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UNIVERSITY OF KANSAS PUBLICATIONS
MUSEUM OF NATURAL HISTORY
Vol. 10, No. 2, pp. 45-75, 6 pls., 1 fig.
December 20, 1956
Comparative Breeding Behavior of Ammospiza caudacuta and A. maritima
BY
GLEN E. WOOLFENDEN
UNIVERSITY OF KANSAS
LAWRENCE
1956
UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY
Editors: E. Raymond Hall, Chairman, Henry S. Fitch,
Harrison B. Tordoff
Volume 10, No. 2, pp. 45-75, 6 pls., 1 fig.
Published December 20, 1956
UNIVERSITY OF KANSAS
Lawrence, Kansas
PRINTED BY
FERD VOILAND. JR., STATE PRINTER
TOPEKA, KANSAS
1956
Comparative Breeding Behavior of Ammospiza caudacuta and A. maritima
BY
GLEN E. WOOLFENDEN
Transcriber's Note: There are three symbols used in the caption for
Figure b in Plate 1 which are not available in the Latin-1 character
set. They have been noted as follows:
For the black triangle --> [triangle].
For the black dot --> [dot].
For the five pointed star --> [star].
CONTENTS
PAGE
INTRODUCTION 48
MATERIALS AND METHODS 48
DESCRIPTION OF THE AREA 49
FLORA 50
REPTILES 50
MAMMALS 50
PREDATORS 50
PASSERINE ASSOCIATES 51
WINTER STATUS AND SPRING MIGRATION 51
TERRITORY 52
VOICE 58
Song 58
Calls 60
COPULATION 61
NESTS 62
EGGS AND INCUBATION 65
YOUNG 65
Growth 65
Behavior 68
FOOD, FEEDING AND CARE OF THE YOUNG 71
ACKNOWLEDGMENTS 73
SUMMARY 73
LITERATURE CITED 74
INTRODUCTION
Taxonomically the Genus _Ammospiza_ has received the attention of
ornithologists for more than a century. Nevertheless, the behavior of
no species of the genus has been studied extensively. The papers of
Montagna and Tomkins are the only works that mention behavior and
natural history in any detail. There has been an increasing awareness
of the importance of ethological data and of their usefulness in
systematics. For these reasons, I made a comparative study of the
breeding behavior of the Sharp-tailed Sparrow (_Ammospiza caudacuta_)
and the Seaside Sparrow (_Ammospiza maritima_) in New Jersey in the
spring and summer of 1955.
The Seaside Sparrow is restricted to the Gulf- and Atlantic-coasts
of North America, breeding north to Massachusetts. The Sharp-tailed
Sparrow breeds south to North Carolina. The overlap of the
breeding ranges of the two species is therefore small. Furthermore
the forms breeding in the coastal states are restricted to tidal
marshes, and the geographically peripheral colonies of each species
are small. Irregular nesting is the case for the northernmost
colonies of the Seaside Sparrow, on Cape Cod (Griscom, 1944:317),
and the same is probably true for the colonies of the Sharp-tailed
Sparrow on Pea Island, North Carolina, as indicated by Montagna's
failure to locate any breeding birds in July, 1941 (Montagna, 1942b:
256). The center of overlap of the ranges of the two species is in
New Jersey where both forms are abundant and can best be studied
comparatively.
MATERIALS AND METHODS
The adult sparrows were captured and banded, and sometimes the
nestlings were banded. The standard funnel trap, baited with seeds,
proved useless for capturing birds of the Genus _Ammospiza_,
although migrant Savannah Sparrows (_Passerculus sandwichensis_)
readily entered. A Japanese bird net, twenty-five feet long, was
used successfully. Eighty-five Sharp-tailed Sparrows and forty
Seaside Sparrows were banded at two localities.
All of the adult sparrows were banded with United States Fish and
Wildlife Service numbered bands and colored celluloid bands. The
colored bands I used were obtained from the Hinton Supply Company
of New York City, which manufactures them for cage birds. The firm
makes them in seven colors, sold at reasonable prices. With seven
colors, the number of combinations, using only one colored band and
one aluminum band per bird, is forty-two.
In addition, I dyed many adults and all nestlings. Alcoholic
solutions of Victoria Blue B S concentrate and Alizarine Red S
concentrate were used. The males were dyed red, the females blue;
various areas of the body were colored in order further to
individualize the birds. Although the dyes disappeared in less than
a month, the markings were helpful on many occasions.
