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Distribution & Abundance Maps for 1998

1998 Puerto Rican Breeding Bird Survey
Results and Summary

Fashioned after the North American Breeding Bird Survey, the Puerto Rican Breeding Bird Survey (PRBBS) was begun in 1997 to monitor the long-term status and trends of Puerto Rican bird populations.  The PRBBS consists of 44, 8-kilometer (5-mile) roadside routes randomly located across the island.  Stops are located at 0.8-kilometer (0.5-mile) intervals for a total of 11 stops per route.  At each stop a skilled observer conducts a 5-minute point count recording every bird  heard or seen within a 0.4-km (0.25-mile) radius.  Each route is begun at local sunrise and takes approximately 2 hours to complete.  Routes are run once per year between 15 April and 15 May.  The PRBBS is coordinated by the USGS Patuxent Wildlife Research Center.

Nineteen of 44 possible routes were completed in 1998 and the data submitted to the USGS office, a five percent decline in route coverage from 1997 (Figure 1).  A total of 4037 individuals was counted, representing 63 species — five fewer species than in 1997 (Table 1: opens in a new window).  Among the 63 species were 55 native species, including 11 endemics: Puerto Rican Lizard-Cuckoo, Puerto Rican Screech-Owl, Green Mango, Puerto Rican Emerald, Puerto Rican Tody, Puerto Rican Woodpecker, Puerto Rican Flycatcher, Puerto Rican Vireo, Elfin Woods Warbler, Puerto Rican Stripe-headed Tanager, and Puerto Rican Bullfinch, as well as, three endangered Puerto Rican subspecies: Broad-winged Hawk, Red-tailed Hawk, and Plain Pigeon.  Also included among the 63 species are five introduced species (Rock Dove, Orange-cheeked Waxbill, Warbling Silverbill, Nutmeg mannikin, and Pin-tailed Whydah) and one breeding migrant (Black-whiskered Vireo).  Similar to the results of Kepler and Kepler (1970) and the 1997 PRBBS results, both mean species richness and mean total individuals was greatest for routes in the dry life zone, and both measures demonstrated an inverse relationship with the moisture gradient (Table 2).

   Table 2.  Mean species richness and mean total individuals per life zone
   in 1997 and 1998.

Mean Species Richness

Mean Total Individuals

Life Zone	1997	1998	1997	1998
Dry (N=3/3)	29.3	25.7	306.0	315.0
Moist (N=6/5)	28.3	22.6	264.7	208.8
Wet (N=11/11)	20.0	20.5	217.0	186.2

Except for the Black-whiskered Vireo, which migrates to South America during the non-breeding season, the twenty most abundant species were native permanent residents of which five are endemic species.  The Bananquit was the most abundant species with 764 individuals counted while the Gray Kingbird followed with 323 individuals.  Black-whiskered Vireos (295) were the third most numerous species followed closely by Scaly-naped Pigeons (287) and the Puerto Rican Bullfinch (272).  The Rock Dove was the most abundant introduced species and the twenty-fourth most abundant of all species detected.  The five most abundant species in the dry, moist and wet life zones are listed below (Table 3).

     Table 3. The five most abundant species in the dry, moist and wet life
      zones in 1997 and 1998, in descending order.  See Appendix 1 for
      key to 4-letter species codes.

1997

1998

Dry	Moist	Wet	Dry	Moist	Wet
GAGR	BANA	BANA	SNEG	BANA	BANA
CAEG	GRKI	BWVI	ADWA	GRKI	SNPI
BANA	BWVI	SNPI	BANA	BWVI	BWVI
ADWA	SNPI	PRBU	CAEG	ZEDO	PRBU
GRKI	PRBU	GRKI	GRKI	PRBU	GRKI

The five most abundant species in the wet life zone are the same between the two years although the relative rank of the Scaly-naped Pigeon and Black-whiskered Vireo have switched.  In the moist zone, the only change from 1997 has been the loss Scaly-naped Pigeon from the list and the addition of Zenaida Dove in 1998, while in the dry life zone, the Greater Antillean Grackle has been usurped by the Snowy Egret as the most abundant species in 1998.

The PRBBS is designed to monitor long-term population trends and as such it may take five or more years of data before meaningful trends can be calculated.  Until that time, we will continue to provide annual summaries.

Finally, I would like to thank all the participants of the PRBBS for making this program possible on an annual basis.  The 1998 participants were:  J. Colon, R. Cruz, J. Cruz Burgos, E. Esquilin, A. Hedin, E. Hernandez Prieto, A. Jordan, M. Lopez Flores, J. Marquez, A. Martinez, L. Miranda, E. Nadal, F. Nunez, L. Ortiz, J. Otero, J. Saliva, J. Toro, A. Tossas.

Appendix 1.  Key to 4-letter species codes.
[back to Table 3]

ADWA Adelaide´s Warbler BANA Bananaquit BWVI Black-wiskered Vireo CAEG Cattle Egret GRKI Gray Kingbird GAGR Greater Antillean Grackle PRBU Puerto Rican Bullfinch SNPI Scaly-naped Pigeon SNEG Snowy Egret ZEDO Zenaida Dove

 

U.S. Department of the Interior | U.S. Geological Survey
Patuxent Wildlife Research Center Laurel, MD, USA 20708-4038
http://www.pwrc.usgs.gov/bbs
Operations Contact: Keith Pardieck, email: Keith_Pardieck@usgs.gov
Analyses Contact: John Sauer, email: John_Sauer@usgs.gov
Last Modified: 10/31/01
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