REMARKS

Aggregate Total Standard Sightings:

[DAR 5] The aggregate TSS for the survey is conservative, i.e. a significant number of birds visiting the Lake were not counted because of their presence at times when observers were not present or because they were obscured by shore vegetation, rough water or flock-mates.

[DAR 8] TSS, summed for all species peaks in the spring and fall, demonstrates the fall exceeding the spring in 8 out of 9 of the full years surveyed. The average TSS for the spring is 1,786 and 3,234 for the fall. The interesting generalization thus emerges: more species in the spring and more birds in the fall. A feature of the data is the delayed spring peaks for 1992, 1993 and 1994 and a delayed fall peak for 1993 and 1994, again suggesting late ice-out - and the possible influence of the dust clouds of Mount Pinotubo spreading into the northern hemisphere following the explosion of June, 1991. A "pile-up" is also suggested for the spring of 1992. The late fall peaks following late spring peaks for 1993 and 1994 reminds us of the concept of "temporal structure" presented in the work of Anson Koehler (see section 7), however the relatively early fall peak of 1992 is an asperity. We further conjecture that following the two to three year period of reduced insolation the migratory peak returns to middle March and middle November with the clearing of the stratosphere. The large fall peak of 1996 remains unexplained.

[DAR 8] Inspection of the TSS histograms strongly suggests the presence of three modes per year, a major mode in the fall, a lesser early spring mode (both as discussed above) and a minor third mode of mid May to mid June, the latter clearly defined for 1991 through 1997 and weak or unclear for 1988 through 1990. This mode is the consequence of newly hatched Canada Geese, Wood Duck and Mallard entering the count in the 19th through 25th weeks. It is poorly defined for 1988-1990 because of the small number of young birds appearing.

[DAR 8] The nadir for the sum of TSS occurs during the 28th through the 35th week ranging from 6 to 195, the higher values appearing later in the survey and under the influence of the expanding population of Canada Geese now residing during the warmer weeks of the year.

[DAR 9] Peak species diversity of migrants usually occurs during the spring with eight of the nine full years showing maximum weekly diversity during late March and early April. Excluding ten of the resident and sojourning species, peak diversity ranged from 8 to 18 species with the maximum species richness of the survey taking place over the week of 23-29 March, 1997. Peaks of higher species diversity in the fall occurred in October and November. ranging from 4 to 12. Future surveys might well focus on the four months of March, April, October and November to sample waterbird migration at the Lake for both number and species.

[DAR 9] A number of days were quite devoid of migrants (exclusive of residents and sojourners) with 16 of these occurring during the colder weeks 42 through 12 and 16 for the warmer weeks 21 through 35 for the entire survey.

[DAR 10] On a weekly basis, the Mallard is not only abundant but it is frequent, in the sense that it appeared during every week of 1990, 51 times in both 1996 and 1997, and, with an average of 46.6 weeks for the nine full years of the survey. Quite often, more than 25 individuals were noted on a daily basis. The Great Blue Heron, on the other hand, was frequent but never abundant appearing during 51 weeks of 1995 and with an average weekly occurrence of 43.0 for the nine full years, but only rarely with more than five individuals present daily. The Ring-billed Gull, Canada Goose, Belted Kingfisher, Wood Duck, American Black Duck and Herring Gull were also "frequent" appearing on average more than 50% of the weeks of the nine full years.

A clear increase in frequency is evident for the Canada Goose with the average frequency for the four years of 1989 through 1992 being 33.8 weeks (range 25-38) and the four years of 1994 through 1997 (range 36-46) being 43.3 weeks, an increase of about 28%. The Belted Kingfisher, in contrast, declined, the fours years of 1989 through 1992 (range 39-48) having an average of 43.8 weeks and the last four years (1994-1997) with the reduced average of 29.8 weeks, a decline of 32%. The Herring Gull suggests a slight decline. The five other species showing relatively high frequency indicate little or no trend over the ten years of the survey.

As might be expected, each of the eight "frequent" species were seen to feed at the Lake and its drain, Collins Creek, for much of the year and, with the exception of the two gull species, nested at or near the Lake.

