Satellite Telemetry

MOVEMENTS AND RESOURCE UTILIZATION OF FOUR SPECIES OF DUCKS CAPTURED IN THE MID-PARANA RIVER BASIN, ENTRE RIOS AND CORRIENTES PROVINCES, ARGENTINA

Introduction:

            Large populations of ducks, a variety of species, and liberal bag-limits make Argentina a popular destination for both North American and European waterfowl hunters.  A GOOGLE search of the world-wide web for duck-hunting outfitters produces hundreds of web-sites offering duck hunting opportunities in Argentina.  But a similar web-search for information on the biology, behavior, or management of ducks in Argentina produces meager results.  This study, utilizing satellite radio telemetry, is aimed at filling the existing information gap on four duck species common in the hunter’s bag: the rosy-billed pochard (Netta peposaca; RBPO), white-faced whistling duck (Dendrocygna viduata; WFWD), black-bellied whistling duck (D. autmnalis; BBWD), and the fulvous whistling duck (D. bicolor; FUWD).  While there are several other species equally common to the hunter’s bag, these four species of ducks have a sufficiently large body mass (1000g, 700g, 700g, 700g respectively) to successfully carry a radio transmitter.

Objectives:

1. Describe the annual movement patterns of these four duck species.
2. Locate and identify important nesting, molting, staging, and wintering areas.
3. Based on the above findings, identify and describe the resources important to the continued success of these four species.

Techniques:

            Ducks were captured at various locations within the floodplain wetlands of the Parana River in Entre Rios and/or Corrientes Provinces during August.  Because these wetlands of the Parana River are popular hunting sites for the commercial hunting outfitters, capture efforts were delayed to the end of the traditional hunting season.  Capture sites were pre-baited to attract feeding ducks, and then equipped with walk-in funnel traps.  The plan is to capture 10 to 15 of each specie, with a maximum of 40 total during each of three years (2008, 2009, 2010).

            A USGS veterinarian will implant a 26g PPT 100 transmitter (Microwave Telemetry, Inc) into each duck’s abdominal (coelemic) cavity.  The transmitter possesses an external (percutaneous) antennae, and with the use of a catheter, is passed through the duck’s back. Following the surgeries, ducks were held in a field enclosure for observation, until ready for release (around 2-5 days). The ducks were then released at the site of capture.

            Following surgery and release back onto the Parana River wetlands, satellite tracking (ARGOS) began immediately.  Location data was posted monthly on a bi-lingual Spanish-English website.  An Argentine researcher was responsible for data analyses and maintenance of the website with assistance from our personnel.

            During the second and subsequent years of the study, locations determined from the satellite telemetry will be of particular importance.  Location sites will be visited on the ground and the nature of the natural resources described.

Results:

            During August, 2008, several hundred ducks of the four species were captured with the white-faced whistling ducks being the most commonly caught.  The largest ducks of each of the four species were selected for instrumentation which was done at the Don Pablo Ranch near Goya, Argentina with the use of an improvised surgery and holding facility.  Unfortunately, only 20 of the 40 transmitters that were manufactured arrived for use and the other 20 were temporarily misplaced during shipment.  The 20 ducks instrumented included 3 BBWD, 2 FUWD, 8 WFWD and 7 RBPO.  Ducks are now being tracked and data is mapped with Google Earth to determine locations of the four species during the post hunting season.  The ducks are now in the breeding season and it is hoped that after molting they will return to the same wintering areas on Don Pablo Ranch.

Analyses of the habitat used by the ducks (based on locations) during the one year following release revealed that wetlands formed the highest percentage of habitat for BBWD, RBPO, and WFWD.  Lake areas formed the highest percentage of habitat for FUWD.  When locations following release were determined based on the country in which the duck was located it was determined that three species (BBWD, RBPO, and WFWD) were located most commonly in Argentina, but FUWD were most commonly located in Brazil.  All species used Brazil for some of the year and RBPO and WFWD were located in Paraguay and WFWD were located in Uruguay for a small percentage of their time. 

During August 2009, 436 ducks of five species were captured with techniques similar to those used in 2008.  Forty ducks were instrumented and included 10 BBWD, 9 FUWD, 10 WFWD, 10 RBPO, and one South American comb duck (Sarkidiornis melanotos; COMB).  One duck RBPO died within a week of release, but other ducks are doing well and being monitored with satellite telemetry and data obtained through the Argos system.  One duck that was banded, but not instrumented in 2008, returned to Don Pablo Ranch and was captured.

Table 1.  Species habitat preferences as defined by percentage of total location 3, 2, or 1 satellite.

Table 2.  International movement by species as defined by percentage of total location 3, 2, or 1 satellite fixes.