident north to Cape Breton Island, according to the local incidence of the required breeding sites. In Massachusetts common in the pine barrens of the coastal plain, more local in the interior, but reported as nesting in every local area. Common on migration in spring, often abundant in flocks of hundreds in fall.
1903	Numbers decimated by the prolonged cold rains in June. The bird is almost exterminated as a ground-nesting species in the whole state, in greatly decreased numbers on migration. It never recovers.
1895-1920	To the intense astonishment of ornithologists, the bird abandons its ground-nesting habits from Philadelphia to Cape Breton Island, and nests exclusively on flat city and town roofs.
1920-1945	(a) The species begins to abandon city roofs, and therefore disappears or decreases as a summer resident. (b) Migrants become scarcer and scarcer near the coast. On Cape Cod it is now one of the rarest of fall migrants. (c) The species continues its abandonment of ground-nesting habits in pine barrens throughout the east. Cruickshank (1942) reports a 70 percent decrease on Long Island. Alex Sprunt, Jr, tells me of its inexplicable disappearance from coastal South Carolina, where it was formerly a common summer resident. (d) No change in northern New England to Cape Breton is reported. The species is, therefore, still fairly common on migration south on the coast to Cape Rosier, Maine, and inland in the Connecticut River Valley....

Steadily decreasing; formerly a common summer resident, last nesting in 1887; a regular transient, formerly common, now in very small numbers.

1907	Last fall flight in numbers; on September 6, flocks of 14, 18, 75, and 100 passing over the river (William Brewster).
1928-1948	Modern observers rarely see an occasional flock of 12 to 15

[Nighthawk migration] is still common in the inland river valleys when flocks of 200-300 and occasionally 500 are still seen in August and early September.

The fall migration is unusually predictable and peaks during the last week of August and the first week in September. Flocks of three to twenty birds are typical at this time. Consistent field work during the peak of the fall migration would, no doubt, yield higher totals for this species.

Like many things that have to do with bird migration, SOME things are known but much more needs to be learned. Here in Worcester County, people like Bart Kamp and Fran McMenemy have been watching nighthawk migration for many decades. Out in the Valley, ditto for folks like Seth Kellogg and Tom Gagnon.

Some of the things I have learned in these parts (Worcester County) in the last 25+ years include:

1. Nighthawks seem to move along established "flight lines". This is also mentioned in other sources like Nigel Cleere's NIGHTJARS.

2. Often (at least here in Worcester County) these flight lines seem to follow rivers or chains of ponds and reservoirs. This makes sense because concentrations of flying insects are around these areas.

3. The largest movements are associated with BIG flights of certain species of flying ants. On days when you go out and find flying ants on your windshield and see them about in the air, generally coincides with big flights of nighthawks. On nights like this, if you train a scope over the city, you can see large "balls" of nighthawks furiously feeding on the ants in the late afternoon, BEFORE they start to move. Sometimes Ring-billed Gulls are seen also aerially feeding in the same area. Bart often watches for ants to be enlarging their holes in preparation for these flights to predict when a good nighthawk flight will be. These days are usually warm and muggy, but not always.

4. The ovement of flocks, in Worcester at least, can be very complex. Sometimes flocks move over with a purpose, birds really flying quickly and directly. Other times, they move in rising, feeding circling flocks which move south, but then can drift back. And sometimes only part of the flock drifts back...it can be very frustrating when you are trying to count these birds. Sometimes flocks drift south and then north again several times throughout one evening.

5. Wind, especially from the south, can be bad for seeing large flocks of migrating nighthawks, though (perhaps) they are migrating lower. Or, they take different flight lines.

6. Sometimes activity seems to slow down as real dark approaches, but it is difficult to say really what is going on, as our ability to clearly see is hampered. It is interesting that on several occasions, when it starts to get really dark, I have seen single migrating nighthawks moving very low over tree tops and moving with a purpose.