[DAR 7] Waterbirds observed during the survey were divided into four categories, with one of these subdivided.:

• Year-around Residents:
  • (Mallard, Black Duck, Great Blue Heron, Belted Kingfisher, Canada Goose)**

• Summer Residents:
  • (Wood Duck, Green Heron, Black-crowned Night-Heron, Double-crested Cormorant)**

• Migrants:
  • Sojourning (residing for several weeks or more):
    • (Common Merganser, Hooded Merganser, American Wigeon, Gadwall, Ring-necked Duck, Green-winged Teal, Herring Gull, Ring-billed Gull, Great Black-backed Gull, Great Egret, Pied-billed Grebe, Killdeer)

  • Express (residing for three days or less):
    • (Bufflehead, Red-necked Grebe, Horned Grebe, Ruddy Duck, Common Loon, Northern Shoveler, Canvasback, Northern Pintail, Common Goldeneye, Blue-winged Teal, Snow Goose)

• Accidentals
  • (Bar-headed Goose, Barnacle Goose, Mandarin Duck, Bald Eagle, Brant)

[DAR 2] The significant number and species diversity of waterbird sightings at the Lake came as a surprise to both the residents and long-term students of this highly urban and heavily used Lake. Arrival of large numbers of waterbirds after sunset when human vision (without binoculars or spotting scope) is inadequate, along with the increase in numbers of the Canada goose, are the bases for a notable percentage of the counts reported.

[DAR 7] The Pied-billed Grebe sojourns regularly for the spring migration and less so for the fall but several prolonged fall visits (1989, 1995, 1997) suggest that the Lake serves as a food base. Summer visitation also occurs (7/10 years) suggesting that there may be local nesting. Special attention must be given not to overlook this bird which spends much time under water.

[DAR 7] Although uncommon at Collins Lake, numbers of Double-crested Cormorant appear to be on the rise. Average annual TSS for the first four years (1988-1991) of the survey is 17.8 (range 3-37 TSS) while that for the last four years (1994-1998) is 88 (range 31-173 TSS), an increase of almost 5 times. Notable is the regular arrival during the 14th week for 1992 through 1998 - with 1997 excepted, the arrival taking place one week earlier. The last birds are seen during the 35th through 47th week. Visiting birds feed vigorously under the water at the Lake and may be missed by an impatient observer. Resting birds perch on the Island and north shore and some overnighting occurs in the crowns of tall trees on the Island. Examples of the species may be found during the warmer months at the dams and waterfalls of the Lower Mohawk River but nesting colonies are not yet established.

[DAR 7] The Great Blue Heron is one of the most regular residents of the Lake occurring throughout the year with the exception of a hiatus for May and June. Open water maintained by warm-water spring flow is crucial to use during the winter months. An explanation for the two month hiatus is not yet available; nesting seems an obvious answer but immature birds are missing from the Lake as well.

[DAR 7] The Green Heron, also called the Green-backed Heron, appears in small numbers during the 13th to 25th week. During the 35th to 43rd week sightings increase in both number and regularity with the peak week ranging from the 29th to the 37th week to be followed by the fall departure during the 35th to 43rd week. TSS range from 23 to 133 without trend. The Green Heron feeds in the shadows and among the vegetation of the Lake shore and thus is easly missed. We most commonly detected its presence by its shreik and flight from place to place across the Lake.

[DAR 7] The Black-crowned Night Heron is an uncommon summer resident appearing as early as the 14th week (e.g. 1992) and remaining until as late as the 43rd week (e.g. 1989). TSS range from 0 (1990) to 25 (1989). The last nesting colony of the species in the Mohawk Valley (near the route 9 bridge) was destroyed by a gunman in the 1950s and a new colonies have failed to form since then. Scotia Island located in the center of Collins Lake appears to be an ideal site for a heronry but but there have been no signs of such an establishment during the survey.

[DAR 5] The Canada Goose record demonstrates an exceptional increase with TSS of 135 for 1988 rising to an average value for the three years of 1995 (18,353), 1996 (12,650), and 1997 (17,059), of slightly more than 16,000, an increase of 118 times. Nesting began on the Island in 1989 and continued for the rest of the survey "saturating" the nesting site with six to eight nests. The masters study by Jody Rose, The Establishment and Subsequent Nine-Year Daily Study of the Canada Goose (Branta canadensis) at Collins Lake, Scotia, New York, with Particular Focus on 1KA, a Banded Female , (1998), details the increase.

The Canada Goose remains in our region during dry winters depending heavily upon exposed yellow feed corn, spilled on the fields during harvest, and the grasses and forbes of snow-free hay fields, lawns and golf courses. Winters with a prolonged, heavy, snow pack prevent feeding and force the geese to move southwards to areas of better grazing. Winter overnighting of large flocks of Canada Geese occurs at Tomhannock Reservoir, Town of Pittstown, Rensselaer County and Vly Creek Reservoir, Town of New Scotland, Albany County. At these reservoirs the geese maintain areas of open water, usually of an acre or more in extent throughout the winter. An example, on the 6th of February, 1992, with air temperature of 10 degrees F, Carl George, Jeff Nield and John Torgan measured ice thickness of the sheet surrounding a two-acre open at the north end of Tomhannock Reservoir finding depths ranging from 12 to 15 inches. Different feeding schedules for the various family units result in the presence of a sufficient numbers of birds at the "open" to keep it ice-free around the clock. Curiously, the perimeter of the open was relatively free of guano in spite of the fact that several thousand Canada Geese had regularly used the site for more than seven weeks.

