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THE WILSON JOURNAL OF ORNITHOLOGY • Vol. 124. No. 1. March 2012 
The Wilson Journal of Ornithology 124(1): 158-161, 2012 
Observations on Zugunruhe in Spring Migrating Eared Grebes 
Andre Konter 1 
ABSTRACT.—About 200 North American Eared 
Grebes (Podiceps nigricollis califomicus ) at Tule Lake 
Refuge in northern California were observed engaging 
in successive waves of mass pattering and pattering 
flights on 25 May 2011 Most grebes present in a part of 
a canal were involved in this activity. Counts of grebes 
on the morning of 26 May suggest an important portion 
of the Eared Grebes seen in pattering could have left the 
area over night. The behavior was characterized as 
zugunruhe. Directed mass pattering of Eared Grebes 
may contribute to synchronization of the onward 
migration of the birds involved. Received 13 July 
2011. Accepted 10 September 2011. 
North American Eared Grebes (Podiceps ni¬ 
gricollis califomicus) are seldom seen in flight, 
except when they migrate (Beni 1919, Gaunt et al. 
1990). The migration of the species has been well 
studied (Storer and Jehl 1985, Gaunt et al. 1990, 
Jehl 1997. Cullen et al. 1999, Jehl and McKeman 
2002. Jehl and Henry 2010), Cullen et al. (1999) 
indicate migration flights begin around dusk and 
end before dawn. Jehl and Henry (2010) note 
strict correspondence of departure with near-total 
darkness. Grebes tend to gather as the time for 
departure nears (Jehl and McKernan 2002). Pre¬ 
departure activities include group diving, and 
submerging and surfacing in near unison. A 
unique call is given as grebes prepare to depart 
and immediately before actual take-off (Jehl and 
Henry 2010). 
Daytime flights are possibly observed only 
when grebes rebuild their flight muscles prior to 
migration when they may perform one or two 
short practice flights (Jehl and Henry 2010) or 
race across the surface in short practice flights, 
often in small groups (Jehl and McKeman 2002). I 
was surprised to observe a mix of pattering and 
flight by larger groups of Eared Grebes in 
Northern California during daylight conditions. I 
describe these common pattering flight maneuvers 
and discuss their possible meaning. 
1 Museum of Natural History, 25, rue Munster. Lux, 
bourg L-2IM), Luxembourg; e-mail; podiceps@pt.| u 
METHODS 
A study of courtship of Eared Grebes was 
undertaken at Upper Klamath Lake, Oregon, anti 
Lower Klamath Refuge and Tule Lake Refuge, 
both in northern California, from 14 to 27 May 
2011. This region is known to support thousands 
of Eared Grebes each year for nesting, water 
levels permitting. The California refuges hosted 
7,397 and 3,700 nests, respectively, in 2003 and 
2004 (Shuford et al. 2006). Fieldwork was from 
0700 to 1700 hrs each day using a car as a blind. 
The car was parked at suitable places along roads 
near bodies of water and remained immobile for 
up to 3 hrs. The behavior and displays of grebes 
were documented either by photograph, video 
film or immediate voice recording. All observa¬ 
tions of pattering flights are from Tule Lake 
Refuge, part of the Klamath Basin National 
Wildlife Refuges, an artificial water impoundment 
of mostly open water covering -5,200 ha at an 
altitude of 1.200 m and surrounded by croplands. 
The observations were in an area called the 
English Channel (4F 51'202 N, 12L 29' 727 W) 
in the central part of the wildlife tour into the 
refuge. This is an L-shaped canal. <50 m in 
width. It opens at its northern end into large sump 
1 A. an open and shallow area of the lake. It takes 
a left turn after —1.6 km in a straight line from 
north to south (NS canal or NS part of the English 
Channel) and continues east for another 0.5 km 
(EW canal or EW part of the English Channel) 
until ending at a dam-levee that separates it from 
the adjacent larger sump IB (Fig. 1). The entire 
canal is devoid of emerging vegetation. 
1 differentiate between pattering (a grebe with 
flapping wings runs with paddling feet or even 
partially glides over the water surface, but 
remains in constant contact with the water , 
pattering flight (after an initial pattering, a grebe 
is airborne for a distance limited to a few meters 
during which it does not touch the water surtace), 
and real flight (the distance covered while 
airborne exceeds 10 m). It is well established that 
Eared Grebes use pattering in the retreat display 
and during escape/pursuit or more generally 
