Results of NYBC Taiwan 2019

Site-Based Results

From December 15, 2018 to January 7, 2019, NYBC Taiwan’s 1,365 participants performed bird surveys at 179 sites (Fig 1, Table 1), recording 312,948 individuals from 325 species. A total of 63 of the 179 sites were located in Important Bird and Biodiversity Areas (IBAs, Fig 2). 

The southwest coast and northeastern plains were hotspots in both species richness and abundance in winter (Fig 3, 4).

Fig 1. NYBC 2019 Site Map (credit: Yong-Lun Lin)         Fig 2. NYBC 2019 Site Map Highlighting Surveys Done in IBAs (credit: Yong-Lun Lin)

 

         

Fig 3. NYBC 2019 Bird Species Richness (credit: Yong-Lun Lin)   Fig 4. NYBC 2019 Bird Abundance (credit: Yong-Lun Lin)

 

Species Numbers and Population Trends

 

NYBC Taiwan 2019 recorded 325 species from 312,948 individuals, including all of Taiwan's 29 endemics. Over 10,000 individuals were counted for the following species: Eurasian Tree Sparrow (Passer montanus), Kentish Plover (Charadrius alexandrinus), Great Cormorant (Phalacrocorax carbo), Dunlin (Calidris alpina), Northern Shoveler (Spatula clypeata), Black-winged Stilt (Himantopus himantopus) and Light-vented Bulbul (Pycnonotus sinensis). NYBC data from 2014-2018 showed that this year's survey mascot, the Pied Avocet, has shown a population increase over the last five years. In 2019, 4,380 individuals were recorded at a total of 23 sites (Fig 5).

Fig 5. The distribution of Pied Avocet (Recurvirostra avosetta) in 2019 (credit: Yong-Lun Lin) and the population trend from 2014 to 2018 (credit: Cheng-Te Hsu).

NYBC uses an "rtrim" package of R 3.5.1 has been used to examine the population trends of waterbirds, including waterfowl, shorebirds, and wintering terns. This method is a sensitive to statistical significance, making it adept at detecting growth or decline in populations based on count data.

 

Analysis of the data collected over the last six years has led to the following findings. Populations of Painted Snipe (Rostratula benghalensis), Long-toed Stint (Calidris subminuta), and Common Snipe (Gallinago gallinago) have decreased significantly from 2014 to 2019 (all p<0.05, Fig 6). Meanwhile, populations of Eurasian Wigeon (Mareca penelope), Eastern Spot-billed Duck (Anas zonorhyncha), Northern Shoveler (Spatula clypeata), Northern Pintail (Spatula acuta), Tufted Duck (Aythya fuligula), Great Egret (Ardea alba), Intermediate Egret (Ardea intermedia), Little Egret (Egretta garzetta), Eurasian Coot (Fulica atra), Red-necked Stint (Calidris ruficollis), and Black-headed Gull (Chroicocephalus ridibundus) increased significantly between 2014 and 2019 (all p<0.05, Fig 7-8).

Fig 6. Population data for Painted Snipe (Rostratula benghalensis), Long-toed Stint (Calidris subminuta), and Common Snipe (Gallinago gallinago) show a significant decrease from 2014 and 2019 (all p<0.05, credit: Arthur Bureau).

 

Fig 7. Population data for Eurasian Wigeon (Mareca penelope), Eastern Spot-billed Duck (Anas zonorhyncha), Northern Shoveler (Spatula clypeata), Northern Pintail (Spatula acuta), and Tufted Duck (Aythya fuligula), showing significant increases from 2014 to 2019 (all p<0.05, credit: Arthur Bureau).

 

Fig 8. Population data for Great Egret (Ardea alba), Intermediate Egret (Ardea intermedia), Little Egret (Egretta garzetta), Eurasian Coot (Fulica atra), Red-necked Stint (Calidris ruficollis), and Black-headed Gull (Chroicocephalus ridibundus) showing significant increases from 2014 to 2019 (all p<0.05, credit: Arthur Bureau).