When an adult bird was captured I always sexed it and ordinarily
weighed and measured it. The nestlings were weighed and measured
daily at intervals of 24 hours. I built a corral of hardware cloth
around one Sharp-tailed Sparrow nest in order to measure the young
after they left the nest. The sex of any adult was ascertained by
examining the cloacal area, as described by Salt (1954:61-75). Sex
as determined by this method was corroborated by internal
examination of the specimens collected.
A pan balance accurate to one-tenth of a gram was used for
weighing. The adults were weighed in a cloth sack, the sack being
weighed each time to prevent error owing to variable moisture and
other factors.
Dragging the marsh with a rope was ineffectual in finding nests.
The birds flushed long before the rope neared them. I found nests
of the sparrows by using a blind. From a blind I would determine
the approximate location of a nest by watching the movements of the
adult birds. Then I would either make a direct search of the
vegetation or move the blind closer to find the actual site.
Many hours were spent in blinds. I had two in operation throughout
the breeding season, and it was from these that most of the data on
behavior were accumulated. Observations were made by means of a 7 x
50 coated binocular and on occasions by means of a 19.6x spotting
telescope.
DESCRIPTION OF THE AREA
The intensive work was carried out on the marshes west of the town
of Lavallette in Ocean County, New Jersey. Further observations
were made at other localities in the county, in particular at the
Chadwick marshes (plate 6), one mile north of the Lavallette site,
where many of the Ammospizas were banded. The breeding Ammospizas
of the localities are the nominate races, _A. c. caudacuta_
(Gmelin) and _A. m. maritima_ (Wilson).
Characteristic of the sand beaches of the Atlantic coast of the
United States are offshore bars which, when exposed, form long bays
parallel to the coastline. These bays become surrounded by marshes
that in turn are inhabited by the two species of _Ammospiza_. The
birds prefer the marshes closest to the ocean (plate 6). I made
trips to the marshes on the mainland side of upper Barnegat Bay and
found only a few Sharp-tailed Sparrows and no Seaside Sparrows in
residence.
The island of the Lavallette marshes that I worked on was
approximately 1400 feet long and 600 feet wide. One-third of the
east central end of the island was covered with sand fill, pumped
there several years before the study was begun (plate 1, fig. b).
The island was also ditched. The four east-west ditches are spaced
125 feet apart; the two ditches perpendicular to these are 340 feet
apart and are situated in the western portion of the island. These
ditches, originally dug as a means of decreasing the mosquito
population, are one foot wide and almost three feet deep. The
excavated earth is deposited in a row paralleling the ditch. The
entire island, excluding the sand fill is not more than two feet
above normal high tide. In August, 1955, abnormally high water, a
result of hurricane "Connie", rose four to five feet and covered
all but the tops of the bushes and a few mounds of sand. Low tides
expose no mud flats for the edges of the marsh are nearly vertical
banks and the water along the edges is more than one foot deep.
The average temperature for July, compiled over a 34 year period at
the Asbury Park weather station is 72.6°F. The average
precipitation from May through August, acquired over the same
length of time, is between 3.5 and 4.5 inches per month.
In spring and summer the prevailing winds are from the south and
southwest. Therefore, the south and west shores of the island are
subject to greater inundations by water. The fact that the island
is unprotected by neighboring islands from the open expanse of the
bay on this side is also of importance in this respect. The north
and east shores, on the lee side of the island, are guarded from
the open bay by nearby land. The exposed southern shores, where
there was open mud and sparse patches of cord-grass, were the
preferred feeding areas of the Seaside Sparrows. Lack of exposed
and open feeding areas may account for the absence of this species
in areas that otherwise seem to fulfill the requirements of the
species.
Two major drift lines were present on the island: one within a few
feet of the waterline consisted mostly of dead eel grass (Zostera
marina), and the other, situated close to the cattail strip,
contained a variety of flotsam (pl. 2, fig. a).
FLORA
The vegetation on the island consisted chiefly of smooth cord-grass
(_Spartina alterniflora_), black grass (_Juncus gerardi_), cattail
(_Typha_ sp.), and marsh-elder (_Iva frutescens_). Other plants
identified on the area were: common reed grass (_Phragmites
communis_) and slender grass wort (_Salicornia europea_). Black
grass grows on the inner, dryer portions of the marsh, and
cord-grass prefers the wetter portions, growing to the edge of the
water. The marsh-elder bushes mostly are restricted to the mounds
of earth dug from the ditches. Cattails, in general, grow in a
narrow band paralleling, but back a few yards from, the shoreline.
Areas of mixed black grass and cord-grass occurred.