7. Nighthawks DO move at other times of the day, and I have seen small flocks moving at all times of the day, and have often seen single bird migrating low and fast at dawn. However, the biggest movements are typically (though not always) late afternoon and early evening.

8. The largest numbers of nighthawks migrating are reported from inland locations. Well inland, say from Worcester County through the Valley. Many times the birds are heading south or southwest.

What is amazing is that more birders do not invest some time in doing more systematic observations of this incredible avian phenomena that happens in our back yard. I find it every bit as interesting as hawkwatching. Here in the County, we are planning on doing systematic multisite observations of nighthawks in the Blackstone Corridor starting next year. It would certainly be invaluable to coordinate certain nights of watching nighthawks across the state on a yearly basis, getting certain recognized sites manned on a regular basis instead of the haphazard observations that are going on now.

Massachusetts Audubon started a Nighthawk watch in the late 70's.  The watch would start on August 20th and end on September 7th.  Following these dates, I have continued my watch from the same post for the past 24 years.  Before that I use to watch from the roof of my shed until the neighbors trees grew too tall. In the year 2000 I recorded my all time low number of birds sighted, 1,395. For the previous 22 years I had AVERAGED 3,680 birds.  So my 2000 sightings were off by 63%. This year, 2001 I recorded only 1,340 birds.  This is off by still roughly 63% from the first 22 years at this post. Checking past records my best year was 1981 when I recorded 7,028 birds.  As recently as 1995 I recorded 5,898 birds.  My best single evening was in 1991 on August 22, 3,673 birds.  Over the years I have recorded many evenings over 1000 birds.

There are many questions and no clear cut answers as to what has happened.

1) Poor breeding year on the tundra.

2) Taking a different migration route.

3) Poor ant hatch in the valley here.

4) Poor weather (this year I nighthawk every evening, no rain).

5) Something happening on their winter grounds, the pampas of Argentina.

In any case for 2 years in a row I have recorded record low counts and in 1999 I only had 1,850, not far off a low at that point. Does anyone know of other parts of the county where nighthawk watching occurs?  What are they recording?  A few years back someone told me there were counters in Virginia. If you have any information on other counts, please email me direct.

Lonely is the vigil of the nighthawker but the rewards are so great.

Tom Gagnon Florence, Massachusetts.

The Nighthawk usually sleeps during the brighter part of the day, resting on the ground, a rock, a fence rail or a bough. Often it sits silent on a large limb, where it might be mistaken for an excrescence or a bunch of gray lichens. During the nesting season, however, it keeps very irregular hours; frequently it hunts in daylight, and may sleep in the darker part of the night, but at times it is heard on the wing far into the night. Breeding in cities is a comparatively recent custom and dates from the introduction of flat tar roofs. These arid spaces seem to suit the bird, and it hawks about high over the city roofs, seeking its insect prey.

Late in August the southward movement of the Nighthawks begins, and it continues intermittently through the greater part of September. Unlike the nocturnal migrations of most of our small land birds, the travels of the Nighthawk are made by day. The birds are seen commonly passing southward along some river valley in numbers from a score to a hundred or more in loose scattered flocks, flying about in a leisurely manner at no great height above the ground or water, and catching insects as they go. These flocks sometimes rest during a part of the day, either on the ground or in trees on rough and rocky ground, and if undisturbed begin their journey toward evening, first filling their stomachs as they go.

When the flocks are feeding, they do not always move southward, and sometimes they have been observed to travel in exactly the opposite direction. There are certain routes over water which are followed by them, and which take them far off from the direct southwesterly course. But the general movement trends southward.

The food of the Eastern Nighthawk apparently consists entirely of insects. Its large stomach often is packed with them, and its gullet also and even its mouth may be filled with them when about to feed its young. Its insect food is so varied that it is impossible to enumerate it. Apparently it takes any insect that flies, from tiny gnats to the largest moths.... [The Nighthawk's] mouth, like that of the Whip-poor-will [a close relative], opens far back under its ears and forms a yawning trap to engulf unwary insects, while its long and powerful wings enable it to overtake them with ease.

