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Week 9, 2019: A Sudden Surge

October 3, 2019

Week 9 of our migration monitoring season brought a big surprise as a massive late surge of migrants came through the station during a time when migration is typically winding down. As it turns out, the peak of migration during the 2019 season was actually this week, and not during week 7 and 8 as expected. We banded 548 birds of 24 species which is over four times the average for week 9 and almost three times the previous high for the week. It’s also the second highest of the season, not far behind our record opening week. The week started with two relatively average days before activity picked up on the weekend and peaked with our second and fourth busiest days of the season on Sunday (125 banded) and Monday (133 banded). We actually had four consecutive days in a row with over 100 total captures which is a rare thing for VLBO. We also recaptured 129 birds of 18 species which is the highest recap week total of the season. The weather this week was uncharacteristically cold, gloomy and wet, which probably played a big role in the number of birds stopping at the station. During more typically clear and mild weather in other years, many of these birds are presumably passing overhead without stopping. The sudden onset of cold and snow in the surrounding hills likely triggered many birds to move out.

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Gloomy dynamic skies graces the station this week

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Snow overnight at higher elevations was alarming for birds and people alike!

While numbers were high, species diversity was quite low compared to earlier in the season, though we still tied the record for species banded during week 9 with 24. However, the biggest push came from Audubon’s Warbler (112), Ruby-crowned Kinglet (92), Orange-crowned Warbler (87) and Common Yellowthroat (77). Ruby-crowned Kinglet should actually hold the top spot by far, but the big numbers this week were so unexpected that we unfortunately ran out of the band size that fits this species after banding 50 on Monday. We had to release an additional 91 Ruby-crowned Kinglets unbanded which means their total for the week should be around 180, considering their low recapture rate. This is completely unprecedented as the VLBO season average for this species is only 40! Needless to say, we passed the season record for Ruby-crowned Kinglets on Thursday, then doubled it by Monday and would have tripled it by Wednesday. This also means the banding total for the week should be higher still and would have been the highest of the season if we were able to band all the kinglets netted.
Interestingly, Common Yellowthroat were dwindling at the end of last week when suddenly numbers increased again and culminated with a whopping 34 banded on Wednesday!


Aside from the sheer number of birds, several new species for the season brought highlight moments. The biggest of these was when an American Kestrel got caught in net 4 on Monday! This is a first for VLBO and a big surprise as we don’t even see many kestrels at the station. Other new species for the season were White-throated Sparrow, and Pine Siskin, while a Slate-colored Junco, our 2nd Cassin’s Vireo, 2nd and 3rd Townsend’s Warbler, and 3rd Sharp-shinned Hawk were also highlights.
In addition to the top four species, the migrant waves also brought in good numbers of Marsh Wrens, Song Sparrows, Lincoln’s Sparrows, ‘Myrtle’ Warblers, Wilson’s Warblers, and even a few more Dusky Flycatchers which is quite late in the season.


We also surpassed the milestone of 3000 birds banded this week, concluding with an even 3400. After the first two days of October we’ve already almost surpassed last year’s dismal October total. Who knows how the rest of the month will pan out?

Below are the banding totals:

Week 8 Date
Species Total 26 27 28 29 30 1 2
‘Audubon’s’ Warbler 112 21 5 24 33 18 5 6
Ruby-crowned Kinglet 92 6 4 10 22 50    
Orange-crowned Warbler 87 9 3 4 38 19 9 5
Common Yellowthroat 77 1 3 5 7 14 34 13
Lincoln’s Sparrow 45 2 4 2 2 5 19 11
Song Sparrow 32   7 3 2 7 10 3
Marsh Wren 23   1 1 1 3 13 4
‘Myrtle’ Warbler 21   2 6 9     4
Unidentified Yellow-rumped Warbler 12 1   4 4 2   1
Oregon Junco 10         4 4 2
Wilson’s Warbler 9 1 1   3 1 1 2
Spotted Towhee 5   1     2 2  
Dusky Flycatcher 4 1   1   2    
American Goldfinch 2             2
White-crowned Sparrow 2       1   1  
Pine Siskin 2         2    
Townsend’s Warbler 2       1 1    
White-throated Sparrow 2   1         1
American Kestrel 1         1    
American Robin 1   1          
Black-capped Chickadee 1           1  
Cassin’s Vireo 1         1    
Gray Catbird 1     1        
Red-shafted Flicker 1       1      
Savannah Sparrow 1       1      
Sharp-shinned Hawk 1     1        
Slate-coloured Junco 1         1    
Total 548 42 33 62 125 133 99 54
Species 24 7 11 10 12 15 10 12

 

The recapture totals are as follows:

Week 8 Date
SPECIES Totals 26 27 28 29 30 1 2
Orange-crowned Warbler 38 1 2 1 9 10 9 6
Song Sparrow 18 2 1 2 3 4 4 2
Common Yellowthroat 17 1   1 1 3 4 7
Ruby-crowned Kinglet 14 1 1 2 2 1 2 5
Lincoln’s Sparrow 9   2 1 3 1 1 1
‘Audubon’s’ Warbler 7     1 1 2   3
Wilson’s Warbler 4   2     1   1
Black-capped Chickadee 3   1 1       1
Downy Woodpecker 3 1     1 1    
American Goldfinch 2         1   1
White-crowned Sparrow 2       1 1    
Marsh Wren 2             2
Spotted Towhee 2   1       1  
Unidentified Yellow-rumped Warbler 2       1 1    
American Robin 1         1    
Fox Sparrow 1       1      
Gray Catbird 1           1  
‘Myrtle’ Warbler 1       1      
Oregon Junco 1             1
Red-shafted Flicker 1         1    
Total 129 6 10 9 24 28 22 30
Species 18 5 7 7 9 12 7 11
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Our season totals at the end of Week 9. Red stars indicate record numbers.

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