REPTILES
Diamond-backed terrapins (_Malaclemys terrapin_) were the only
reptiles recorded from the study island. Several were taken on
land, but the majority were seen in the waters about the marsh.
On June 27 a black snake (_Coluber constrictor_) was seen in a
bushy area bordering a marsh on the mainland side of Barnegat Bay.
A few Sharp-tailed Sparrows were seen in the same locality and a
singing male (G. E. W. 559) with testes 14 x 8 mm. and a female (G.
E. W. 558) with a brood patch were collected.
MAMMALS
Only two species of mammals, both abundant, were present on the
study island: the meadow vole (_Microtus pennsylvanicus_) and the
muskrat (_Ondatra zibethicus_). The muskrats dug burrows beneath
the level of the water into the banks of the island, used the
ditches as routes to the interior of the marsh and built some small
houses, mostly from cattail stems.
PREDATORS
Unless the above named mammals preyed on the sparrows, all of the
enemies of the colony at Lavallette were avian. Both Crows (_Corvus
brachyrhynchos_) and Fish Crows (_Corvus ossifragus_) visited the
local marshes frequently as did a Marsh Hawk (_Circus cyaneus_). I
watched the Marsh Hawk make many passes at what I thought were
sparrows, but the only animal I ever saw caught by the hawk was a
_Microtus_. The sparrows were alarmed when the hawk appeared,
quickly and silently disappearing into the grass.
At least two nests on the Lavallette Marsh were destroyed by
predators in the course of the breeding season of 1955. One nest of
the Seaside Sparrow was empty when I checked it on July 3; on July
2 it had contained four young, three days old. On July 21 I found a
dead Sharp-tailed Sparrow, approximately three days old, lying on a
patch of matted grass. A hole was in the flank of the bird and
blood was present about the bill. This nestling was not from a nest
under observation.
PASSERINE ASSOCIATES
On the Lavallette marshes the only passerine associates of the two
species of _Ammospiza_ were Song Sparrows (_Melospiza melodia
atlantica_) and Long-billed Marsh Wrens (_Telmatodytes palustris
palustris_). Two pairs of Song Sparrows and less than six pairs of
marsh wrens nested on the study area. One Song Sparrow nest was
found and is plotted on the map (pl. 1, fig. b); the other pair
nested somewhere along the east shore of the island. The Song
Sparrows at the east end of the island obtained most of their food
from the grounds of the Lavallette Yacht Club across fifty yards of
water to the east. The pair that nested in the western portion of
the island fed along the sand fill or along the bases of the
marsh-elder. Their nest was built in the most extensive area of
these bushes; it was placed approximately one foot above the ground
in a small dead bush and gained support and concealment from the
surrounding black grass. Three of the four eggs hatched on June 30,
and the young left the nest on July 11. Both parents fed the
offspring.
The marsh wrens fed and nested in the cattails. I never saw these
wrens away from the cattails.
WINTER STATUS AND SPRING MIGRATION
Ocean County is ten miles south of the area treated in Cruickshank's
regional work (1942). He considers both species as rare to casual
winter residents. Concerning the spring migration of the Sharp-tailed
Sparrow he says (p. 456) "The first widespread wave never comes before
April 25, however, and most of the birds arrive in May." He mentions
that late May is the height of migration and that stragglers are
passing through up to the middle of June. The arrival of the Seaside
Sparrow in spring is similar (p. 458): the first widespread movement is
in early May, the peak is reached in the third week of the month, and
stragglers have been recorded through the second week in June.
I was in the field in Ocean County almost daily all spring and found no
Seaside Sparrows and only two Sharp-tailed Sparrows north of Barnegat
Inlet, Ocean County, before May 5. I waded through the marshes at
Chadwick, Lavallette, and Island Beach State Park on April 27 when high
tides covered all of the dense vegetation and saw no sparrows of the
Genus _Ammospiza_. If many had been present on this date I would have
seen them. On May 5 both species were plentiful on the Chadwick
marshes. Furthermore, the Seaside Sparrows were defending territories.
The absence of the two species the previous day indicates a large
nocturnal flight.
It was during the second and third weeks in May that the sparrows of
this genus were most abundant. In this period many unbanded Seaside
Sparrows were in the patches of cattails that were being defended by
the resident males from other territory-holders.
One _Ammospiza caudacuta subvirgata_ (G. E. W. 545) was taken in the
course of the study. It was a female (ovary: 7 x 5 mm.) weighing 15.3
grams ("moderate fat"), taken on June 8, 1955, on a marsh near the
mouth of the Manasquan River on the Monmouth-Ocean County line. This
marsh is decidedly less brackish than the Lavallette and Chadwick
marshes. The specimen was the only _Ammospiza_ seen there and was
probably a migrant, despite the late date; this subspecies is known to
occur late along the Atlantic Coast south of its breeding range.
