Osa’s Avian Habitats: Losses Are Adding Up Quickly

 

lizandabraham

Liz Jones

Liz and husband Abraham Gallo own and operate Bosque del Rio Tigre, a lodge in Dos Brazos that specializes in birding.  You may reach her at liz@osaadventures.com


 TURISMO


Wood-Stork-are-dependent-on-marshy-areas-

Wood-Stork-are-dependent-on-marshy-areas-

Most of us living on the Osa appreciate and cherish the natural world around us. Developing a clear understanding of the existing animals, their behaviors, and the interconnections between the flora and the fauna is necessary to foresee the impacts of any improvement or development project, both at the personal and community levels.  In many cases, a project’s negative impacts may be greatly reduced with just a little forethought.

Bird populations are diminishing worldwide.  The variety of birdlife in an area is often a good indicator of the quality of habitat and the balance of all species. The reduction of bird species impacts the pollination and seed dispersal of plant species and affects the balance of insect populations, often leading to overpopulation of some of the more bothersome insects.

 Many people only notice the number of birds around them, not the variety, and this can be misleading. Cities are an extreme example of what happens in a depleted habitat. In the city parks you will hear and see many individual birds, but few species.  Some species of sparrow, grackle, some parrots and the Rock Dove adapt well to human habitat requirements, but others just disappear from, or become rare, in a heavily developed area.

In addition to logging, there are a few other common practices on the Osa that have negative impacts on local ecology and the avian populations, but get little attention from the conservation community:

  • Cutting of the forest understory around housing, resorts and farms.
  • Draining of wetlands for housing, yards and palm oil plantations.
  • Cutting and/or improvement of logging roads.

A neighbor of ours in the States loves a neatly groomed yard. He enjoys watching the birds and feeds them year round. After removing all the unruly shrubs and underbrush on the edges of his lawn, he is wondering why he does not see all the same species in his yard that are seen in a neighboring yard with lots of natural underbrush.  He has no idea how he has affected the yard bird populations by his obsessive cleaning.  All species have different habitat and forage needs. For example, you will not see a Brown Thrasher or Common Yellowthroat, if there is no underbrush.  The same concept applies on the Osa.  Cut the understory and many species such as the antbirds, manakins, Riverside Wren and woodcreepers, will disappear from the area.

wattled-jacana-is-quite-rare-in-costa-rica-and-has-been-seen-occassionally-on-the-osa-in-wet-fields

Wattled-jacana-is-quite-rare-in-costa-rica-and-has-been-seen-occassionally-on-the-osa-in-wet-fields

Recently in Dos Brazos, when I was whining about the continuing trend of filling in and draining the wetlands around the village, a local resident said “but there are still lots of birds, we counted “x” species in the village on the Christmas Bird Count.”  What he is missing is that they did not count a single Northern Jacana, American Pygmy Kingfisher or Solitary Sandpiper and counted only one or two Purple Gallinule, White-throated Crake, Green Heron and many other species that were seen regularly and that were quite common on a village walk just 10 years ago. There are still lots of species around, but many dependent on the marshy conditions are now missing or fading fast, and almost no one notices. Of course some of this draining is considered important for mosquito control, but it seems there must be another way.  We have lots of swamp areas on our property and almost no mosquitoes. Why is that?  Maybe the vegetation on the edges creates habitat for frogs and birds that control the insects?

Little by little we are losing avian habitat due to development in remote areas where there are still large stands of decent forest.  It often starts with a logging road (which legally was supposed to be closed after the lumber was extracted). Just about everyone understands logging and clear cutting of forest is destructive, but few realize the additional impacts created by the roads used for access and to extract cut trees.

With the new access, small lots are purchased along the road, houses are built and the road is “improved.” With each dwelling, a bit of habitat is lost.  “Dangerous” trees are cut down and the understory of some forest is often cleared to create a shady, snake-free yard.  Once this understory is cleared and maintained, there is little chance of new trees growing.  Eventually the old trees will fall but there are no new saplings to replace them. Often they are replaced by short or non-native species.  So not only have we removed an important habitat for some bird species by cutting the understory; in time the habitat of other species—the canopy dwellers—will disappear.

Public power will be installed along these new roads. Healthy trees and their branches fall frequently in the tropical rainforests, so a wide swath will be cut to protect the power lines and in so doing, break up the wildlife corridors and make parts of the forest inaccessible to many species.  Sections of buried cable would be a good compromise but this seems unlikely  given the much higher cost to the pulic sector.

Understory mixed flocks (and many mammals) are seriously affected by these roads and housing. Some species with short wings will not cross a wide open area.  So, the flock makeup and the foraging area of the flock are disturbed.  Without the entire flock working together, foraging becomes more difficult and dangerous to the individual birds.  Reproduction will go down due to these added stresses. The birds will adjust eventually, but there may be fewer individuals.  Please see my earlier article on understory birds and how they work together, printed in June 2016.

roseate-spoonbills-were-once-a-common-sight-along-the-roads

Roseate-spoonbills-were-once-a-common-sight-along-the-roads

Understory clearing is technically illegal in most areas but often is done little by little and goes unnoticed by the authorities.  In addition to property improvement, the technique is commonly used to create a “trees in pasture or plantation” situation, which will make it easier to get permission to harvest the trees at a later date.

Another disheartening trend is the proliferation of African oil palm plantations on the Osa. Have you ever noticed how devoid of birdlife they are?  There is enjoyable and exciting birding in just about every habitat type on the Osa except around these plantations.  In theory, there are some raptors that should love the plantations and feed on the rodents that I am told gather to eat palm fruit.   Apparently in Malaysia, palm plantations are where one goes to see certain raptors. I have not tried this locally and suppose I should someday.

Wetlands are often filled or drained for oil palm and the remaining native trees cut. I thought filling or draining wetlands was illegal and wonder why this practice is allowed.  The older plantation on the west side of the road, between the Rio Tigre and Puerto Jimenez, once had a large marshy area that hosted a variety of wetland birds. I would see Roseate Spoonbill, White Ibis, Wood Stork, Northern Jacana, Black-bellied Whistling-Duck, and several species of heron and egret.  Not only have we lost wetlands to the oil palm but we are losing previously rotated pastures and early second growth forests as well.

Bicolored-antbird-an-important-participant-in-the-understory-mixed-flocks-has-very-short-wings-and-will-not-willing-cross-a-wide-open-area

Bicolored-antbird-an-important-participant-in-the-understory-mixed-flocks-has-very-short-wings-and-will-not-willing-cross-a-wide-open-area

So what can we, as property owners do, to help increase the birdlife around us?  Perhaps that wet spot on the property could be an asset with native vegetation, including a few trees, planted on the edges.  Maybe even create a wetland, since we are losing them rapidly.  One could leave areas of the “yard” natural, complete with underbrush and close to other natural-like areas. If the understory is cleared, have some native tree saplings growing and ready to replace the old trees.  Or leave the understory and live with a smaller yard. Paths could be cut through the underbrush with small clearings for air circulation. Even small property owners could make a little area of their yard bird-friendly with a bit of untamed natural garden.

It’s a shame that we are losing the trees and shade in Puerto Jimenez, but I have heard that one of the reasons no one is replacing trees is the difficulty of removing the trimmings since there is no place to dump them.  A community compost and brush dump would be great.

What can we do to help as a community member?  The first thing is to just pay attention and consider the impacts before starting or supporting a building or road project, and by all means speak out as needed.  MINAE is charged with environmental protection, and when things look like they are being done without proper diligence or permitting, speak up to communicate concerns, to the developers, community leaders, and MINAE itself as needed.

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