Montana CBC results 2019-20

Compiled by Rosemary H. Leach

Total individuals

Montana’s CBC season had somewhat favorable viewing conditions and we tallied 233,758 individual birds from 33 circles.  Total birds was higher than the average of the past 5 years (CBC #115-119, nearly 219,650 birds), an increase of around 14,110 birds.  Total birds this year was around 9,500 fewer than the most recent high tally (CBC #115, 243,285 birds from 32 circles).  This metric is not readily available for years prior to #115.  One circle (Cut Bank) was not able to run this year, due to bad weather on count day. 

Total Species

We totaled a cumulative 141 species on count day and 4 more during count week (CW, Snowy Owl, Great Gray Owl, Ruby-crowned Kinglet, and Brown Thrasher [from Helena, with photos in eBird; 4 previous CBC records for the state (Marks et.al 2016, p 441)].  Total species was near to the average from the past 5 years (#115-#119—143 species). 

Cumulative list increased by 2 species

Two species were added to the cumulative state listWestern Tanager (Bozeman, Photo 1, formerly a CW bird from Hamilton) and Chukar.  While Chukars have been reported fairly consistently at the Clark Canyon circle since CBC #97, the species was not considered established in that area until 2019 (Montana Bird Records Committee 2019 minutes).  The only other area of the state where the species is considered established (Pryor Mountains south of Billings) does not have a CBC circle.  Thus, Chukar can now contribute to our cumulative species total—now at 221 species.

Participation

A total of 777 field participants logged 1,436 party-hours and 8,117 party-miles, all a bit fewer than last year, but slightly higher than the average from the past 5 years (CBC 115-119, all less than a 9 % increase).  We had 163 feeder-watchers, which was about 20 more than last year and an 8 % increase from the average of the past 5 years (#115-#119).  Feeder watchers tallied 429 hours, which was about 76 hours more than last year, and a 26% increase from the average of the past 5 years.  Increased effort may help explain the higher numbers of individual birds seen this year. Again, Missoula had the most participants (108, 89 field and 18 feeder-watchers) and Little Rocky Mountains had the fewest (1).  Bigfork continues its streak with the most species (92), followed by Missoula (82) and Stevensville (76).  We have yet to break 100 species on a single circle—the closest was 98, also at Bigfork (CBC #118), but I predict it could happen in the next 5 years, with combinations of luck, skill, abundant open water, and favorable field and viewing conditions.

 High totals for the 6 most abundant species

Total individual birds observed here have fluctuated mostly with the number of Canada Geese (near 89,100 this year from 28 circles) and Mallards (near 25,540 from 29 circles), our 2 most numerous species since #115.  Goose number have steadily risen since about CBC #95.  Mallard numbers have ranged from about 25,000 to 45,000 since about CBC #91.

Next most numerous was Bohemian Waxwing (15,187) followed by European Starling (11,269).  These each can vary widely, but the magnitude of yearly variation has been greater for Bohemian Waxwings than for starlings.  Some consecutive years can vary by nearly 24,000 individuals of this waxwing species (!), reflected in the graph of birds per party-hour by year, Figure 1  Using the metric of birds-party hour is a way to compare numbers of birds detected across years, because the numbers of individual birds are adjusted by factoring in effort for each year. 

Figure 1. Variation in Bohemian Waxwing numbers, as measured by birds per party-hour, Montana Christmas Bird Count Years #9 (year of first detection) – #116 (note: could not access chart beyond these years).  

The only other species over 10,000 individuals were House Sparrow (13,747 from 27 circles), and Rock Pigeon (10,236 from 27 circles).  House Sparrow numbers and birds per party-hour have remained relative stable since around CBC #85, but the number of birds per party-hour have been much lower compared to the period from about CBC #75 and earlier.  Rock Pigeon numbers per party-hour have been relative stable since around CBC #95 thru #120.

 Doves

Mourning Dove totals (404 from 13 circles) were lower than recent years, but not the lowest on record.  For perspective, birds per party-hour this year (0.28) was generally near or higher than during the period from CBC # 100 (0.33) and earlier, or the flat part of the graph in the early portion of Figure 2.  Note, I could not print this graph with this year’s data point, so I have added the point in the text box on the right side of the figure.

Figure 2.  Mourning Dove birds per party-hour, Montana CBCs #48 (year of first detection) –#120.