Cruickshank (1942:454-455) considers the peak of spring migration for
this subspecies to be reached in late May.
To find _A. c. subvirgata_ in a marsh seemingly not saline enough for
the nominate race is not surprising. _A. c. subvirgata_ breeds in
marshes, along the coast of New England, which are almost fresh water
(Montagna, 1942b:256). _A. c. caudacuta_ is only casual away from salt
water.
TERRITORY
In a general treatise on the subject of territorialism, Nice (1933:98),
summarizing Howard, stated: "Territory implies in the male bird
isolation, advertisement, fixation, and intolerance." I concluded from
my observations that all four requirements are exhibited by male
Seaside Sparrows while none of them is well developed in male
Sharp-tailed Sparrows. This subject is discussed separately for the two
species.
Tomkins (1941:38-51) studied populations of _Ammospiza maritima
macgillivrayii_ near the mouth of the Savannah River in South Carolina
and Georgia and concluded that this form is not territorial. In support
of his conclusions, he quoted Nice (1933:90-91) as follows: "Territory
cannot mean just the nest spot when the adults feed in common; this may
be 'nest territory,' but it is a very different matter from a territory
in its strict sense to which parents confine themselves during the
breeding season. Again, the very essence of a territory lies in its
exclusiveness; if a bird's range is not defended, it is not a
territory."
The feeding and nesting grounds of breeding Seaside Sparrows are often
separated by a portion of the marsh which is not used by the birds.
This complicates study of the territorial habits of the species. It
does not mean, however, that the species is not territorial.
The birds studied by Tomkins had separate feeding and nesting grounds.
Concerning this, Tomkins (1941:43) states that "The Seaside Sparrows of
this locality [Savannah River area] often live where the two
requirements [adequate feeding grounds and suitable nesting cover] are
not always together or even meeting, but also where the feeding grounds
and the nesting place are separated by a short distance."
Six of the eight original pairs of breeding Seaside Sparrows of the
Lavallette colony fed in areas separate from those in which they
nested. I found the eight nests of the original residents and banded
and dyed all of the adults. The owners of two nests did not have
separate nesting and feeding areas. One nest was built within fifteen
feet of the south shore of the island, adjacent to the feeding area.
The other was built within a few feet of the north shore. The female of
this nest obtained food along the shore in the immediate vicinity of
the nest. Her mate was absent; in all probability it was the singing
male which I took from a nearby bush, before I found it advantageous to
use the island as a study area.
The remaining six pairs flew to the south or west shores of the island
in order to feed. None of these six nests was more than 100 yards from
the feeding grounds (pl. 1, fig. b).
It was comparatively easy to see that the males defended an area
surrounding the nest. It was more difficult to see that the pairs fed
on separate plots of shoreline, each defended by the male, but I am
convinced that this was the case.
The nest area was defended by the males through singing and chasing. I
saw no instances of a female entering into territorial disputes;
nevertheless, I did see a female chase a Sharp-tailed Sparrow away from
the vicinity of her nest.
Tomkins (1941:46) did not consider the song of _A. m. macgillivrayii_
to be "a declaration warning other birds away." After observing the
behavior of males of _A. m. maritima_ I am convinced that advertisement
of intolerance is the primary purpose of song in this species. An
account of the activities of a male Seaside Sparrow on May 6 on the
marsh at Chadwick demonstrates this point. In an hour (6:01-7:01 a.m.)
the bird sang 395 times, an average of 6.6 times per minute. He faced
his nearest singing competitor when singing, which in the course of
this hour was usually a male approximately 250 feet away across a
creek. The two competitors almost always alternated their songs and
frequently the singing of one seemed to stimulate the other bird to
sing. Although the song of the Seaside Sparrow is short and unmusical
it is loud, especially when compared with the song of the Sharp-tailed
Sparrow. Elevated perches such as the tallest cattail stems or isolated
bushes were used as singing and observation perches.
The chase of the Seaside Sparrow is not vigorous, but in all cases the
intruder was seen to give way to the defender. I saw no physical fights
between Seaside Sparrows. Chase by a defending bird was close to the
ground and directly toward the intruder. Sometimes the attacking male
emitted chipping notes when first sighting or flying towards his
adversary.
