Pale-legged Leaf Warbler/Sakhalin Leaf Warbler, Yangkou, Rudong, Jiangsu, China, 1 May 2014. (Craig Brelsford)

Pale-Sak Calls: An Addendum

by Craig Brelsford
Founder, shanghaibirding.com

In the wake of my recent post on distinguishing Pale-legged Leaf Warbler from Sakhalin Leaf Warbler by call, I have been hoping to find more members of this species pair in Shanghai. On 4 Sept. 2017 at Pudong’s Cape Nanhui, my hopes were fulfilled in a big way. At the Magic Parking Lot (30.884889, 121.968222), not one but both species were calling.

Below, the recordings I made with my Olympus DM-650 pocket recorder. The first Sakhalin recording was made at Microforest 4 (30.953225, 121.959083), 7.7 km north of the Magic Parking Lot on the coastal road. The others were made at the Magic Parking Lot.

Note the higher frequency of the calls of Pale-legged—on average a full kilohertz higher. The difference is discernible by the keen listener, but nothing tells the story better than the spectrograms.

To summarize what I argued in the previous post: The calls, as well as the very distinctive songs, of Pale-legged Leaf Warbler and Sakhalin Leaf Warbler are diagnostic—that is, they differ markedly and consistently and are a reliable basis for an ID. The diagnosability of the calls of the two species has been affirmed by various researchers, among them Yap et al. (2014; Birding Asia 21: 76–81).

Sakhalin Leaf Warbler Phylloscopus borealoides, call, Microforest 4 (30.953225, 121.959083), Cape Nanhui, Pudong, Shanghai, 4 Sept. 2017 (00:02; 528 KB)

Audio spectrogram of call of Sakhalin Leaf Warbler.

Sakhalin Leaf Warbler, call, Magic Parking Lot (30.884889, 121.968222), Cape Nanhui, Pudong, Shanghai, 4 Sept. 2017 (00:07; 1.4 MB)

Audio spectrogram of call of Sakhalin Leaf Warbler.

Pale-legged Leaf Warbler Phylloscopus tenellipes, call, Magic Parking Lot, 4 Sept. 2017 (00:19; 3.7 MB)

Audio spectrogram of call of Pale-legged Leaf Warbler.

Pale-legged Leaf Warbler, call, Magic Parking Lot, 4 Sept. 2017 (00:41; 7.9 MB)

Audio spectrogram of call of Pale-legged Leaf Warbler.

Pale-legged Leaf Warbler, call, Magic Parking Lot, 4 Sept. 2017 (00:10; 2 MB)

Audio spectrogram of call of Pale-legged Leaf Warbler.

Pale-legged Leaf Warbler, call, Magic Parking Lot, 4 Sept. 2017 (00:01; 332 KB)

Audio spectrogram of call of Pale-legged Leaf Warbler.

Featured image: Pale-legged/Sakhalin Leaf Warbler, Jiangsu, May. Some of the salient characteristics of Pale-Sak are pointed out. Separating Pale-legged from Sakhalin on the basis of plumage and bare parts is not possible; because this bird was neither singing nor calling, it cannot be determined to which of the two species it belongs. (Craig Brelsford)
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Craig Brelsford

Craig Brelsford is the founder of shanghaibirding.com. Brelsford lived in Shanghai from 2007 to 2018. Now back home in Florida, Brelsford maintains close ties to the Shanghai birding community and continues his enthusiastic development of this website. When Brelsford departed China, he was the top-ranked eBirder in that country, having noted more than 930 species. Brelsford was also the top-ranked eBirder in Shanghai, with more than 320 species. Brelsford’s photos of birds have won various awards and been published in books and periodicals and on websites all over the world. Brelsford’s Photographic Field Guide to the Birds of China, published in its entirety on this website, is the most Shanghai-centric field guide ever written. Brelsford is a graduate of the University of Florida and earned a master's in business administration at the University of Liege, Belgium.

2 thoughts on “Pale-Sak Calls: An Addendum”

  1. Good stuff. I am glad the call frequency is turning out to be a valid trait. We had a rather low sample size for our Yap et al. paper, but I was still sure that the 1 kHz difference can’t be a coincidence.

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