Start of the spring 2017 RMERF season, March 1

MOUNT LORETTE, BEAVER MINES and STEEPLES RAPTOR COUNTS

SPRING 2017

www.eaglewatch.ca
PETER SHERRINGTON

 

Introduction 2017 is the 26th consecutive year that a spring raptor count has been conducted at the Mount Lorette site. In 1992 an eight-day reconnaissance count at the site established that Golden Eagles moved to the northwest in significant numbers through the Rocky Mountain Front Ranges. Most of the birds moved along the Fisher Range, crossing the Kananaskis Valley to Mount Lorette before continuing their migration to the northwest. March 20 will be the exact 25th anniversary of seeing the first migratory Golden Eagles at the Mount Lorette site and there will be a celebration event there to mark the date. A 48 day (393 hour) count at the site in the spring of 1993 yielded 4140 migrating Golden Eagles and the following year a seventy day (649 hour) count produced 4213 birds which remains the highest spring count ever for the species at Mount Lorette. Between 1994 and 2007 extensive spring counts averaging 82 days (897 hours) were conducted at the site with a maximum count in 2005 of 94 days (1238 hours). Despite the steady increase in observer effort during this period, the number of migrating Golden Eagles counted has steadily and significantly decreased since 1995. In 2006 RMERF conducted it first complete fall count at the Piitaistakis-South Livingstone site near the Crowsnest Pass in SW Alberta and in 2008-10 also conducted full spring counts there. During this period extensive comparative counts were made at Mount Lorette between March 1 and April 15 which is coincident with the height of the Golden Eagle migration and during which period over 90% of the population moves north. Observer effort from 2008-10 at Mount Lorette averaged 43 days (487 hours) with a maximum count of 46 days (519 hours) in 2010 when no days were lost to inclement weather. In 2011 and subsequent years the count period was extended by 1 week (March 1 to April 22) and we will use the same period this spring.

Last year’s (2016) spring count saw a combined species passage of 2866 birds that was the second highest since 2006, as was the Golden Eagle count of 2542: it should be noted, however, that all counts from 1993-2006 exceeded these totals. The March combined species count of 2500 represented 87.2% of the total count, while April’s count of 290 was 47.4% below average, but the April total of 290 was 50.8% below average. The maximum Golden Eagle count of 296 on March was the 3rd lowest ever, and 9 days had counts exceeding 100 birds including the second earliest ever on March 7. Five species occurred in significantly higher than average numbers: Northern Harrier (11), Northern Goshawk (11), Red-tailed Hawk (37), Rough-legged Hawk (39) and Merlin (9), while 6 other species were significantly below average. The combined species median passage date was March 18, 5 days earlier than average with 7 species moving earlier than average and just Red-tailed Hawk moving later.

Last year saw the first complete (52 days) count at Beaver Mines which produced 2038 migrants of 17 species: 2 Turkey Vultures, 278 Bald Eagles, 68 Northern Harriers, 98 Sharp-shinned Hawks, 18 Cooper’s Hawks, 60 Northern Goshawks, 9 Broad-winged Hawks, 5 Swainson’s Hawks, 301 Red-tailed Hawks, 6 Ferruginous Hawks, 148 Rough-legged Hawks, 963 Golden Eagles, 10 American Kestrels, 16 Merlins, 9 Gyrfalcons, 11 Peregrine Falcons, and 9 Prairie Falcons. This year will be the third consecutive count at the site which is conducted from Peter Sherrington’s house in Beaver Mines.

Vance Mattson’s 2016 reconnaissance count at the Steeples site on the western flanks of the Rocky Mountains near Cranbrook, BC produced 372 birds of 9 species that included a single day high count of 119 raptors that included 104 Golden Eagles, on March 20. This year will be the eighth consecutive count at the site.