In the hour of observation mentioned above, no other Seaside Sparrows
entered the bird's territory, which consisted of a strip of cattail and
shoreline, 250 feet long and no more than 25 feet wide. At other times
Seaside Sparrows did enter this male's territory, and he drove them out
as soon as he saw them. Savannah and Swamp Sparrows, which for a few
weeks migrated through the area, were not chased, but Sharp-tailed
Sparrows were chased at times.
Several times I flushed a particular male Seaside Sparrow from the
northwest tip of the Lavallette study island so that it flew to the
island to the north. Seaside Sparrows of this north island immediately
made themselves conspicuous by chipping and then drove the non-resident
individual back to its own territory.
The first time I heard what is described below as the social call of
the Seaside Sparrow was on June 30 when an unbanded sparrow alighted in
a marsh-elder bush near a nest. The individual called twice as it came
near. The sound immediately aroused the owners of the nest and the male
flew directly toward the strange bird. The intruder quickly and
silently flew away.
My field notes refer to many other instances of territorial defense of
the nesting area; it seems superfluous to cite them here.
Additional proof of territorialism in Seaside Sparrows was obtained by
identifying and plotting the location of all the marked individuals,
which I saw each day while systematically traversing all the available
habitat on the island. Surprisingly, I did not once record a resident
Seaside Sparrow in what I considered another male's territory in the
month and a half (June 15-August 1) that I worked on the island at
Lavallette.
The fact that the adult Seaside Sparrows did not search for food
communally, or that different pairs did not utilize one particular area
at different times was most apparent when the pairs were feeding young.
From the blinds I first noted that the adults from any given nesting
territory always flew in the same direction towards the shore. After
moving a blind closer to the shore I noted that once an adult arrived
at the open or sparsely vegetated shoreline, that adult restricted
itself to a certain portion of the shoreline. These shoreline
territories were plotted on field maps and appear on the map in plate
1, figure b. One method used to ascertain the boundaries of these
shoreline feeding territories was a census taken from a boat. Many
times I circled the island in a skiff identifying the marked sparrows
as they appeared along the shore. The feeding sparrows were always
found in the same areas around the island. Straight lines can be drawn
between the nest sites and feeding areas of each pair of Seaside
Sparrows without having any lines cross (pl. 1, fig. b). These lines
correspond to the flyways used by each pair to go to and return from
the feeding area. I consider the area defended about the nest, the
segment of shoreline used by a pair of Seaside Sparrows and the
connecting flyway to constitute the territory of a male Seaside
Sparrow. If the flyways of any of the pairs had crossed, a situation of
mutual exclusiveness would not have existed and a territory could not
have been defined for the species.
It is generally agreed that territorial species engage in a minimum of
fighting. Song and display have been evolved to substitute for actual
combat which demands a greater amount of energy. Additionally, the mere
presence of an individual in an area previously established as its
territory probably serves to keep birds of nearby territories away. I
think that male Seaside Sparrows defend the feeding area and flyway as
a part of their territory by advertisement through use of these areas.
The birds at Lavallette rarely sang on the feeding grounds and I noted
only a few chases originating there. The sparrows rarely landed along
the flyways. The constant use of these areas probably served as
territorial defense, however. This supposition is supported by the fact
that feeding areas and flyways of different pairs were mutually
exclusive.
Nice (1941:457) divided territory into six categories. Type A (mating,
nesting, and feeding ground for young) is the type exhibited by the
Seaside Sparrow. The territory of a male Seaside Sparrow must contain
an area of open mud and/or sparse vegetation where food can be obtained
and also enough suitable cover to conceal the nest. I suspect in the
case of the few males studied on the marshes at Chadwick that the
territories the males established (strips of cattails and adjacent
shoreline) did not have suitable nesting cover, because these males
were unmated on June 15 when I left this study area because of human
interference. Suitable nesting cover and feeding areas were separated
by short distances of unusable marsh for most of the sparrows on the
Lavallette study area. This fact caused the adults to commute from one
site to the other. Photographs of shoreline habitat suitable for
feeding by Seaside Sparrows appear in plate 2.
The area defended about the nest tended to follow the rows of
marsh-elder bushes (pl. 3, fig. a), probably because these bushes
supplied suitable song and observation perches. The segments of
shoreline used by each pair were less than 75 yards in length and
scarcely 20 feet wide. I never recorded Seaside Sparrows foraging in
the interior of the marsh.
Sharp-tailed Sparrows were more abundant than Seaside Sparrows on the
marshes at Chadwick and Lavallette. Sharp-tailed Sparrows were the more
difficult to net because of the peculiar organization of the colonies.
