After 5 years, something ate my fish.....

......came home from work the other morning and 4 adult shubunkins had
disappeared. No trace of them on the perimeter of the inground fiberglass
pool or on the bottom. Two days later, the other 3 adults are gone. Only
survivors - a 5 year old koi (huge) and 4 shubunkin yearlings hiding like
scared rabbits around the pots on the bottom.

The little pond is 30" deep with almost vertical sides, partially covered by
a Japanese maple tree, and set right against my house and patio. Five years
of flawless operation brought to a halt. I am in no rush to replace the
fish just yet since I figure I am now feeding some long-legged bird in the
neighborhood.

My question.....what breed of bird in the Dallas / Ft. Worth area of Texas
is the likely culprit? There is a small city lake stocked with fish less
than a half-mile from my house which may be the main source of
attraction....

Thanks for any help.

Jay