 

Cliff Hanson is again organizing the Mount Lorette count and welcomes visitors to the site. If you are interested in volunteering as a “Skysweeper” (no previous experience needed: just good eyes and binoculars) or as an Observer please contact Cliff at 403- 673-2422. Details of how to find the site and other useful information can be found on our website. Generally the best time to see migrating eagles is in the afternoon, and the chart below gives an indication of the dates when other raptors are expected to be moving at the site.

 

SUMMARY OF RAPTOR SPECIES SPRING OCCURRENCES, MOUNT LORETTE                            (March 1-April 22. 1993-2016)
species average first occurrence earliest first occurrence average median passage date
TUVU 2 records only: 18 and 31-Mar n/a
OSPR 17-Apr 9-Apr n/a
BAEA 3-Mar 1-Mar 23-Mar
NOHA 4-Apr 24-Mar (3-Mar anomalous) 13-Apr
SSHA 26-Mar 9-Mar (2-Mar anomalous) 16-Apr
COHA 1-Apr 9-Mar 10-Apr
NOGO 12-Mar 1-Mar 30-Mar
BWHA 3 records only: 13, 19 and 24-Apr  n/a
SWHA no records during the count period  n/a
RTHA 22-Mar 9-Mar 9-Apr
FEHA 3 records only: 6, 9, 15-Apr  n/a
RLHA 21-Mar 9-Mar 22-Mar
GOEA 2-Mar 1-Mar 22-Mar
AMKE 16-Apr 7-Apr n/a
MERL 21-Mar 6-Mar 5-Apr
GYRF 26-Mar 12-Mar n/a
PEFA 6-Apr 15-Mar n/a
PRFA 24-Mar 10-Mar n/a

 

 

March 1 [Day 1] (Joel Duncan, assisted by Caroline Lambert) 0930-1700 The temperature was   -6C on arrival and reached a high of -3C for much of the afternoon. Ground winds were SW 5-10 gusting to 19 km/h, and ridge winds were moderate SW. Cloud cover was 80-90% stratus and cumulus with some altocumulus early in the morning. The eastern ridges became 50% obscured in the last hour but were otherwise clear, and the western ridges progressively clouded over from 10% early in the morning to 100% by the end of observation. Light snow fell between 1230 and 1300 and after 1630. Despite the apparently favourable migration conditions the only migrant raptor seen was a subadult Golden Eagle that moved NW along the Fisher Range at 1516. A resident adult Northern Goshawk was seen, and the only other birds recorded were 3 Grey Jays, 1 Black-billed Magpie, 4 Common Ravens and 2 American Dippers. Three visitors came to the site.

7.5 hours (7.5) GOEA 1 (1) TOTAL 1 (1)

Beaver Mines (Peter Sherrington) The Indian Summer persisted into the first week of December and produced the first December record of Peregrine Falcon for the Beaver Mines area on December 4. The rest of the winter, however, was quite brutal with extended periods of cold weather, above average snowfall and many days of high winds to blow the snow around. Above-average numbers (up to 32 a day) of Bald Eagles wintered in the area, but Golden Eagles were quite rare until mid-February when pre-migratory birds started showing up feeding on carrion. Rough-legged Hawks were fairly common except after heavy snow falls when they probably moved east where the prairies were largely snow free and hunting was easier. At least 3 different Gyrfalcons were present in the area and Prairie Falcons were seen regularly when large flocks of Horned Larks and Snow Buntings showed up in January. No Red-tailed Hawks wintered in the area, and only 1 or 2 goshawks were reported all winter. After the early movement of raptors last year I decided to start the count a little earlier this year on February 25.

February 25 [Day 1] (Peter Sherrington) 1100-1500 The temperature was -3C throughout, winds were W-WSW 40-50 gusting to 70 km/h and after cloudless skies to 1230 altocumulus, altostratus and cumulus cloud developed reaching 100% after 1400. A total of 8 adult Golden Eagles glided high to the NNW or NW between 1125 and 1341 providing a very satisfactory start to the season.

