STORIES from the Seeley Lake Banding Station

American Robin # 120237102
The secret of how birds warm their eggs

This female American Robin was first captured on June 14, 2001 as an adult and  was then recaptured once each summer.  In all five summers, this female had a brood patch, which is used to incubate eggs.  Brood patches develop on most female birds (and males in some species) when they loose their belly feathers and extra blood vessels develop on the belly to bring hot blood and fluid to the surface of the skin.  When the female sits on her nest she presses her brood patch against the eggs, and this fluid-filled patch heats the eggs quickly and evenly. 

The average clutch size for American Robins is 4 eggs, and Robins regularly rear 2 broods of young each summer.  So if this female has been successful at rearing just one brood per summer for the past 5 summers, she may have helped 20 of her young fledge their nest! 

The majority of American Robins in Montana are most likely short distance migrants that winter in the southern US and northern Mexico.

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Black-capped Chickadee # 225021686
A life-long Seeley Lake resident

This male Black-capped Chickadee was first captured on July 14, 2001 as a “hatch-year” or juvenile bird born that summer.  Juvenile birds of many species disperse from their natal territories later in the summer, but chickadees appear to disperse relatively short distances (~200m) two to four weeks after leaving the nest. 

Song Sparrow # 154198212
A lesson on estimating annual survival

This male Song Sparrow was first captured on June 14, 2001 as an adult bird, was recaptured once in 2002, but then not seen again until 2005.  Unfortunately, there is no way to know whether he was present and breeding at Seeley Lake in 2003 and 2004 and we simply missed him, or whether he decided to breed elsewhere for a few years.  Regardless, this gap in the recapture history highlights the weakness of using banding records to estimate annual survival: in every case you can only measure apparent survival, because when you fail to recapture an individual this may be due to death, emigration, or the fact that the bird present but we simply failed to capture the bird. 

Song Sparrows in Montana are most likely either altitudinal migrants that move from the mountains to the valley bottoms for the winter or short distance migrants that move as far south as northern Mexico.  These hardy birds return to their breeding territories as early as March, and at our station we have banded fledglings as early as mid June in 3 of 5 years.  This means that Song Sparrows are initiating nests at Seeley Lake by the 3rd week of May, if not earlier. 

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American Redstart # 223007303
A beautiful bird that can really put on the fat:
This male American Redstart was among the first few birds captured on our first day of bird banding at Seeley Lake - June 2, 2001.  This bird’s jet-black plumage immediately identified him as an “after second year” bird, at least 3 years old.  We have now recaptured him 9 times - at least once every summer except in 2003 - and when we last captured him in 2005, he was at least 7 years old. 

Birds’ weights fluctuate throughout the year depending on whether they are expending energy to feed young or depositing fat for migration.  On July 14, 2001 this Redstart weighed 8 grams (less than 3 pennies!) and when we recaptured him again on July 24 he weighed in at 10 grams, so in just 10 days he had gained 25% of his body weight!  It’s likely that he was beginning to deposit fat in preparation for a long flight south for the winter.  Large numbers of American Redstarts spend the winter in Western Mexico and the Caribbean Islands (a distance of ~3000 miles to the Lesser Antilles) but they also winter throughout Central America and as far south as northern South America.

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Swainson’s Thrush # 154198208
A true frequent flier:
This female Swainson’s Thrush was first captured on June 2, 2001 as an “after second year” bird- so she was at least 3 years old.  We recaptured her later in the summer of 2001 but then we didn’t see her again until the summers of 2004 and 2005, at which point she was at least 7 years old.  In all three summers, this female had a brood patch that she used to incubate her eggs. 

Swainson’s Thrushes winter primarily in southern Mexico and northern South America, including Venezuela, Columbia, Ecuador, and Peru.  If this bird winters in central Columbia, this is a distance of approximately 4000 miles from Seeley Lake, Montana; if this bird is at least 7 years old, then she has made the 8000 mile round-trip journey at least 6 times, for a total of 48,000 miles - how’s that for racking up the frequent flier miles! 

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Northern Waterthrush # 155140417
A faithful summer visitor to Seeley Lake
We first captured this male Northern Waterthrush on June 14, 2001 as an adult.  He has since become one of our most regular recaptures as we have recaptured him at least once every summer through 2005, at which point he was at least 6 years old.  Relatively little is known about the proportion of birds that return to the same breeding site year after year, but banding records like the one we have for this males indicate that at least some individuals are extremely site faithful.