Saturday, April 10, 2010

Three Weeks and Counting Down

Although Sibley's Guide to Bird Life and Behavior fails to note the incubation period for Burrowing Owl eggs specifically, the guide and my most recent observations seem to indicate that there may be fledglings at the burrows within a few weeks.

The Burrowing Owl above was photographed at Cape Coral Library in April 2010.

Sibley notes smaller owls to have the shorter incubation period while the largest owls have incubation periods of up to five weeks.

I was able to make four trips to Cape Coral to observe the Burrowing Owl since my last post and also made a trip to Harns Marsh Preserve in Lehigh Acres.

The Burrowing Owl above was photographed at Cape Coral Library in April 2010.

My speculation of the timing for the hatching of the owls is based on what appears to be strong evidence.

Every single burrow observed along a residential street parallel to Skyline Boulevard south of the Cape Coral Library had a sole owl at the entrance to the burrow on the evening of 8 April 2010.

The Burrowing Owl above was photographed at Cape Coral Library in April 2010.

Just days before, in most cases, both owls were observed at the burrows so there's the possibility that the females have most recently been in the burrows laying and incubating eggs.

My research of the Burrowing Owl has led to the understanding that owls will typically lay one egg every day or two in favorable conditions of food availability (thus far I have only observed food consumption on two occasions) and lay up to five eggs.

The Burrowing Owl above was photographed near Cape Coral Library in April 2010.

I've found the Burrowing Owl sex to be extremely difficult to distinguish as the bird's appearance is so similar.

There was a pair of owls I observed on Wednesday at the Cape Coral Library where one of the bird's breast was significantly whiter than the other.

The Burrowing Owl above was photographed near Cape Coral Library in April 2010.

The birds mated and, with a close look at the photographs taken, I will be able to determine which of the two was making enhancements to the burrow by digging at its entrance which I observed for the first time.

I am quite confidant to note in my study of the Burrowing Owl that the male stays at the entrance of the burrow while the female will sometimes leave it briefly prior to sunset.

The Burrowing Owl above was photographed near Cape Coral Library in April 2010.

Under such occasions where the female leaves the burrow entrance, she most often returns at the bequest of the male with his call where mating has often been observed immediately thereafter.

There is a burrow south of the Cape Coral Library that still does not have the PVC pipe installed to indicate its presence.

The Burrowing Owl above was photographed near Cape Coral Library in April 2010.

While I considered immediately reporting the burrow and its owl activity when found, I am glad now in hindsight that I had not.

A story has been told to me by my work acquaintance Stephanie Sikora that Burrowing Owls that were active at a Publix Super Market on Cape Coral Boulevard abandoned the burrow when protective measures were put in place.

The Burrowing Owl above was photographed at Cape Coral Library in April 2010.

Although I've spent quite a few hours observing the owls at this particular burrow south of the library, I have not observed them to mate which I cannot explain more than unusual.

There were several mating events again observed in lighting conditions too dark to photograph.

The Burrowing Owl above was photographed near Cape Coral Library in April 2010.

This past week also offered me the opportunity to photograph the Swallow-tailed Kite for the first time at Harns Marsh Preserve.

While I had observed the kite in the area of the Southwest Florida International Airport on several occasions late last fall and most recently this past week as well, I didn't have my camera with me.

The Burrowing Owl activity above was photographed at Cape Coral Library in April 2010.

There were numerous waterfowl at close range at Harns Marsh Preserve including several species.

A highlight in their sighting was the Common Moorhen which involved a chase as I've observed once before at Green Cay Wetlands and Nature Center near Delray Beach.

The Common Moorhen above was photographed at Harns Marsh Preserve in April 2010.

Although I didn't see the Snail Kite at Harns Marsh on this week's visit, it was reported to have been observed that morning by a fellow visitor and world travel I met named Hemant Kishan.

I also met other interesting people including the mother (recovering from a broken ankle yet insisting on walking a great distance at Harns Marsh Preserve) of the Chairman of the Wildlife, Ecology and Conservation department, John P. Hayes, at the University of Florida.

The wildlife enthusiasts above were photographed at Harns Marsh Preserve in April 2010.

I encountered Cheryl, Gloria and Wes as well visiting from Venice, Florida, where I was told of some extraordinary bird activity and recovery around the Venice Rookery.

Linda from Michigan was also a pleasure to speak with as she told me of a seasonal wildlife photographer that has studied the Scarlet Ibis with great success and most recently reported to have been observed at Little Estero Island Lagoon.

The wildlife enthusiasts above were photographed at Harns Marsh Preserve in April 2010.

Certainly off the subject of wildlife though in fitting with the title of this blog entry, I want to note that I witnessed the launch of the Space Shuttle Discovery on the morning of 5 April 2010 from Fort Myers.

It was quite extraordinary as the light from the shuttle's engines was comparable to the brightest anti-collision lights of large commercial aircraft flying overhead at night toward the above mentioned airport.

The Swallow-tailed Kite above was photographed at Harns Marsh Preserve in April 2010.

Although I didn't photograph this event, it will always be a fond memory, and may be seen as witnessed in close proximity to Cape Canaveral by pbaser and blogger Tim Rucci.

1 comment:

  1. I am not a biologist but rather an avid Burrowing Owl observer and advocate. This year (2010) the owls are a little later in producing young here in Cape Coral. The extremely cold winter may have had something to do with this. To date, (April 11, 2010) there have been no reports of juveniles as yet, and last year at this time there were numerous juveniles reported.
    You are correct in your suggestion that juveniles will be appearing soon. There have been signs of nest decoration for several weeks now.
    The incubation period is 28 days for these owls and you are indeed correct in your statement that the eggs hatch on different days. This accounts for the observation that within a single brood, it is very obvious that there are differences is sizes between the juveniles as they grow so fast.
    While broods of up to 5 are common, the pair that are nesting on my front lawn had 7 one year and I have seen a photo of the western species with 9 juveniles.
    On a final note, often the only way to tell the female owls from the male owls is coloration. The males tend to be lighter in color and the females darker. This is reportedly due to the fact that the male spends more time outside the burrow and the feathers get bleached out by the sun. Seeing them together often shows the differentiation.
    Hope this helps and thanks for posting the pictures.

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