Programs
Veracruz River of Raptors
Monitoring Project
Biol. Eduardo Martínez Leyva
Coordinator of monitoring project
bichodemonte@gmail.com
vrrmonitoreo@pronaturaveracruz.org
The birds of prey of North America (eagles, vultures, kites, falcons and hawks) move geographically towards temperate zones of the continent due to the extreme living conditions in the winter (low temperatures and food scarcity). Birds of prey aren't the only ones who migrate, most groups of birds that live in these regions and that are affected by climate changes migrate also; however, the migration of birds of prey is one of the most spectacular. These birds form huge flocks of hundreds of thousands of individuals traveling in unison from thermal to thermal towards their southern destinations. Migration is a phenomena that occurs twice a year, beginning in the autumn, before winter reaches the northern hemisphere. Once the cold temperatures end, the birds make their way back towards their nesting territories in the north during springtime.
Due to its geographic location, the state of Veracruz is an obligatory passage way for the bird species which make this trip every year. Because of the topography of the state, the ideal scene is created for these flights: large extensions of flatlands with warm temperatures where rising thermals (columns of ascending hot air necessary for the soaring flight of raptors) are generated. One important factor that accounts for the great numbers of birds that pass through this area, is the presence of mountain ranges. The Eastern Sierra Madre on the western side of Veracruz and the Neovolcanic Transversal Axis in the central part of the state along with the Gulf of Mexico in the east, act as geographical barriers for the birds. Going outside of these limits would mean greater energy cost for the birds as they would find a lack of thermals on which to soar. These barriers direct and compact the flow of the traveling birds, creating what appears as a migration funnel.
The monitoring for the Veracruz River of Raptors program (VRR) is a study that began in 1991. During this time the first counts are made and ideal sites and periods are scouted for. Another core part of the project was the elaboration of a methodology that assured the reporting data in a standardized way; this allows for the information that is gathered yearly to be measurable and comparable. Since 1992 up to date, Pronatura Veracruz has coordinated the project, keeping its objective, the conservation through long term monitoring and observation of migratory raptor populations and their habitat. The count now is officially done during the fall, from August 20th to November 20th, in the towns of Cardel and Chichicaxtle, both situated in the central part of the state of Veracruz. In order to do this, awareness is fundamental in the local people in the areas where the migration occurs. Consequently, in 1995 the environmental education project is initiated to complement the Veracruz River of Raptors Program.
General objective
Promoting the conservation of migratory birds of prey and shorebirds for the long run in the central region of Veracruz.
Goals
- To increment the local interest in bird migration as a result of bird and habitat conservation-oriented activities involving local townspeople.
- To optimize the human, educational and financial resources by developing effective significances that multiply efforts.
- To continue incrementing the migration monitoring database by way of standardized fall counts, and to construct what potentially might be the most important site in the western hemisphere for the monitoring of migrating shorebirds and birds of prey.
Area of study
The central region of Veracruz possesses great biological and ecological richness. This is due to its geographical and topographical location, that rises from the gulf coast to 5,700 meters above sea level. Few places in Mexico exhibit such range in altitude, which creates a vast variety of vegetation. The Eje Neovolcanico Transversal and adjacent mountains of orogenic origin cut the coastal plain of the Gulf of Mexico in two parts close to 19º latitude North. According to Cházaro (1992) it is possible to find six different physiographic zones in the area:
- Plains.
- Rendzinic soil (black soil) region.
- Clay soil region
- Mountains formed by limestone in the Cretacic
- Volcanic Sierra of Chiconquiaco.
- Extinct volcano of Cofre de Perote.
The area's climate is tropical and thermal regimen is classified as regular hot, with abundant rains in summer and beginning of autumn, less in winter due to northern winds. The zone is situated in the Papaloapan hydraulic region, which pertains to the Jamapa river basin and Pajaritos river sub-basin.
Geographic and demographic location
The sites where the migratory bird observations are made are located in the town of Cardel (Lat: 19º 22' North, Long: 96º 22' West) and the town of Chichicaxtle (Lat: 19º21' North, Long: 96º 28' West). The linear distance between these two points is approximately 11 km. The sites have an altitude of 29 and 120 meters above sea level respectively.
The center of Veracruz has been historically subject to intensive land usage, which has resulted in a 75% change in primary vegetation cover (Cházaro, 1992). In the study area, there still exist small patches deciduous and semi deciduous rainforest, coastal dunes, mangroves, and aquatic vegetation. The soil in this area is mainly used now for agricultural and ranching purposes. The principal crops are sugarcane, mango, and chicozapote which require vast extensions of land. Also crops with short cycles are produced, like tomato, papaya, pipian squash, corn, etc. Pesticides are used across the region, despite it being a strategic area for the conservation of birds of prey.
Methods
The method for counting the raptor and shorebird populations is one adapted from the method created by the HMANA (Hawk Migration Association of North America). It consists in direct observations made at the study sites for the duration of the fall migration (August 20th to November 20th ). To guarantee the counts are made regularly, a team of 9 people is established and a work schedule is made for each of the two sites (Cardel and Chichicaxtle).
The detected migratory birds are identified with the use of binoculars and counted. The specie’s name, the hour is was counted, and the number of individuals observed are written down. Every hour, an assistant notes data about the climate, such as wind speed and direction, cloud cover, cloud type, temperature and visibility in kilometers. As well as recording the number of observers and the minutes of actual observation that took place during the hour. The use of field guides is indispensable for bird identification. On occasion, the groups of birds are so numerous that manual counters are necessary to facilitate accurate counts.
Institutions that collaborate with us
The VRR program has two partners which give support in different ways:
both of these U.S. organizations are non governmental.
Financial supporters
Main financial supporters of the program have been:
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