This organization, described below, also made nests of that species the
more difficult to find. Only intensive netting at both localities
produced enough marked individuals for me to study the breeding
behavior of the species.
At Chadwick, where I netted most of the 85 Sharp-tailed Sparrows that I
banded, my efforts were concentrated on one segment of the marsh.
Marking made it evident that the males were not territorial, although
they did confine themselves to what might appropriately be called a
breeding home range, the area to which an individual confines itself in
the course of one nesting attempt. Observations of marked birds also
indicated that there was considerable overlap of the breeding home
ranges of individual males.
I recorded a few marked Sharp-tailed Sparrows often enough and over a
long enough period (more than one month) to gain a good idea of the
size of the breeding home range of the males, which I estimate to be
three to four acres. This estimate was made at Chadwick, where large
areas of suitable uniform habitat occur. Females are more secretive
than males, but seem to restrict themselves to areas considerably
smaller than those of the males. My observations of two females that
were feeding young indicated that each female restricted herself to an
area of less than one acre. Female Sharp-tailed Sparrows possibly are
territorial, although I recorded no disputes that would substantiate
this possibility.
If I am correct in my estimates of size of breeding home range in
Sharp-tailed Sparrows (males, three to four acres; females,
approximately one acre), certain observations made by Montagna and me
are readily explainable.
My netting operations indicated a surplus of male Sharp-tailed Sparrows
in a given area. At Chadwick, I netted as many Sharp-tailed Sparrows as
I could, without regard to sex. Here I captured 39 males and 16 females
(six individuals remained unsexed). On the Lavallette study island,
netting was more selective; here I attempted to net the females of the
nests I found. The sex ratio at Lavallette was 15 males to eight
females (one juvenile was not sexed). Three of the eight females were
netted at their nests.
Montagna (1940:196) decided from collecting and observations that male
Sharp-tailed Sparrows either outnumbered the females or were
polygamous. The results I obtained from netting seemed to indicate a
surplus of males. Banding, however, showed that in the breeding season
males range over a larger area than do females. With this knowledge,
the discrepancy between the number of males and females captured is
explainable without an unbalanced sex ratio. If the males range over an
area four times as large as that of the females, theoretically, four
times as many males should be caught at every placement of the net
provided the net remained in place long enough to capture all the birds
using the area. In practice, this is essentially what occurred.
Other behaviorisms of this species indicate that it is not territorial.
The song of the male is not loud and does not seem to be an
advertisement to other birds. In fact, the song of this species is so
quiet and lengthy when compared to that of the Seaside Sparrow that I
at first thought I was hearing "whisper" or "practice" songs. These
qualities of the song seem to indicate that the "advertising" function
of song of territorial species is lacking or unimportant in
Sharp-tailed Sparrows.
I suspect that male Sharp-tailed Sparrows do not even know where nests
are. On July 18 at 7:00 a.m. I was watching a nest from a nearby blind
when an unbanded male (I saw the individual sing later) appeared. As
the bird foraged through the black grass, it headed directly toward the
nest. When the male was almost one foot from the nest the incubating
female left. She ran from the tussock and flew a short distance away to
a cattail stem. From here she watched the male, which seemingly
oblivious continued foraging, coming within inches of the nest. As the
male walked away from the nest the female returned. At 8:00 p.m. the
same day I was in the blind again. The female was out searching for
food when a different, banded male appeared. In his foraging, the male
walked up on the grass stems over the nest. The male apparently saw the
young (two had hatched on July 17 and one on July 18) for he turned his
head and seemed to peer down under the stems. The female appeared (with
food) as he was doing this; she flew directly toward him and he flew
away. The male was not seen near the nest in later observations.
On July 1 (6:50 a.m.) I was in a blind near another nest as the female
approached with food for the young. At this moment a male appeared and
the female immediately flew away. The male perched on a tussock within
two feet of the nest, sang, and then flew off. The female reappeared in
a few seconds without the food. She searched through a clump of black
grass four feet from the nest, caught a small, pale green insect, fed
it to her one young (there were also two eggs in the nest) and began
brooding.
