Scavengers

Where there are large flocks of birds crowding together, there are usually a few fatalities, either from fighting with each other, or from predators.  And where there are carcasses, there are usually vultures, waiting…

What an advertisement for the wildlife refuge at Los Pantanos de Villa in Lima.

Dead palms make excellent perches for scouting out carrion, or for early morning basking.

And they don’t seem to care if you walk right up to them, like this Black Vulture perched on a dead palm.  Dirty feathers are typical of vultures that roost communally and poop on each other overnight.

Turkey Vultures perched near the congregations of Gulls, Terns, and Skimmers in the large lagoon.

Just hanging out, waiting…

There were quite a few dead Gulls and a couple of Snowy Egrets lying on the beach. Some had been picked clean, others looked fresh.

Scavengers, like the vultures, perform essential clean-up, leaving nothing but skeleton and feathers when they have finished with a carcass.

Vultures on the beach

Taking a lesson from the Oroville dam almost-catastrophe, water levels in the Vasona reservoir south of San Jose, CA, have been lowered substantially prior to the next series of storms expected this weekend.

The water in Vasona Reservoir is quite muddy, with a high volume coming in from highly eroded banks upstream.  The lake level is low enough now to expose some minor gravel islands, though.

Apparently, fish stranded in some of the back channels of the reservoir became fodder for the local bird life.  Turkey Vultures, seagulls, crows, and even a rarely seen Bald Eagle have been spotted feeding on the fish carcasses the past couple of days.

A “venue of Vultures” (I.e., a group of them) were still present picking over the last remains of a few fish this morning.

Turkey Vultures:  where you see one, you usually find many

The weather wasn’t chilly, but when the sun emerged from behind some low clouds, the Vultures immediately began basking, backs to the sun and spreading their wings wide.  First one, then another and another…

Does one Turkey Vulture copy another?  Coordinated basking behavior…

Turkey Vulture show-off  — “I’m so pretty, oh, so pretty…”

Turkey Vulture taking off.  If you can ignore the naked red head, they are kind of pretty, especially those long, black and white wings.

Raptor feast

Nothing attracts raptors, especially scavengers like vultures and Caracaras, like free food.  Within just a few minutes of spreading a banquet of frozen chicken on the ground in front of our blind at Laguna Seca near Edinburg, Texas, the Turkey Vultures and Black Vultures began circling overhead, and a couple of Caracaras made swooping passes over the carcasses.  Finally, they decided to test the meat.

An adult (left) and juvenile Caracara were the first ones to sample the banquet.

Using their feet to hold the meat, Caracaras grab chunks of flesh or skin and tug on it until it rips free.  They might immediately swallow big chunks but often fly off to a safer location where they can eat without competition from other birds.

Juvenile Caracara flying off with a meal

Turkey Vultures were more timid about approaching the meat.  They usually wait until Caracaras have opened up the carcass before they start to feed.

A Harris Hawk took a look at the Caracara feeding frenzy and decided to join in.

The Harris Hawk warned off an encroaching young Caracara several times, smacking it with its wings or threatening with its beak.

A juvenile White-tailed Hawk landed on the feast table but must not have liked what it saw and took off. It’s a much larger bird and could have dominated the other species there for a free meal.

Even though Black Vultures are larger than both Turkey Vultures and Caracaras, they didn’t try to dominate either of the other species. Two Black Vultures instead fed on the fringes of the crowd.

Competition for food inevitably leads to some conflicts between individuals.  Exactly what determines who gets to eat what and when may be influenced by the number of individuals of a particular species present, their size, age, and/or temperament.

In this mixed group of raptors species, the smaller Caracaras clearly had the edge, probably because of their numbers, although age didn’t seem to matter, with those aggressive juveniles badgering the adults for food.  Both Vultures species were lower on the pecking order, despite their larger size, and took a backseat to both the Harris Hawk and the Caracaras.  However, they stuck around to clean up the scraps after others had left the feeding area.

After two hours of intense feeding, there was nothing left but tiny scraps for the mammalian scavengers to clean up.

Basking tree

The trunk and top branches of the Buckeye tree outside my (somewhat dirty) porch windows are brightly illuminated with the morning sun, making it the perfect place to bask in whatever heat the sunlight can provide on this chilly morning.

A chilly start…

Early in the morning, I’ve noticed a variety of birds and squirrels using the buckeye as a basking spot.

You don’t normally see White-breasted Nuthatches at rest in this posture (head up). Notice how the bird is plastered right up next to the trunk of the tree with its feathers maximally fluffed. Is it possible that the tree surface is actually “warm”? (well, probably warmer than the air…)

Red-bellied Woodpeckers apparently like the buckeye as a basking spot as well.  This bird was sitting at rest, not foraging in this spot.

Even the much larger-bodied Gray Squirrels enjoy a little basking time on the trunk of the tree when the temperatures dip into the -20 F range. Belly and tail are plastered tightly to the trunk of the tree to soak up whatever warmth it can provide.

Usually we associate basking behavior with reptilian thermoregulation — sun-loving turtles and lizards, for example.  Even crocodilians lie around in the sun letting its heat warm them while they digest their latest meal.  But basking becomes important to birds and mammals as a means of economizing on the high metabolic expense of staying warm in extreme cold.

Here’s a bird that specializes in basking to warm up on cool mornings.