4 hours (4) GOEA 8 (8) TOTAL 8 (8)

February 26 [Day 2] (Peter Sherrington) 1200-1430 Not a pleasant day with the temperature dropping from -8C to -9C, winds E-SSE 13-17 gusting 30 and 100% stratus and cumulus giving light snow throughout. Although the Big Hill across the valley was visible no migrants were seen.

2.5 hours (6.5) TOTAL 0 (8)

February 27 [Day 3] (Peter Sherrington) 1200-1600 The temperature was -7C to -5C, winds were SW-WSW 5-15 gusting 35 km/h and cloud cover was 80-100% altostratus, cumulus and altocumulus giving hazy sunshine throughout. The first bird of the day was a juvenile female grey morph Gyrfalcon at 1245 and by 1534 2a Bald Eagles and 12a Golden Eagles had migrated high to the NNW or NW.

4 hours (10.5) BAEA 2 (2), GOEA 12 (20) GYRF 1 (1) TOTAL 15 (23)

February 28 [Day 4] (Peter Sherrington) 1300-1645 Snow that had fallen all morning finally stopped at 1345. The temperature fell from -6C to -8C, winds were calm to light SW, but light E-SE farther east, and cloud cover wasw 100-60% stratus and cumulus that provided hazy sun throughout. The very light winds proved non-conducive for raptor migration and only 1 adult Bald Eagle made slow flapping progress at 1601.

3.75 hours (14.25) BAEA 1 (3)

March 1 [Day 5] (Peter Sherrington) 1000-1815 The temperature was -1C at 1000, fell to -2C at 1400 and rose to a high of 0C at the end of observation. Winds were initially W 15-25 gusting 40 with light snow to 1300 when they became NE-NNW 10-25 during which time the snow became heavier and the ridge was obscured. After 1550 the wind became W-WSW 15-25 gusting 40 km/h, the snow stopped and the ridge cleared. There was a sporadic movement of 2 adult Golden and 1 adult Bald Eagle between 1031 and 1228 which was terminated by the snow. After the ridge at 1649 and unaged Turkey Vulture glided with its characteristic rocking motion to the NW along the ridge, soared briefly then disappeared behind the ridge. This is the earliest ever record of the species, 15 days earlier than the 2 adults seen here on March 16 last year which were, in turn, by far the earliest ever. The vulture was followed by 2 more Bald Eagles (1a and 1j) and the last migrant of the day, a subadult Golden Eagle at 1805.

8.25 hours (22.5) TUVU 1 (1), BAEA 3 (6), GOEA 3 (23) TOTAL 7 (31)

Steeples (Vance Mattson) No observation

 

MOUNT LORETTE SUMMARY COUNT (March 1 to April 22)

 

DAYS 1

HOURS 7.5

 

TURKEY VULTURE (TUVU) 0

OSPREY (OSPR) 0

BALD EAGLE (BAEA) 0

NORTHERN HARRIER (NOHA) 0

SHARP-SHINNED HAWK (SSHA) 0

COOPER’S HAWK (COHA) 0

NORTHERN GOSHAWK (NOGO) 0

Accipiter sp. (UA) 0

BROAD-WINGED HAWK (BWHA) 0

SWAINSON’S HAWK (SWHA) 0

RED-TAILED HAWK (RTHA) 0

FERRUGINOUS HAWK (FEHA) 0

ROUGH-LEGGED HAWK (RLHA) 0

Buteo sp. (UB) 0

GOLDEN EAGLE (GOEA) 1

Eagle sp. (UE) 0

AMERICAN KESTREL (AMKE) 0

MERLIN (MERL) 0

GYRFALCON (GYRF) 0

PEREGRINE FALCON (PEFA) 0

PRAIRIE FALCON (PRFA) 0

Falco sp. (UF) 0

Unidentified Raptor (UU) 0

 

TOTAL 1