Saturday, June 18, 2011

Another long awaited return to the wild.


In the late summer and early fall, many species of birds undertake a long distance journey.  These travelers move through our neighborhoods and yards en route to warmer latitudes in which they pass the winter months.  Migration is a challenging time for the birds involved, and the routes they travel are fraught with both natural and human-created dangers.  It is also a roundtrip flight, and those birds that arrive safely on their wintering grounds have but a few months to recover before they must face the dangers again on their return journey in the spring. Invariably during these times of mass movement, the Wildlife Center receives feathered travelers that have succumbed to one of the dangers they encountered.  Migration is an unfortunate time to suffer an injury as, depending on the severity, treatment may require a bird to be in care so long that he or she misses the window for migration entirely.  Such was the case for five migratory birds received by the center in the summer of 2010.

One of the poor birds attacked by a cat. See all his wounds?
Three of the birds we received were Black-headed Grosbeaks.  All three were juvenile birds that were attacked by outdoor housecats.  The first was admitted on July 15, just a few weeks before his migration was to begin.  His body was riddled with punctures and lacerations and he was missing some of his flight feathers and all of his tail feathers.  The second and third grosbeaks came in on August 19 and September 12, and both had various puncture wounds and lacerations from their cat encounters.  All three birds required antibiotics and other treatments that pushed their recovery times well beyond when the rest of their kind had vacated the state. The other two injured travelers were Swainson’s Thrushes.  The first arrived on September 7, and the second on September 21.  Both were admitted with head trauma and other injuries resulting from window collisions.  Like the grosbeaks, the thrushes’ recovery period extended beyond their window for migration.  

Releasing the birds long after their migration period had ended would have created major hardship for them.  They might have become confused and stayed in the area, likely perishing during the winter.  On the other hand, they might have tried to continue on their migration.  Traveling out of season, without the added safety of a flock and having just recovered from life-threatening injuries, they would have been unlikely to survive.  Transporting them south by car or airplane was also a risky option.  Not only would that have been extremely stressful for the birds, it would have required guessing, with a high likelihood of error, where the birds’ migration would have ended and then transporting them across state and international borders to get them to that location. Given the available options, the most responsible choice was to keep the birds in our care until the rest of their kind returned to the state in the spring.  This would allow us to release them in the right place at the right time, and the birds would not be faced with migration until several months after their release.  So, while their fellow flock members continued south to winter in the tropics, the five wayward travelers at the center settled in for what promised to be a very long winter layover.  

And it was a long winter.  In fact, the cold days stretched well into spring; but the birds thrived with a little assistance from the staff in the form of several heat lamps that were strategically placed in their aviary.  While they were no real substitute for the tropical sun, they were clearly welcomed by the grosbeaks and thrushes.  The birds regularly basked under the lamps throughout the winter and early spring as they waited patiently for the warmth of the sun, as well as others of their species, to return to Washington State. In mid-May, Black-headed Grosbeaks and Swainson’s Thrushes came flooding back into the Northwest from their southern wintering grounds, and it was time for those that had been left behind to rejoin them.  As the forested property is a well-used stopover point for migratory birds, the releases took place just outside the aviary door this last week. 


Watching us from the roof right after being released.
The two thrushes that had spent the winter wasted no time dawdling when they were released.  One vanished into the high branches of a Big-leaf Maple tree while the other disappeared into a low tangle of ferns and bushes nearby.  Two of the Black-headed Grosbeaks were released at the same time, and both of them lingered for a short while to get their bearings.  One of them took an interest in the local plant life, nibbling first on the budding leaves of an alder and then those of a nearby maple.  The other grosbeak landed on top of an aviary adjacent to the one that had contained him.  He looked around inspecting his surroundings and the nearby humans who had been his captors.  Eventually both birds disappeared into the forest, returning to the correct place both in time and space. So, what of the third Black-headed Grosbeak? He is still with us hopping around the centers massive grounds.  He is the bird that had lost many of his feathers, and he did not begin to grow new ones until spring arrived and brought with it a hormonal shift.  But they are growing now, and by the time you read this it is very likely that he will have followed his former cage mates back to the world in which he belongs.  When he and the four other survivors begin their long journey south in the fall, I hope that they will arrive at their destination safely, with no repeat of the trauma that brought them to the Wildlife Center.  You can assist them in their migration by doing your part to keep them safe from cats, windows and other human-created dangers they may encounter along the way.     
after being released one sampled the local vegetation.

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