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Thursday, March 19, 2015

Tracking bird migration by radar


An accidental but very useful tool in keeping track of bird migrations into and through Texas is NexRad;  ”next generation radar”. NexRad is blind to non-moving objects (like buildings, towers and a mass of birds sitting on trees in a forest). Nor does it pick up very low objects (insects, dust, smoke, and most local birds). To be visible on radar, bird flights must be above roughly 350 feet. This covers migratory flight very well.

    An increasing number of TV stations are doing this during the spring migration.
     In general birds flying over the Gulf (where almost all mass migration takes place) fly at several thousand feet above the water. Birds migrating over land fly lower (1000 ft. or less). Storms or unseasonable cold sometimes mean that migrating birds aim for land sooner than normal (hitting Corpus Christi rather than Galveston for example) so they can stop and rest. Still, many migrating birds perish over the open waters.


 

 

 

 

OWEN YOST, in addition to being a blogger, is a licensed Landscape Architect emeritus who has lived and worked in north Texas for over 30 years. He is the recipient of a Lifetime Achievement Award of the Native Plant Society of Texas, and is a member of the American Society of Landscape Architects (ASLA), International Federation of Landscape Architects, National Wildlife Federation and the Audubon Society. His office is at Yost87@charter.net in Denton.

 

 

Sunday, March 15, 2015

So you want to attract Purple Martins to your yard or neighborhood...


 
Purple Martin
Around now is when Purple Martins start to settle in the north Texas area. The “scouts” come first, followed by hordes of others. If you’ve put out the “welcome mat”, they may just settle down at your place.

         They prefer nest sites cleaned of the majority of old debris, near water, and free of other birds (especially House Sparrows). Martin houses are almost always on tall, metal poles, and can be raised and lowered easily for regular maintenance. Since their natural habitat has mostly disappeared, they are dependant on humans for nesting sites, so the house typically comes in a box.  In Texas, Martin houses should be made of a material that withstands heat, and be white to reflect our sun (both are crucial here). The houses need to be cleared of old nests at least yearly, and you’ll need to monitor it so other birds don’t take it over. If a house doesn’t come with a pole, shop elsewhere; and make sure the pole is easily raised and lowered.

    Purple Martins are exceptionally good fliers  – all their food is caught during flight (the ultimate “in-flight meal”). They’ve been timed at 41 mph. It’s not unusual to see hundreds of them at once; on, in and around the special house you provide. 

Each year more and more people put up Martin houses; either the traditional “apartment house” or the natural-looking gourds. Also, several neighborhoods and communities in north Texas have become Purple Martin landlords, and enjoy a reduction in flying insects.

 

 


Screech Owl
Where are owls’ ears?      Despite how they appear, owls do not have external ears; 100% of their hearing function is inside the body. What look like ears on their heads are just tufts of feathers mostly unrelated to their exceptional sense of hearing.  What is also exceptional is their eyes, which let them see in near-total darkness.

 

 

OWEN YOST, in addition to being a blogger, is a licensed Landscape Architect emeritus who has lived and worked in north Texas for over 30 years. He is the recipient of a Lifetime Achievement Award of the Native Plant Society of Texas, and is a member of the American Society of Landscape Architects (ASLA), International Federation of Landscape Architects, National Wildlife Federation and the Audubon Society. His office is at Yost87@charter.net in Denton.