VOICE
_Song_
Only males of the two species sing. The normal song of the Seaside
Sparrow lasts just under two seconds, the buzzing final note
constituting three-quarters of the song. Saunders (1951:257-258)
describes this song as short, and buzzlike, beginning with two or three
short, rather faint notes and ending in a trill at first loud but
fading away toward the end. The introductory notes are followed by a
higher-pitched, loud, strongly accented, but buzzy note. This note is
usually higher than the final trill and connected with it. The song has
been written as _tup tup ZEE reeeeeeeeee_ and _tup TEE tle reeeeeeeeeee_
(Saunders, 1951:257), _cutcut_, _zhé-eeeeeeeee_ (Peterson, 1947:232)
and _che-zheéeege_, _che-zhée_, _che-wéege_, _chur-zhée_ and
_too-szheée_ (Stone, 1937:910). My field notes contain the following:
_CHUR-er eeeee_, _CHUR eeeeee_ and _oka-CHE weeeee_. These variations
in the phonetic representation of the songs are attributable mostly to
the birds. Not only is there variation among individuals, but also
individuals vary their songs. Birds that I heard giving a characteristic
song suddenly sang a different type for awhile, and then reverted to
the original. The bill is elevated and opens considerably with each
note; the head bobs with the loud note. Typical singing postures are
shown by Tomkins (1941: pl. 3).
The song of the Sharp-tailed Sparrow, as described by Saunders
(1951:256-257), is short and insectlike, introduced by one or two short
notes; the remainder is a somewhat wheezy trill, growing fainter
towards the end. Sometimes there are two trills on different pitches,
and occasionally a final short, low note. The quality is as though the
sound _sh_ ran through all but the introductory notes. Saunders writes
these trills as: _tsup tsup shreeeeeeeee_ and _tip tish eeeeee
shaaaaaaay_. The bill is opened slightly with each note, as I saw when
I watched a singing bird with the sun directly behind it. Montagna
(1942a:116) noted that _A. c. caudacuta_ sang less often than the more
northern _A. c. subvirgata_.
Both species have specialized flight songs, but in the birds that I
studied these songs were infrequent and seemingly unimportant. The
flight song of the Seaside Sparrows consisted of a double version of
the normal song. Although I heard it only a few times, the flight song
of the Sharp-tailed Sparrow seemed slightly louder than the normal
song. This song is given by both species as the bird flutters upward
ten or 20 feet and glides back down.
Singing begins at daylight and decreases at 9 or 10:00 a.m. when the
temperature rises. On cloudy days singing seemed to last longer.
Towards dusk singing again increases, but not to the frequency of the
morning peak.
The major differences between the songs of the two species are in
loudness, length, and frequency. The fact that the Seaside Sparrow
sings louder than the Sharp-tailed Sparrow is mentioned by Stone
(1937:906). On windless days I heard singing Seaside Sparrows more than
200 yards away; Sharp-tailed Sparrows were inaudible at distances of
more than 40 yards. The song of a Seaside Sparrow is rarely longer than
two seconds; the song of a Sharp-tailed Sparrow usually lasts for
almost 20 seconds and consists of a variable number of phrases like
those described by Saunders. A Seaside Sparrow that I watched for one
hour sang 395 times or 6.6 times per minute. I doubt that any of the
Sharp-tailed Sparrows sang more than 20 times per hour, although I made
no comparable count.
Additionally, Seaside Sparrows sing from exposed perches such as tall
cattail stems and tall or isolated marsh-elder bushes. Sharp-tailed
Sparrows do not often use conspicuous perches for singing. They sing
while on the ground or when in flight. They do use exposed perches as
observation posts and occasionally sing from them.
Seaside Sparrows often face their nearest neighbor when singing and
alternate songs with this bird. The one time Sharp-tailed Sparrows
almost always sing is when they are involved in fighting. In such a
case the several birds sing simultaneously.
Seaside Sparrows began singing the morning after their nocturnal
arrival. For resident birds, singing is at its maximum at this time and
is maintained at a high level throughout incubation. At hatching of the
eggs, singing declines sharply; males then are busy aiding in care of
the young. Males that have successfully reared a brood rarely sing
after the young leave the nest.
Sharp-tailed Sparrows sang infrequently when they first arrived, and
singing did not reach its peak until late May. By August singing had
almost ceased in this species.
Song of the Seaside Sparrow functions importantly in the establishment
and maintenance of its territory. Newly-arrived males sing vigorously.
In the Sharp-tailed Sparrow I think song is merely an expression of
sexual excitement because song does not reach maximum frequency until
the females arrive and become receptive to the males.
Differences in song correspond to differences in territorial behavior.
The distinct, loud song, sung often and from exposed perches, which is
frequently alternated with that of the nearest competitor, is given by
the Seaside Sparrow, a territorial species. The indistinct, quiet song,
sung infrequently and often from unexposed places belongs to the
Sharp-tailed Sparrow, a non-territorial species.
