Evidence that dorsally mounted satellite transmitters affect migration chronology of Northern Pintails

Jerry W Hupp,Noriyuki M Yamaguchi,Tetsuo Shimada,Sergei Kharitonov,Ken-Ichi Tokita,Paul L Flint,Hiroyoshi Higuchi,John M Pearce,Kiyoaki Ozaki

doi:10.1007/s10336-015-1218-1

Abstract

We compared migration movements and chronology between Northern Pintails (Anas acuta) marked with dorsally mounted satellite transmitters and pintails marked only with tarsus rings. During weekly intervals of spring and autumn migration between their wintering area in Japan and nesting areas in Russia, the mean distance that ringed pintails had migrated was up to 1000 km farther than the mean distance radiomarked pintails migrated. Radiomarked pintails were detected at spring migration sites on average 9.9 days (90 % CI 8.0, 11.8) later than ringed pintails that were recovered within 50 km. Although ringed and radiomarked pintails departed from Japan on similar dates, the disparity in detection of radiomarked versus ringed pintails at shared sites increased 7.7 days (90 % CI 5.2, 10.2) for each 1000 km increase in distance from Japan. Thus, pintails marked with satellite transmitters arrived at nesting areas that were 2500 km from Japan on average 19 days later than ringed birds. Radiomarked pintails were detected at autumn migration stopovers on average 13.1 days (90 % CI 9.8, 16.4) later than ringed birds that were recovered within 50 km. We hypothesize that dorsal attachment of 12–20 g satellite transmitters to Northern Pintails increased the energetic cost of flight, which resulted in more rapid depletion of energetic reserves and shortened the distance pintails could fly without refueling. Radiomarked pintails may have used more stopovers or spent longer periods at stopovers. causing their migration schedule to diverge from ringed pintails. We urge further evaluation of the effects of dorsally mounted transmitters on migration chronology of waterfowl.

Highlights

In recent decades, biologists have increasingly used radio transmitters and data loggers to track long-distance movements of birds (Barron et al 2010)
We hypothesize that dorsal attachment of 12–20 g satellite transmitters to Northern Pintails increased the energetic cost of flight, which resulted in more rapid depletion of energetic reserves and shortened the distance pintails could fly without refueling
A total of 102 radiomarked pintails departed from Japan and were detected in Russia

Summary

Introduction

Biologists have increasingly used radio transmitters and data loggers to track long-distance movements of birds (Barron et al 2010). A critical assumption of tracking studies is that attachment of the tracking device does not influence the study animal in such a manner as to bias the studies’ outcomes. As their use has become more common, the effects of transmitters and data loggers on avian species have been increasingly scrutinized (e.g., Barron et al 2010; Vandenabeele et al 2011; White et al 2013). Relatively few studies have examined whether attachment of satellite transmitters or other tracking devices can affect the timing of avian migration. Additional time at stopovers to replenish reserves may cause the rate of migration for marked birds to differ from unmarked individuals, giving scientists a biased view of the timing of migration events

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