[DAR 7] The Wood Duck ranks sixth in sightings with 16,553 TSS. Annual TSS range from 656 (1989) to 4,010 (1995). Examples arrive during the 9th through 14th weeks with the last birds departing during the 42nd through 49th weeks. Typically, the species histogram is trimodal with the major mode being either in the late spring (Peak Week 21-26) or fall (Peak Week 39-44) and the lesser mode in the early spring. The first "pre-brood" mode is comprised mostly of migrants, the second "brood" mode of brooding females with young and the third "post-brood" mode of overnighting fall migrants. Nesting of this summer resident occurs in the hollows of large, old trees along the north shore of the Lake. The curly-leafed pondweed (Potamogeton crispus), the associated duck weed and invertebrates, are important foods for the hens and their ducklings of late spring. There is a slight trend for increased abundance with the average TSS for 1989-1992 being 5760 and the average TSS for 1994-1997 being 9382. We suspect this to be linked to a regional epidemic of rabies which has greatly reduced numbers of the raccoon, an important nest predator for this species. No clear trends are evident for times of passage. See the thesis (Master of Arts in Teaching) of Jennifer Carman: Significant Events During a Nine-year Daily Survey of the Wood Duck at Collins Lake, Scotia, New York, 1996, available through Schaffer Library, Union College.

[DAR 7] The Mallard was one of the more difficult species to count well in the survey. The majority of annual TSS occurs in the fall as birds are displaced from smaller ponds and marshes by night ice formation, a process we call "compression". The onset of vespertine arrival occurs from week 37 through 40 (1988 excluded because of inadequate survey), peaking in week 45 through 49 and ending with the completion of ice cover. The difficulty of the count is based on the fact that the birds arrive about 20-30 minutes after sunset when light levels have fallen to the extent that unaided human vision is inadequate to the task, and especially by the more senior observer with reduced night vision. We became aware of the large number of Mallard arriving in the fall evenings in 1989 and attempted thereafter to field two observers on each fall night for this often cold and challenging process, one observer sighting, using binoculars, and the other recording. Refinement of the procedure eventually allowed us to make reasonably reliable counts for 1994 through 1997, the latter year peak week yielding 1,927 TSS - or about 275 birds per night. Another problem in the count was the difficulty of segregating Black Duck from Mallard at low light levels. Withoubt doubt we underestimate Black Duck in the Survey. A slight increasing trend for Mallard is evident in the data however this may be a result of improved survey technique. See the honors thesis by Matt Forster and Jennifer Wall available through Schaffer Library of Union College: Evening Aggregation of Mallard and Black Duck at Collins Lake, Village of Scotia, Schenectady County, New York, 1995.

Vespertine arrival of Mallard at Collins Lake usually occurs in pairs and small flocks and from all directions with most birds settling in the middle waters south of the Island. After a brief period in this sector the birds swim to the southern edges of the Lake to enter a cattail and purple loosestrife marsh until their departure the next day - well before sunrise. Such a regime has concealed the importance of the Lake for this prominent waterfowl species and may explain the presence of large number of lead shot in the surficial sediments - the birds transporting it to the Lake after collecting it, without apparent morbidity. See the study by Carl George: Long-buried Lead Shot: Stability, Possible Transport by Waterfowl and Reexposure by Hydrualic Dredging, Collins Lake, Schenectady Couty, New York, May 1993 Technical Report, Division of Fish and Wildlife, NYS Department of Environmental Conservation.

The sighting of broods of Mallard assures us that the marshy perimeter provides nesting for the species while feeding over the spring beds of curly-leaf pondweed suggests an adequate nutritional base for the early phases of rearing. After the demise of the pondweed in June the Mallard revert to benthic feeding in the shallows.

The Mallard is a year-around resident of the Lake occurring during the day even in deep winter when the only open waters are those of the springs along the north shore and in the outlet stream. Elsewhere in the region, below falls and dams and in thermal plumes of cooling waters, Mallard overnight during the coldest of winter weather deicing their plumage by repeated submergence. It seems important to remember the importance of hydroengineering in the eastern expansion of this initially western species.

