Skip to main content
  The Houston Canoe Club
Share our Joy of Paddling!








P.O. Box 925516
Houston, Texas
77292-5516



The Houston Canoe Club 

is a Paddle America Club


Link to ACA

Add Me To Your Mailing List
HomeNL-2012-08 Bird Island Mystery

Bird Island Mystery: A Theory
July 7, 2012
by Joe Coker

 

Where are all the birds? That was the big question on the Bird Fest 2012 paddle as we approached Bird Island on Lake Charlotte, eagerly expecting an active rookery scene, like last year. The date was July 7, perhaps a little late in the season. Regardless, we thought we’d see at least something. But not! Nothing. Not even a trace. Not even a single empty nest. Big mystery! Why the total desertion?  Why had the birds completely avoided the island this year but still occupied Buzzard Roost? Had something scared them away? Not likely. I speculate it’s something else.

The low nesters like the egrets and particularly the roseate spoonbills seem to love the vines and thick undergrowth. Many of the photos I’ve taken in past years show the spoonbill nests tucked back deep in the vegetation, well under cover.  That’s where they seem to like it best. One might question, why we also see many of their nests much more out in the open. I suspect that paradox has a lot to do with the old adage: The early bird gets the worm. But in this case, it’s the Prime Real Estate. The first couples on the scene, seem to get all the good spots… photos show much more mature babies in the “viney” nests.  The late comers are relegated to the “low rent district” mostly on the outskirts where they must make do with more bare branches and much less cover. The babies there seem frequently much younger and smaller, signaling later nesting and/or perhaps less attention.
 

 

Spoonbills tucked deep
in the vegetation
  Spoonbills   Mature babies in
viney nests

Mature & viney   Late-comers on
outskirts

 

High ground most of the time at Buzzard Roost seems to ensure a persistent “jungle-like” environment there year after year… always lots of thick undergrowth and high-growing vines… perfect.  A reliable nesting spot for the birds, it’s also a famous gator breeding ground. Likely some symbiosis at play… the gators keep all the lesser predators like coons, otters and nutria from invading the rookery, while the fallen eggs and chicks keep the gators fat and happy.

So, what about Bird Island? It obviously got its name for good reason… Thick undergrowth and high-growing vines often engulf this isolated stand of hardy cypress, attracting tons of birds. However, it’s not always like that. And here-in lies (I believe) the answer to the mystery. Since the land at Bird Island is much lower than at Buzzard Roost, conditions on the island are much more variable… a direct function of the water level on the lake. This fact seems to have a direct bearing on attractiveness for the birds. When the gauge is over about 7.5 feet, Bird Island is completely submerged. Conversely, at lower water levels more and more of the island is exposed. Rich soil gives rise to dense undergrowth… And the birds flock there! 

 
Water gauge history    Sharing nests
A review of gauge history over the past number years seems to confirm the correlation.  Going back to 2007, there was a prolonged period of on-average low water (except for a few spikes) all the way through the spring of 2011. Bird Island was LUSH and attracted a plethora of birds. When Dave Kitson and I visited the site that July, the water level was already up and land was hidden. Nevertheless, there was still adequate coverage to attract the birds. Conditions weren’t optimal though, and space was very limited… so much so that egrets and spoonbills were observed to be actually sharing nests in the few relatively decent spots.  Meanwhile, things were teeming at Buzzard Roost.

By midyear 2011, controlled levels on the Trinity raised Charlotte to consistently over 9 feet for the rest of the year. At the start of 2012, levels occasionally spiked to over 12 feet and ever since, have averaged above 8. Thus, for about a year, Bird Island has been almost constantly underwater… Still pretty (for us), but too desolate for wildlife. No land. No thick undergrowth. No birds.

Natural events there have also threatened the fragile existence of the Bird Island rookery. What seems to bring life, can also take it away. Paradoxically, in 2008 what had been a favorite safe-haven, became a trap… a deadly strainer. When hurricane Ike hit that September, the island was loaded with birds. With nowhere to escape, many were killed as the hurricane-force winds slammed them into the vines like so many gnats on a screen door. John Rich, Ken Anderson and I witnessed the gruesome aftermath the following spring. Dozens of bird skeletons were hanging everywhere…  an amazing, sad, macabre scene. 

   

   

The lake level was under 7 feet and there was much exposed land enabling us to go ashore and explore.  Even though nesting conditions seemed good, there was strangely little bird activity… presumably a generational gap resulting from the previous year’s chaos. Even activity on Buzzard Roost was negligible. Although the storm hadn’t left as much carnage there (less high trees to create as bad a strainer effect), a brief exploration showed other residents besides the birds had also suffered the harsh effects of the hurricane… we found the skeletal remains of a large (9ft.) gator.

   
 Exploring ashore    Exposed land   Llittle bird activity

 
Gator remains   John with gator

 
Healthy activity  
The birds might have never returned to Bird Island. But they eventually did. Even as powerful as the storm was, with continuous low-water levels for the better part of the next several years, conditions were good. There was dry land, the undergrowth came back on the island as strong as ever and so did the birds. Witness the photos of last year’s still relatively healthy activity, even though the water level had recently begun to rise.  But now the scene is different… everything has been underwater for about a year… the plants and vines are gone. And so are the birds. If land resurfaces long enough in the future, the process should repeat. The dense vegetation will come back. The birds will again be attracted… and presumably, Bird Island will again be an active rookery… At least, that’s my theory. Time will tell.

 


Joe Coker, bird whisperer