Sergio Alvarez had been fishing with no luck before he turned his sights on a pelican. Alvarez was presumably going to eat the bird, but witnesses contacted the police before he had a chance.
With all due respect to the pelican, this seems less a case of animal cruelty and more a circle of life sort of thing. Pelican eats fish. Man eats pelican. It's unconventional, but it's not outside the realm of comprehension.
On the other hand, strangling a pelican does sound awful — especially because those long, vulnerable necks seem like a real evolutionary disadvantage.