Avian Dynamics Monitoring Program

Program Director: Dr. J. D. Brawn

The ESP Avian Dynamics Monitoring Program began in 1993 and is composed of the following projects:

Banding, Mark-Recapture, and Demographic Analyses.   Sampling on the "traditional" or core mist-net lines along Pipeline Road (in operation since 1968) was conducted during the dry seasons (March) from 1994-2004 and during the wet seasons (July) from 1993-2004 (dry season, 1993 sampling could not be carried out owing to delays in funding and hiring of appropriate personnel). Each sampling period consisted of netting 3 days / site / season rather than the 100 captures / sample protocol that was used previously. Each sampling period consisted of about 600 net hours. We continue to color-mark nearly every bird captured (very large birds such as forest falcons or small hummingbirds are the exceptions). We color banded over 5000 birds and estimate that over 2,000 currently reside on or near the 100 ha census plot. General summary statistics for sampling at the Limbo study site since 1979 are summarized in Table 1. Importantly, mist-net data are being used only for banding and the monitoring/estimation of demographic parameters such as survival rate and population size. Capture data are not being used to estimate local abundances (i.e., densities) of birds.

   Table 1. Summary of sampling from Limbo study-site

Item:        Number
Mist-net captures (1979-2001)            ~   16,5000
 Individuals Captured and Banded (1979-2001)  ~    7,100 (142 species)
 Individuals Color-Banded (1991-2001)  ~    5,000 (90 species)
 Point count and spot-map detections (1993-2000)  ~  50,000 (> 240 species)
 Nests located and monitored  (1996-2000)  ~    2,500 (75 species)
Overall, over 4,000 captures were recorded from 1993-2004. Modeling for re-estimating the demographic parameters of species first analyzed in the 1980's was initiated 1998 and is continuing. New models have been developed and are being used that account for the bias introduced by captures of "transient" birds (Brawn et al. 1999). This project remains as the longest-term demographic study of birds in the Neotropics.

(Spotted Antbird photo curtesy of Ela Hau)
Point Counts, Spot-Mapping and Song Censusing- Song censusing on the 100 ha census plot was initiated in 1994 and allowed a more complete monitoring of avian population dynamics and community structure than that allowed by mark-recapture analyses. The basic protocol for auditory census was 8 minute, unlimited radius point counts. This protocol was carried out on the 100 ha plot, BCI, and other sites from Cocoli, north to Ft. Sherman (the latter efforts were also supported by other funds) through 1998. The entire 100 ha plot was censused in 1994 and 1995. Beginning in 1996, point counts concentrated on a representative 50 ha within the larger plot. The 50 ha was re-censused in 2002 and will be censused again in 2004. In the coming years we will model the point count data (where we recorded al distances from the observer to the bird) using methods developed for distance sampling.
Nesting and Reproductive Ecology - Nests were located and monitored in the 1996 through 2004 breeding seasons. Over 2,500 nests were located on or near the 100 ha census plot. From 2001 to 2004, the nesting study has focused on single species such as Spotted Antbirds and Slaty Antshrikes.