Aphelocoma jays represent a group ofhighly social and diverse species in terms ofgeographical range and behavior, and thegenus includes 3 distinct lineages based onmorphology, plumage, and genetic data: scrubjays, Mexican jays, and unicolored jays (AOU1998, McCormack et al. 2011). The IslandScrub-Jay (Aphelocoma insularis), a speciesrestricted to Santa Cruz Island of the Califor-nia Channel Islands archipelago, has longbeen recognized as a distinct species based onmorphology and plumage (Pitelka 1951, AOU1998) and more recently through molecularanalyses (Delaney and Wayne 2005, Delaneyet al. 2008). The life histories of many Aphelo-coma species, including precopulatory displaysand reproductive behavior, are well known(see Brown 1963, 1964, Webber 1984, Wool -fenden and Fitzpatrick 1996). However, despitenaturalists visiting Santa Cruz Island for overa century (Henshaw 1886), we found no infor-mation regarding the precopulatory behaviorof the Island Scrub-Jay.

One potential reason for this gap in under-standing of fundamental Island Scrub-Jay lifehistory is that this species has been describedas shy compared to mainland species (Bent1964). Also, Santa Cruz Island is isolated andcharacterized by thick vegetation and ruggedtopography (Schoenherr et al. 1999). Theisland is largely inaccessible to the generalpublic, thereby restricting the number ofpoten tial observers and making opportunisticobservations of behaviors such as copulationunlikely. Alternatively, the lack of observations ofIsland Scrub-Jay precopulatory behavior couldbe due to the relative lengths of pair bonds inour study plots. Color banding and behavioralobservations during the breeding season beganin 1975 (Atwood et al. 1990), and systematicIsland Scrub-Jay nest monitoring has beentaking place since 2008 (Caldwell et al. 2013).Island Scrub-Jay breeding peaks from mid-March through April (Atwood 1978), and moni -toring typically begins in mid-February to

Western North American Naturalist 79(2), © 2019, pp. 275–279

First documented observation of Island Scrub-Jay(Aphelocoma insularis) precopulatory display

REBECCA G. CHEEK1,*, MICHELLE L. HARRIS2, AND ANNA KENNEDY3

1Department of Biology, Colorado State University, Fort Collins, CO 805212Humboldt State University, McKinleyville, CA 95519

3El Granada, CA 94018

ABSTRACT.—We report what we believe is the first documented observation of Island Scrub-Jay (Aphelocoma insu-laris) copulation behavior. We compare our observations to the behaviors of other Aphelocoma jays with the aim of iden-tifying potential species-specific elements. There are observable differences between the precopulatory display of theIsland Scrub-Jay and that of more distantly related Aphelocoma jays. The display of Island Scrub-Jay and that of theclosely related California Scrub-Jay (Aphelocoma californica) are very similar despite the species being isolated fromeach other for approximately 1 million years.

RESUMEN.—Reportamos sobre lo que creemos que es la primera observación documentada acerca de las conductasde copulación de la Chara de Santa Cruz (Aphelocoma insularis). Comparamos nuestras observaciones con los compor-tamientos de otros tipos de charas (Aphelocoma jay) con el objetivo de identificar posibles elementos característicos dela especie. Hay diferencias observables entre los despliegues precopulatorios de las Charas de Santa Cruz y las de susparientes lejanos, Aphelocoma jay. Los despliegues de las Charas de Santa Cruz y los de su especie hermana, la CharaCaliforniana (Aphelocoma californica), son muy similares, a pesar de que las especies han permanecido aisladas entreellas durante aproximadamente 1 millón de años.

*Corresponding author: rebecca.g.cheek@gmail.com

275

allow for the observation of courtship behav-iors before breeding begins. Most pairs inthe long-term study plot (8 out of 14) havebeen together for at least 3 years (mean 3.67,SD 1.91 years). Writtenberg (1968) and Ver-beek (1972) both noted a lack of precopulatorydisplays between older pairs in other corvidspecies. If precopulatory displays are rarer inolder pairs, this would further reduce the like-lihood of observing such behavior in IslandScrub-Jay focal pairs. Here, we describe what we believe is thefirst documented observation of copulatorybehav iors in the Island Scrub-Jay. Our pri-mary goals are (1) to provide the first descrip-tion of the Island Scrub-Jay precopulatory dis-play and (2) to compare our observation tothose of other Aphelocoma species in orderto identify potential differences in precopula-tory display behavior. At 07:50 on 11 April 2018, a known pair ofcolor-banded Island Scrub-Jays was spottedapproximately 3 m away from our position.Both the male and female were banded within2 km of the territory they have maintained forapproximately 3 years. When first observed,the birds were within 0.5 m of each other andwere facing each other. They then hopped

approximately 15 m up a slight hill to the cen-ter of a 1-m-wide dirt path. The path was shel-tered on both sides by 2-m-tall Ceanothusarboreus. The male then rounded in front ofthe female and walked back and forth in a semi -circle several times. He maintained an uprightposture, facing the female with his bill raisedand the tail slightly fanned, with the tips of therectrices dragging on the ground. The wingswere pulled away from his sides and slightlyflared. The female held a similar posture asthe male, pivoting her body to face him as hemoved around her but otherwise remainingstationary (Fig. 1). The male then approachedfrom her right side. Immediately the femalecrouched low so that her body was close to theground with her tail slightly raised. The malethen mounted her briefly. Copulation lastedbetween 1 and 3 s. Following copulation, thepair remained close for a few seconds beforeflying away together. This whole interactionlasted less than a minute. We heard no vocali -zations, despite a lack of wind and our proxim-ity to the pair. Despite this species evolving in isolationfor approximately 1 million years (McCormacket al. 2011), many elements of the copulationbehavior of Aphelocoma jays are seen in the