[DAR 7] The Gadwall appears every year of the survey but always in small numbers - the largest TSS being in 1992 with 47 sightings. The spring passage dominates with only two fall records in week 41 of 1989 and week 44 of 1995. And, the spring visits are often quite early, e.g. 7th week for 1989, 8th week for 1991, 8th week for 1993 and 5th week for 1996. It associates with the Ring-necked Duck and American Wigeon depending upon the vigorous spring growth of the Curly-leafed Pondweed (Potamogeton crispus). The paucity of the fall biomass of this macrophyte probably explains the absence of the Gadwall in the fall.

[DAR 7] The American Wigeon is a good example of a spring-only migrant at the Lake appearing during the 8th through 19th week and with 924 TSS summed for 11 springs.. The fall, in great contrast, yielded only one pair on the calm moonlit evening of 25 October, 1996. The spring migration of 1992 suggested a "pile-up" with 331 TSS accumulated over 8 days, the longest stay of the species for the survey; perhaps the consequence of delayed ice-off on their breeding grounds to the north. The spring-only visitiation of this herbivorous species is probably linked to the annual life cycle of the curly-leaf pondweed (Potamogeton crispus). This plant vegetates vigorously in the early spring reaching a density, at the time of flowering in May, of about 300 grams (oven-dry weight) per square meter. Following fruiting, senescence and decay reduces the great mass of plant matter to a few grams per square meter in early June. Germination from turions begins in August but biomass remains below ten grams (ODW) through December - too little to attract visitation by herbivores. The American wigeon regularly feeds on curly-leaf pondweed restricting much of its activity to the waters above the pondweed beds. See the work of Peter Tobiessen and Phillip Snow this aggressive alien macrophyte: Temperature and light effects on the growth of Potamogeton crispus in Collins Lake, New York State. Canadian Journal of Botany, 62:2822-2826.

[DAR 7] American Wigeon regularly associates with Ring-necked Duck at the Lake gleaning fragments of curly-leafed pondweed brought to the surface by the diving of the Ri ng-necked Duck.

[DAR 7] The Ring-necked Duck is primarily a spring migrant arriving with the appearance of open water at the Lake during the 10th through the 14th weeks. The asymmetry of the spring histogram with a strong onset and a series of minor cells following is common for this sojourning species. We interpret such a configuration as migration shaped by physical factors, in this case new access to open water. The sojourn is one to seven weeks, but typically three to five, most of which are spent over the beds of curly-leafed pondweed (Potamogeton crispus) in association with other herbivores such as the American Wigeon, Gadwall and Canada Goose. TSS of more than 800 for the spring of 1992 - much greater than the average of 240 TSS - suggests a "pile-u p", again possibly attributed to delayed melting of ice of breeding wetlands required by the species - this in turn linked to reduced insolation resulting from the explosion of Mount Pinotubo in June, 1991. An irregularity was the early peak-week arrival (11th week) relative to ice-out in 1992 which was delayed to the 8th of April. A second was the late peak-week arrival of the 1994 (14th week) when ice out was on the 20th of March. One could conjecture that the flock leaders were remembering the time of ice out the prior year and adjusting accordingly. There is some support for this idea using the data at hand. Fall visitation is meager usually occuring during the 43rd through 45th weeks, but fully absent in 1991, 1993, 1994 and 1997. This is explained by the paucity of the important food base, the curly-leafed pondweed in the late fall.

[DAR 7] The Bufflehead occurs regularly but in small numbers appearing every year of the survey; 22 days in the spring (weeks 11 - 20) and 20 days in the fall (weeks 41-47). The regularity emerges best in the fall when Bufflehead were found during the 43rd, 44th or 45th week during each of the ten falls surveyed. It is possible that the same birds pass through in both the spring and the fall.

[DAR 7] The Common Merganser was one of the ecologically more important sojourning species. The first spring arrivals appeared during the 10th to 15th week (ave. 10.3) with the average peak week following two weeks later (ave. 12.3), in turn followed an average of 3.1 weeks later during the 15th week (ave. 15.4). Fall migration was generally larger exceeding that of the corresponding spring from 2.6 to 64 times, the only exception being the spring of 1992.

[DAR 7] We suggest that the increased numbers of Common Merganser for the peak week of 1992 to be the result of the explosion of Mount Pinatubo in the Philippines in June of 1991! Millions of tons of particulate matter were injected into the stratosphere causing widespread reduced insolation in the northern hemisphere with delayed melting of the breeding wetlands of the Common Merganser in northern New York and Canada. We record the resulting "pile-up" at Collins Lake along with prolonged ice cover and the delayed departure during the 18th week.

