Swainson's Hawks, NE San
Antonio: Nesting 2006, 2007, 2008, 2009
a summary of key dates
and facts, click here.
2006 videos of the
These are not too good
2007 videos of the
These are better
2008 videos of the
birds are here.
2009 videos: none yet
2006 Photos of the birds are here.
2007 Photos of
the birds are here.
2008 Photos of
the birds are here.
2009 Photos of the birds are
2006 Daily observation log is here.(April
2007 Daily Observation log is
here.(late February to early October)
2008 Daily Observation log is here.
(late March through 7/24)(remaining obs. not entered yet)
2009 Daily Observation log is
here (late March through present)
April through June, the remainder is on the summary page link above
By 4/4/2006, a pair of Swainson's Hawks had
portion of NE San Antonio to set up a territory.
Their chosen territory,
based on observations through the
spring and summer 2006 is shown here. The entire territory is
commercial. In the view, the end of the runway can be seen in the
NW corner of the image, while Salado Creek can be seen to the east and
outside the territory. The red dashed diagonal street is
Nacagdoches while the big solid red street is Loop 410.
During all of April the pair soared continuously in this territory,
often climbing to 1000' and diving back but never landing except at one
place. That place was the south facing corner of the roof of the
Gauranty Bank building near the corner of Nacagdoches and Loop 410.
Pair on the roof, as seen from inside
chase bank building.
Female on the roof, as seen from
Garanty bank parking lot.
Typical soaring here, as seen from
By mid-April they spent their time equally between soaring up high,
perching on the south-facing roof of the Gauranty Bank building, and
swooping around the canopy trees in the northern third of their
This picture shows an color infrared
air photo of their residential
territory. This image shows the residential nature of the
territory very well. During early May the birds became harder to
they ceased to soar. They were building a nest Near the frost
Bank building. They could still be seen occasionally gliding and
weaving among the canopy trees south of the Frost Bank building.
Here is an air photo of the
nest sites for 2006, 2007, and 2008 in the closed canopy
location. Note they chose the densest tree
area within the neighborhood. The nest sites were so dense that
nests cannot be seen from the cul-de-sac by the nest or from the office
buildings above the canopy. Frost Bank parking garage, Loop 410,
Nacagdoches, and a few other buildings are labeled in yellow.
What was probably
2005 nest in the
closed canopy, about 50 feet west of the 2006 nest. This nest was
refurbished and used in 2008(seen
In 2006, Between May 10th and May 15th the female began incubating and
remaining adult could be seen flying, usually low between the
trees hunting food. Much of the male's time was spent perching and
A favorite hunting perch was this
cottonwood tree in the vacant
lot adjoining the Frost bank.
From late May through June the male brought food to the
This food was of at least three components; small rodents the size of
voles or large mice, baby birds, mostly grackles, and something
smaller, perhaps cicadas. Most of the food was baby birds.
By mid-June the male began soaring again but still hunted for food to
bring to the nest. often the male would not return immediately to
the nest with food but would soar around while holding the prey in one
talon. Once in a while the bird would drop the prey from a great
height and plunge to retrieve it a couple of times, before gliding back
down to the nest.
The male seems to bring food to the nest about once per hour.
During June 2006, I noticed it took the male about a half hour to find
food. The male, by late June alternated his hunting between
perching at low vantage points and gliding among the canopy
trees. The male has at least 4 places within the neighborhood he
will land and watch for prey.
The remainder of the
male's time during June was spent soaring up close to the clouds
and among the departing jet planes, or perched on the roof of the
This seems to be a near identical repeat of 2006. The 2007
nest is about 25 yards south of the 2006 nest. The pair raised 1
fledgling. Near the end of the season the pair did spectacular
food drops to the juvenile who intercepted the prey in mid-drop.
This was after wedging prey in tree crotches, forcing him to clamber
about too get it, sometimes in an adjacent tree.
The male arrived first, the female about a week later. A nest
in the same area was refurbished by April 28th. This nest had
been used last around 2005. The male apparently
contributed to the refurbishing since he was in it stomping around
female was watching from a block away. Incubation started 5/2/08.
Two very active white chicks were visible in the nest on 6/18/08.
The three chicks were grown and all left the nest tree on 7/22/08, a
week earlier than the two previous seasons.
Again, the male arrived first, followed by the female several days
later. Female arrived missing two primary feathers, not typical
but otherwise healthy.