276 WESTERN NORTH AMERICAN NATURALIST (2019), VOL. 79 NO. 2, PAGES 275–279

Fig. 1. Posture of the Island Scrub-Jay during the precopulatory display (female on the left, male on the right). Draw-ing by Michelle Harris.

CHEEK ET AL. ♦ A. INSULARIS PRECOPULATORY DISPLAY 277

T

ABLE1.

Com

parison of rec

orde

d pr

ecop

ulatory be

haviors am

ong 5 mem

bers of the

gen

us Aphelocom

aan

d the Steller’s Jay (Cyanocitta stelleri;o

utgrou

p). Y

= obs

erve

d, N

= not

observed

, U =

unc

lear, O

= occ

asiona

lly.

Beh

avior A. coerulescensa A

. califo

rnicab

A. insularisc A. w

ollweberid A

. unicolore C. stellerif

�tail fann

ed Y Y

Y

Y

N Y

and

not raised

�vo

caliz

ations

Y Y

U

N

N

Y

�vo

caliz

ations

U

Y U

N

N

U

Hea

d bo

wed

in �

O

N

N

Y N N

�tilted toward

� Y

Y

U

Y N Y

Spread

wings

Y Y

(Ada

ms 20

16) Y Y

N Y

180°

arc arou

nd �

Y, h

op Y, w

alk

Y

, walk Y N Y

(som

etim

es w

alk) (Ada

ms 20

16)

Flared he

ad Y

, hea

d U

U

Y, hea

d an

d br

east N

U

and

breast fea

thers

Bill probing

Y

N

N

N

N

Y

Food

carrying

N

N

N

Y N N

�resp

onse

Beg

ging

posture

Initia

te or Cou

rtsh

ip and

/or W

ings ope

n N Retur

n disp

lay

(Fe

rgus

on et a

l. 20

16) retur

n disp

lay be

gging po

stur

eExtra pair pa

tern

ity 0

(Tow

nsen

d et a

l. 2

1.4 7.8 4

0 (L

i and

Brown 20

00); Frequ

ent, no

Rare, no

(%

of o

ffspr

ing) 20

11) (D

elan

ey 200

3) (Desrosiers 20

14) 16

(Eim

es et a

l. 20

05) m

olec

ular w

ork molec

ular w

ork

Mating system

C

oope

rativ

e N

onco

operative Non

coop

erative Coo

perativ

e Coo

perativ

e Non

coop

erative

(C

armen

198

8) (C

aldw

ell 2

013)

a Woo

lfend

en and

Fitz

patrick 19

96b W

ebbe

r 19

84c N

ew obs

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tions

rep

orted in th

is pap

erd B

rown 19

63e W

ebbe

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d Brown 19

94f Brown 19

63, 1

964

Island Scrub-Jay (Table 1). Nearly all recordedobservations of Aphelocoma copulations notea fanned, unraised tail during precopulatorydisplay, with the male’s body tilted towardsthe female as he moves in a 180° arc aroundthe female with his wings slightly flared(Brown 1963, Webber 1984, Woolfenden andFitzpatrick 1996). We did not observe a similarbody tilt in the male Island Scrub-Jay, but thatcould be due to the slight angle at which weobserved the pair. One potential difference inthe Island Scrub-Jay display was the lack ofobserved male vocalizations, as described forA. coerulescens and A. californica (Webber1984, Woolfenden and Fitzpatrick 1996). Nordid we note a flaring of head or breast feathersas seen in A. wollweberi and A. coerulescens(Brown 1963, Woolfenden and Fitzpatrick1996). Given that the observed jays had main-tained a territory for at least 3 years, the previ-ously mentioned lack of precopulatory dis-plays recorded in older pairs of other corvids(Writtenberg 1968, Verbeek 1972) did not holdtrue for the Island Scrub-Jay in this instance.Aphelocoma unicolor is thought to copulate atthe nest with no precopulatory display (Web-ber and Brown 1994). Most of the elements ofthe copulatory behavior of Aphelocoma jaysappear to be conserved, with a few observabledifferences in Island Scrub-Jay behaviors.Given that our conclusions are based on a sin-gle observation, perhaps these should only beconsidered potential differences to be con-firmed or refuted with more extensive obser-vations of precopulatory displays within Aphe-locoma. Documentation with audio and videorecording would be ideal.

ACKNOWLEDGMENTS

We thank The Nature Conservancy for pro-viding housing and logistical support over thepast 10 years of Island Scrub-Jay conservationand monitoring efforts. M. Gamboa, C. Marshall,S.M. Henrichs, and 2 anonymous review ersprovided helpful comments.

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Received 8 September 2018Revised 22 January 2019Accepted 8 February 2019

Published online 12 June 2019

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