It is worth noting that Mourning Dove birds per party-hour were fairly high during the period when Eurasian Collared-Doves were increasing (about CBC #105 and forward, see the peaks seen in Figure 2).  These peaks may argue against the notion of displacement of Mourning Doves by Eurasian Collared-Doves (more on that below). 

This year, total Eurasian Collared-Doves (4,815 from 26 circles) was lower than last year (5,821 from 28 circles).  The numbers for birds per party-hour for Eurasian Collared-Dove (Figure 3) are only available in graph form from CBC #1 through CBC #115.  That is, the most recent points are not available in a cumulative graph, due to downloading glitches at the Audubon CBC website.  However, figuring birds per party-hour by simple division for CBC #114-120 (Figure 4) shows a decrease, then and increase and finally a decrease in CBC #120, to near #113 and #114 levels.

Figure 3.  Eurasian Collared-Dove birds per party-hour, Montana CBCs #101 (year first detected)—#115 (note: a more recent cumulative graph is not currently available from National Audubon, see their CBC Historical Results by Species).

Figure 4.  Eurasian Collared-Dove birds per party-hour detected during Montana CBCs #114-120

Perhaps the downward trend from CBC #117-#120 of Eurasian Collared-Dove birds per party-hour will continue, or it will level off, only time will tell. 

Most widespread species

This year, the Common Raven was the most widespread species (on 32 of 33 count circles, total 3,412 individuals).  The species was missing from the Miles City count, where it has been recorded from 5 of 38 count years from CBC #77-#119.  Black-billed Magpie almost tied with Common Raven, found on 31 circles on count day (with a total 6,562 individuals) and also 1 CW site, so 32 circles were represented.  Magpies were missing from Glacier National Park, where the species has been recorded on 35 of 44 counts, including 4 CW records, from CBC #74-#119.  Both corvids overtook Bald Eagle, which had been the most widespread species since CBC #115.  Bald Eagle numbers have ranged from just over 800 to just over 1,000 birds (last year) during the period CBC #111- #120.  This year, Bald Eagle occurred on 31 counts (976 birds) followed by Black-capped Chickadee (on 30 counts with 5,421 individuals).  All other species were found on fewer than 30 circles, including any CW records for each.

Rare Birds

Rare (reported from 6 or fewer CBCs) species found this year, other than the Western Tanager and Brown Thrasher discussed above, included 2 Green-tailed Towhees found on the Yellowstone National Park count, with photos (Photo 2). Single birds have been found on CBC #91 at Park County, #103, also at Yellowstone National Park, and #116 at Ennis.  In addition, a male Black-headed Grosbeak with convincing details was found at Bozeman this year (tallied previously on CBC #84 at Great Falls and #92 at Libby).  Counters—please be aware that Rose-breasted Grosbeaks are essentially just as likely as are Black-headed Grosbeaks on our counts, so be sure to note breast color and streaking in similar-looking females or immature Purple finches.  Lesser Goldfinches (5 at Hamilton this year) have been reported from 3 previous counts—5 birds again at Hamilton and 2 birds at Three Forks, both during CBC#119, and 1 bird at Missoula (CBC #113).  The species has become fairly regular year-round in both Ravalli and Missoula counties during the last 5 years or so, but because the identification can be confusing for less experienced birders, we still track its occurrence closely.

Other species of interest

Ruby-crowned Kinglet was a CW only bird this year (from Missoula), and although it is not easily found during winter, it has been reported state-wide in low numbers (average 4) since the early 70s.  This suggests our crews know what portions of their circles to scour for the species during count week. 

Blue Jays were found on 25 counts and 2 CW sites this year, and totaled 482 birds.  Their numbers have steadily increased since they were first recorded—as a CW bird on CBC # 74.  From then through this year, they have been detected on 45 counts.  This year’s number was 4 times that of the average found during the last 7 years (CBC #113-119, average of 120) as well as nearly 4 times the average of the last 7 years of birds per party-hours (ave =0.09, this year = 0.34).

Greater Sage-Grouse, a state species of concern, was found on 1 count (Big Hole), with a total of 8 birds.  I calculated birds per party-hour for this year (0.005), and although I have no way to add it to Figure 5, I can see that it equals the CBC #110 point, which is located almost on the 0 line—just above and to the right of the ‘9’ in year ‘109’.  This point is considerably lower than the 5 high points (near 0.1) since the 50s, and orders of magnitude lower than the highest point of 11 birds and 0.3 birds per party-hour that was recorded during their first detection on CBC #40 (Figure 5). 

