Winter of 2002

Winter of 2002 - 2003

This material supplements Maury's earlier articles:
What do the changes mean? (January 2002)
Worms, fish, birds, mammals and the Harbor clean-up (November 1997)
Early Winter TASL Census Results (January 1997)

See also1980 - 2003 summary tables

Species summary

Is the Harbor cleaner?

Fall weather patterns

The big picture

Back to the birds

Fall and winter seasons this year have been far different from last year, weatherwise and, to some extent, birdwise. While we were not able to do a TASL count in November, I got out to several areas (Winthrop, Boston, part of Squantum, and Weymouth) at the end of the month to get some sample counts. My counts indicated many species were below average as compared to our typical fall counts (see Table of November counts). In addition, the nighttime wintering duck roost off Carson Beach had a high count of only 800 birds, mainly Red Breasted Mergansers, Bufflehead and Common Goldeneyes, along with some grebes and scoters. This is well below the 1200 - 3000 roosting birds we have seen there over the past several winters. (See The big roost)

The counts from our January 19th TASL count tended to be low for several species (see Table of January totals). In comparing this years data to past TASL counts keep in mind the following:

A small number of sites (5 or 6) are currently visited that were not included in the TASL count routes during the 1980s.

Deer and Long Islands were not always accessible during the 1980s and early 1990s.

Many census routes are now split among multiple parties, providing more observation time and more eyes per stop.

Bad weather was assumed for TASL counts during the 1980s. However, many counts over the past decade occurred during what was considered unusually balmy conditions.

All these factors suggest that early TASL counts may have underestimated bird numbers as compared to more recent years, particularly during years when Deer Island or Long Island was not visited. Therefore, downward trends in the numbers are probably even more marked than the data suggests, while upward trends need to be evaluated very closely for bias resulting from the factors above.

Species summary
(January 2003 census)

Red-throated Loons and Horned Grebes, while their numbers appear to have increased from 1998 onwards, were fewer this year, just as they were during January 2001. Similarly, cormorant numbers were very low, continuing an apparent long term decrease since the early 1980s. Brant numbers were the lowest of any January TASL count, also continuing an apparent decrease in numbers since the 1980s. Red-breasted Mergansers and Common Eider also were on the low side this January. Common Goldeneye and Bufflehead numbers were average but well below their peak abundances in 1989 - 1991.

Mute Swan counts remain higher than the early 1980s. Canada Goose numbers, while down from the past few years, were still higher than counts in the 1980s and early 1990s. Counts of American Black Duck were up from the past couple of years but remain well below numbers observed in the 1980s.

This is the second consecutive year that the January count has had Greater Scaup numbers nearing the levels seen in the early 1980s. During the mid 1990s they seemed on a trajectory to disappear from the harbor.

Scoter numbers were among the highest we have seen in January. They appear to have increased since the mid-1990s. Since scoters are often reported from Deer and Long Islands as well as Hull, this is one species that may have been undercounted during the early TASL years. Still the increase is so substantial that it is likely to be real.

Bonaparte's Gulls were absent for the second year in a row. This is likely due to the diversion of the MWRA wastewater discharge from Deer Island to offshore. Hundreds of Bonies were observed off Nahant during November, but they seemed to have bypassed the Harbor as they moved south.

Is the Harbor cleaner?

Do this year's results tell us anything? Does anything tell us about this year's results? Can we explain the apparent increases, decreases or changes from one year to the next?

In fall 2000 the effluent from the Greater Boston sewage system at Deer Island was diverted to the new under-ocean pipe which took it 9 miles out into Massachusetts Bay. An early expectation among some was that there would be changes in water bird populations as a result of this Harbor "clean-up". You might have heard it reported a year ago that in 2001 the Harbor waters were less turbid (clearer) and that the removal of sewage-borne nutrients led to reductions in phytoplankton.

Yet conditions in 2002 were altogether different. Water clarity and chlorophyll concentrations were similar to what was commonly observed in the 1990s. (Chlorophyll is a measure of phytoplankton concentrations.)

It is increasingly apparent to researchers that the marine coastal ecosystem is extremely complex and unpredictable. It seems likely that the ecosystem changes as a result of the Boston Harbor cleanup will be subtle and likely take several more years to document. It seems less and less likely that we will see any obvious impact on wintering waterfowl populations.