[DAR 7] Fall visitation of the Common Merganser begins in the latter part of October (ave 43.1) peaking an average of 3.6 weeks later during November (ave. 46.7) with the final departure averaging 3.1 weeks later in December (ave. 49.8). The dissimilarity of the TSS for the spring and fall is evidence for a migrational "lane change". For further consideration of the migration of the species see the honors thesis of Christine LeDuc, Migration of the Common Merganser (Mergus merganser): a Nine-year Study at Collins Lake, Schenectady County, New York , (1997), available at Schaffer Library, Union College.

[DAR 7] The extent of symmetry for the histograms depicting the passages of the Common Merganser (and other species as well) may indicate the contrasting influences of extrinsic and instrinsic mechanisms - "J-shaped" or asymmmetrical histograms, e.g. fall of 1989, indicating physical constraints such as ice cover while a symmetrical array of histogram cells, e.g. fall of 1995, may suggest control by neurohormonal mechanisms.

[DAR 7] The Common Merganser fishes vigorously at Collins Lake during both its spring and fall sojourns probably impacting the Lake’s fish fauna greatly. In example, if we select the 1995 fall passage of the Common Merganser extending over 7 weeks with a TSS of 2,852 and estmate consumption of 10 fish per Standard Sighting (well within known stomach analyses) the harvest is approximated at about 28,000 fish, a major challenge for the fish populations of the Lake!

[DAR 7] The Killdeer appears during the 10th through 19th week and departs during the 41st through 46th, peaking erratically during the 29th through 42nd weeks. The Killdeer was included in the survey as a waterbird because of its frequent occurrence on the sandy shores of the southwestern shore of the Lake but in 1995 we extended the survey area to include the lawns of the Park thus increasing the annual TSS and giving us a better sense of passage times; in example, the histograms for 1995 (1,914 TSS) and 1996 (985 TSS) are clearly bimodal, the first mode suggesting the incursion of regionally foraging Killdeer and the second mode the passage of a wave of migrants originating to the north, these arriving after the departure of the regional population. Summer and fall Killdeer usually forage on the lawns in loose flocks. Killdeer nested on Park grounds but most nests were discovered and destroyed by visitors or overrun by lawn maintenance vehicles.

[DAR 7] The Spotted Sandpiper is a warm-weather resident arriving about the 16th week (e.g. 1992, 1993 and 1996) and departing as late as the 40th week (e.g. 1993). Annual TSS are low ranging from 5 to 32 and, along with the many gaps in the histograms, suggest extensive oversight of this small and well camouflaged bird. It probably visits the Lake much more frequently than out data suggest. Neither nests nor young have been observed at the Lake.

[DAR 5] Several regional landfills closed during the study period and the loss of this scavenging base is proposed as an explanation for the observed decline of Herring Gull numbers. The first four years of the survey yielded TSS of 13,575 (Ave. 3,394, range 2,385 - 6,807) while the last four yielded 4,355 (Ave. 1,089, range 417 - 1,948). See the honors thesis of Sara B. Gower for a discussion of the three common gulls encountered in the survey: A Ten-Year-Survey of the Great Black-backed Gull (Larus marinus), Herring Gull (Larus argentatus), and Ring-billed Gull (Larus delawarensis) at Collins Lake, Schenectady County, New York, 1998, available through Schaffer Library, Union College.

[DAR 5] Of the three common species of gull, the Ring-billed Gull predominated.Its noisy flocks gathered at the Lake in the spring and fall often harvesting large numbers of young (c. 10 cm TL), cold-stunned, gizzard shad from the shallows.

[DAR 5] Three species of gull, Ring-billed Gull, Herring Gull, and Great Black-backed Gull, spend their days at the Lake arriving from, and departing to the east. Tracking of this diel migration found the primary evening terminus at the north end of Tomhannock Reservoir, northeast of Troy, NY and about 20 miles due east of Collins Lake.

[DAR 5] Herring Gull commonly associated with feeding Common Merganser attempting (but rarely succeeding) in the stealing of the fish caught by the mergansers.

[DAR 5] Great Black-backed Gull visited the Lake more frequently to scavenge during periods of die-off by the Gizzard Shad (Dorosoma cepedianum). This member of the herring family is introduced and commonly reaches a total length of 12 inches (c. 30 cm). A major die-off occurred during the late winter of 1988 especially large numbers of Great Black-back Gull.

[DAR 7] The Belted Kingfisher is a year-around resident appearing in the dead of winter over the open waters of Collins Creek, the discharge of the Lake, and in the calm of July and August when its young learn the skills of fishing. The summer weeks of 1989, 1990, 1995, 1996 and 1997 demonstrate successful nesting especially well. TSS fell to only 25 in 1993 while peaking in 1990 with 187.