In the fall of 2003 our observers recorded a total of 1,263 migrants at 20+ locations along the Assabet, Sudbury, and Concord Rivers in the period between Agust 13 and September 18, 2003. The peak day was August 26 when 649 nighthawks were reported with one massive flock of at least 535 birds observed along the headwaters of the Assabet in southwest Westborough. One of the Westborough observers reported that the flock extended to the horizon in all directions and that they likely undercounted the flock significantly.

The fact that only 114 nighthawks were observed by all of our other observers at various other locations along the three rivers that day obviously raised a question as to where the Westorough flock had come from. Early on in our surveying efforts we had assumed that our migrants had come down the Merrimack through New Hampshire and then at Lowell had picked up the Concord River when the Merrimack turned east towards the sea. Then in 2001 Steve Moore offered an alternative hypothesis when we learned that substantial numbers of nighthawks were being observed moving up the Merrimack towards Lawrence and Lowell. Based on his experience as a youth of seeing large flocks of nighthawks migrating south along the Maine coast, Steve hypothsized that some of these birds may have turned southwest up the Merrimack at Newburyport to Lowell and then up (south) the Concord River.

But if our migrants come from Lowell as hypothsized, why was last year's massive flight at Westborough on August 26 not picked up by our various other observers who were spread out along the three SuAsCo rivers? No such flock was reported from the east of us where there are substantial number of observers in such places as Boston, Cambridge, Brookline, and Newton. But what about the Nashua Valley area to the northwest of us around Harvard, Lancaster, Leominster where there have been very few nighhawk observers in the past? This year, in an effort to answer that question, we have added the Nashua River Valley to our coverage area and have enlisted the support of the Friends of the Oxbows National Wildlife Refuge.

Formerly common across Canada, this species has completely disappeared from parts of its range (particularly urban centres) and declined in others. Breeding Bird Survey data show a 3.9 % annual decline of 30 years steepening to a 9.5 % annual decline in the last decade. This would translate into an overall population decline of 70 % over 30 years and 63 % over 10 years. Ontario Breeding Bird Atlas data show a 58 % decline in distribution in the last 20 years. About 25 % of the world population nests in Canada.

Nighthawks counts in 2006 far exceeded those of recent years in six of the eight watersheds surveyed as well as the survey area as a whole. Forty-six sites in seven watersheds between the Merrimack, Concord, and Sudbury Rivers on the East and the Connecticut River on the West in the upper two-thirds of MA and the lower one-third of New Hampshire reported a total of 7,081 migrating and/or feeding nighthawks in 2006. The 7,081 total was up 380 percent over 2005, 422 percent over 2004, and 562 percent over 2003. And these increases were despite the unavailability of four of our long term observers and sites year in the Connecticut and SuAsCo watersheds!

The percentage increases varied widely among the various watersheds. In the SuAsCo watershed the 953 birds seen in 2006 were up a "mere" 181 percent from 2005 and were actually down 24 percent from 2003. On the other hand, the Nashua River totals in 2006 were up 445 percent over 2005 and the aggregate totals for the other reporting watersheds were up an even greater 514 percent versus 2005. The decline in counts in the SuAsCo watershed between 2003 and 2006 reflected a continuation of the long term decline in numbers of nighthawks migrating throughout Eastern Massachusetts over the past century. Analysis of the seemingly slow but steady westward march of this downward slide has always been a primary focus of our survey.

Why the big uptick in our overall count numbers in 2006? Certainly one possible cause was the unusually wet summer in the northeastern part of the US and eastern Canada. Statistical analyses of populations of some boreal species have shown a relatively strong correlation between precipitation levels and breeding success and this could well apply to nighthawks as well. The fact that this year's peak counts were almost a week later than normal could also suggest a significant increase in the numbers of first year birds. The wetter weather could also have had an impact on flying ant populations though reports of flying ants did not appear to be up from prior years.