Figure 5.  Greater Sage-Grouse, birds per party hour, CBC # 40 (year first detected)—#119, The last data point is CBC #117, 0.02), because no birds were detected during CBC #118-119. (Note-could not down-load a more recent cumulative graph for this species).

Notice too how many other points are near to 0—as this year’s number is—in Figure 5.  Keep in mind that the graph only includes counts where the birds were actually detected, and there were no CW only birds in the data set.  This suggests that finding Greater Sage-Grouse on Christmas Bird Counts is a challenge, and has been—with a few exceptions—for most counts since the 80s, since most counts are not located in areas where Greater Sage-Grouse winter and access to these locations can be challenging.  We hope that our cooperative conservation plans for the species—worked out with all of our partners and stakeholders—remain in place in the future, to address concerning low population data for this bird.

Night Effort and Owl Detections

This year some hearty counters contributed to a cumulative total of 10.95 night-time partyhours and 32.7 cumulative night-time miles, to detect 9 of our 13 potential winter owl species (7 species encountered on a count day, and 2 CW species).  We missed Eastern-Screech, Northern Hawk-Owl, Boreal, and Barn Owl.  (We would not expect Flammulated or Burrowing Owls on a CBC.)

Our totals included a whopping 120 Great Horned Owls (23 from Stevensville, 20 from Missoula, and 19 from Ruby Valley alone)!  This was the 3rd year (also #113, #118) to count or exceed 120 Great Horned Owls.  Other owls found, besides the 2 CW species tallied (Snowy at Chester and Great Gray at Bigfork) include Western-Screech Owl (1 at Missoula); Northern Pygmy-Owl (6 birds from 4 circles, plus 2 CW circles); Barred Owl (1 at Missoula and a CW tally at Kalispell); 30 Long-eared Owls from 4 circles (25 from Missoula, which includes a long-term study area); Short-eared Owl (34 from 4 circles and 26 alone from Three Forks! and 1 CW circle); and finally 2 Northern Saw-whet Owls 1 each from 2 circles, and 1 CW tally. 

Falcons

Participants found all possible wintering falcons this year, with 3 Gyrfalcons (1 each from 3 counts, not including 1 CW record), 4 Peregrines (our least likely winter falcon) from 4 counts, 40 Prairie Falcons from 19 circles (plus 1 CW record), 46 Merlins from 14 circles, and 69 American Kestrels from 13 circles (plus 1 CW record).

Hawks

Participants found 1,012 Red-tailed Hawks from 24 circles (plus 2 CW records), and an additional 29 Harlan’s-type Red-tails (from 8 counts, all of which tallied non-Harlan’s red-tails as well).  Rough-legged Hawks totaled 830 from 27 circles.  Counts that found Rough-legged and no Red-tailed Hawks of any type included Chester, Little Rocky Mountains, and McNeil Slough.  Counts with neither red-tails nor rough-legs were West Yellowstone, Yellowstone National Park, Glacier National Park, and Upper Swan Valley.  In contrast, Ninepipe National Refuge tallied 248 Red-tailed Hawks, 11 Harlan’s Red-tailed Hawks, and 113 Rough Legged Hawks.  Clearly, attention to conservation of habitats such as prairie, grassland, and agricultural fields—habitats dominating the Ninepipe site and generally not protected by National Parks—are important for maintaining our suite of wintering raptors species. 

Gulls

Expected gull species found included Ring-billed, California, Herring, and Glaucous Gull.  Less frequently encountered included Mew Gull (1 from Bigfork), Lesser Black-backed Gull (1 from Fort Peck, 1 CW from Flathead), and Thayer’s (now considered Iceland—3 from Fort Peck, and 1 each from Kalispell and Bigfork).  We all are on alert for a future possible Slaty-backed Gull, time will tell.

Thanks to all of the field and feeder participants, and circle compilers.  We could not have accomplished this work or any meaningful analysis without your efforts.

Rosemary H. Leach
Missoula, MT

Photo 1.  Western Tanager.  Count day photo, 14 Dec 2019, Bozeman Count, Robin Wolcott photo, bird was observed through 19 Jan 2020. 

Photo 2.  Green-tailed Towhees, recorded throughout Dec, and photographed 12 Dec 2019 (before count day of 22 Dec 2019), at the same site (Gardiner, Montana) as count day, Yellowstone National Park, Howard Weinburg photo.


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