Fall weather patterns

As I noted in a previous article (What do the changes mean?), fall 2000 stood out at the time as unique because of the huge fall coastal phytoplankton bloom that apparently drew millions of bait fish in close to shore. Presumably in response to the abundant food source, Humpback Whales were seen in larger than usual numbers inshore (for example, in Boston Harbor and Salem Sound). Our fall water bird counts that year were among the highest we have observed. Similarly, in 2002 there was a substantial fall phytoplankton bloom along the coast and once again millions of baitfish (herring and menhaden) were observed. In September the fish apparently drew tens of thousands of shearwaters so close to the coast they could be seen from shore off Cape Ann and Plum Island. I observed huge numbers of fish along the docks of Charlestown well into November. Ctenophores, smaller cousins of the moon jelly, were seen, in even higher densities than in 2000, in the Harbor and offshore into early January. With these apparent signs of a plentiful food supply we might have expected good numbers of birds in November. As I indicated above, that does not seem to have been the case.

It seems more likely that birds responded to the storminess we began observing in mid-October. More on this later.

The big picture

The reason we had such an abrupt end to our drought in the fall appears to have been mainly due to El Niño and to the North Atlantic Oscillation (NAO).

As a result of the growing concern about climate change, increasing attention is being given to understanding the role and impact of cycles such as El Niño and NAO on climate. Over the past couple of years there has been a flood of scientific papers linking and correlating a negative or positive phase of the NAO with numerous physical and biological processes in the North Atlantic.

El Niño is discussed in: http://www.intellicast.com/DrDewpoint/Library/1357.

For a good discussion of the factors contributing to this winter's weather and of the NAO go to: http://www.intellicast.com/DrDewpoint/Library/1358/.

Daily and monthly updates of the NAO and other teleconnection indices can be found at: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/all_index.html or ftp://ftp.ncep.noaa.gov/pub/cpc/wd52dg/data/indices/tele_index.nh

El Niño normally brings increased storm activity to the southeastern states. A negative phase of the NAO brings the storms up the east coast and gives us our nor'easters. In mid-October the NAO shifted from positive to negative and remained negative through the middle of January.

A recent paper in the journal Science indicates that another pattern, the Pacific Decadal Oscillation (PDO), has recently changed from a 20 year positive phase to a negative phase (also see http://www.intellicast.com/DrDewpoint/Library/1358/) and with it the entire Pacific ecosystem seems to be changing (fellow Boston area birder Dick Veit has a paper referenced). Similarly, the NAO may be shifting from a predominantly positive to predominantly negative state, possibly bringing with it dramatic changes in the Atlantic system. Information about these changes is preliminary.

One of the bigger questions is: What causes the apparent decadal changes in the NAO or PDO and what is the relationship to global climate change? There is a resurgence in awareness that solar activity may be more a player than previously thought (see Article Library at http://www.intellicast.com/DrDewpoint/Library/1358/). The sun goes through an approximate 22-year cycle, with solar minima and maxima in electromagnetic activity alternating every 11 years. While for decades many researchers have noted an apparent correlation between environmental/ecosystem parameters and the solar cycle there was not a known reason why that should be the case. The difference in solar energy output between minimum and maximum activity is only a fraction of 1%, not enough to have an impact on the productivity of any known biological system.

Recent research has found an unexpected relationship between solar electromagnetic activity and cosmic rays reaching the earth's surface. At the solar maximum the increased electromagnetic activity apparently neutralizes cosmic rays heading for the earth. At the solar minimum there is no such neutralization and we are bombarded with cosmic rays. Increased cosmic rays appear to correlate with the formation of low cloud cover. As a result, less solar radiation (energy) reaches the earth's surface. Increased solar energy during the solar maximum, due to decreased cloud cover, could mean increased ocean temperature at the tropics, which could have some bearing on climate change as well as cycles like the NAO.

We had a solar maximum from 1999 - 2000, and after a decrease in 2001 another up spike in activity in early 2002. The years 1999, 2000, and much of 2002 were dry and mild with high levels of marine productivity. 2001 was noteworthy for its lower levels of productivity. (See earlier comments about the apparent initial response to the diversion of Deer Island effluent offshore.) The scientific community is excited about the potential relationship of the solar cycle and climate changes, but many of the cause and effect links still need to be worked out.

Back to the birds

While the science is interesting, does it tie in with our counts? Probably. There is a body of research that indicates that where birds winter is a trade-off between their being as close to their breeding grounds as possible and assuring that their metabolic needs are being met. We would expect to see a general shift of wintering bird populations south during "bad winters" and north during "mild winters".

I have linked tables of monthly Boston climate conditions over the past 20+ years: November and January. In them I have also included the monthly NAO index (anything over a +1 or -1 is a notable departure from normal). While there are other parameters that I plan to add to these tables, this is a preliminary indication of relative conditions for each TASL count.

Maury Hall

Maury is co-organizer and data-compiler for the TASL winter censuses. He is employed by the Massachusetts Water Resources Authority (MWRA) as staff biologist.