_Calls_
Seaside Sparrows give a soft, lisping call note, probably the one
referred to by Saunders as a squeaky _tseep_ (1951:258), that functions
as a social call. When migrants were numerous on the marshes at
Chadwick I heard this note often. At Lavallette I did not hear it
until June 30 (work began there on June 16) and then it was from an
unbanded, non-resident bird. In late July and in August the number of
non-resident sparrows increased and the social call was heard often. I
never heard a resident bird give this call. On December 29, 1955, on a
marsh at the mouth of the Manasquan River on the Monmouth-Ocean County
line, a group of wintering Seaside Sparrows frequently used this call.
I do not know whether the Sharp-tailed Sparrow has a comparable call.
Both species emit alarm notes. Although variable, the Seaside Sparrow
has two general types. One, recorded by me as a short _chip_ or _tick_
was given by both sexes whenever I was near a nest. The other type, a
high, sharp _tsip_, is indicative of a higher degree of excitement.
When I captured young already out of the nest, or when I investigated
nests containing young old enough to depart, the adults gave this call.
The tail is jerked downward each time this note is given.
The alarm call of the Sharp-tailed Sparrow is not so loud as that of
the Seaside Sparrow and it is not given so often. I described it as a
short _tsick_ or _tsuck_. Females emitted such calls when I was at
their nests or when male Sharp-tailed Sparrows came near their nests.
Males may have a similar call, but I never recorded it. Montagna
(1942a:116) remarks on the quietness of this species. This is
especially evident when one compares Sharp-tailed Sparrows with Seaside
Sparrows.
PLATE 1
[Illustration: FIG. _a_. An aerial photograph of the Lavallette study
island. One inch equals approximately 375 feet. The area covered by
sand has been extended since this photograph was taken. This is
indicated in figure _b_ of this plate.]
[Illustration: FIG. _b_. Map of the Lavallette study island. All
fringillid nests that I found are indicated and the territorial
boundaries of the Seaside Sparrows are shown.
[triangle]--Seaside Sparrow
[dot]--Sharp-tailed Sparrow
[star]--Song Sparrow]
PLATE 2
[Illustration: FIG. _a_. The south shore of the Lavallette study island
showing the two major driftlines and the sparsely vegetated areas. This
is the feeding habitat of the Seaside Sparrow.]
[Illustration: FIG. _b_. A close-up view of a segment of the shoreline.
Note the spacing of the clumps of cord-grass (_Spartina alterniflora_).
A six inch ruler propped against a 12 inch stick is included to
indicate the size and spacing of the plants.]
PLATE 3
[Illustration: FIG. _a_. The inner portion of the marsh on the
Lavallette study island showing the rows of marsh-elder bushes (_Iva
frutescens_) and the extensive areas of black grass (_Juncus gerardi_).
Areas of mixed black grass and cord-grass appear in the foreground. All
the nests of Sharp-tailed Sparrows were found in the areas of black
grass. Four of the eight nests of Seaside Sparrows were in the
marsh-elder. One of the blinds that I used is shown in this
photograph.]
[Illustration: FIG. _b_. A mated, banded pair of Seaside Sparrows in a
dead marsh-elder bush near their nest. Note the abdomen of a moth
protruding from the bill of the female on the right.]
PLATE 4
[Illustration: FIG. _a_. A female Sharp-tailed Sparrow at the entrance
to her nest. The throat on this bird is dark because of dye applied by
me.]
[Illustration: FIG. _b_. The nest of a Sharp-tailed Sparrow viewed from
above. Stems of black grass were parted to take the picture. The outer
rim of this nest (lower right) is made of living stems of black grass.]
COPULATION
In late June at the Lavallette area there was an influx of unbanded
Seaside Sparrows. Certain of these new arrivals established territories
in areas unoccupied by the remaining original residents. These new
residents were birds that probably had unsuccessful nestings elsewhere.
Because of tropical storms that almost covered the island with water in
August, I doubt that any of these late nestings were successful. On
July 7 at 8:30 a.m., while watching a pair of these new arrivals, I
recorded my only observation of copulation in the Seaside Sparrow. The
female seemed to be searching for a nest site when copulation occurred.
The female crawled about in a marsh-elder bush seemingly testing the
various forks in the branches for size. The male followed her,
remaining a few inches above and behind. Several times the two birds
disappeared in the lower branches and were hidden by the surrounding
black grass. Finally, while the female squatted on a branch the male
mounted. He fluttered his wings before mounting and continued to do so
as coition took place.
I began observations at Lavalette on June 16, too late to observe
copulation of the early residents. All the nests contained eggs by that
time. At Chadwick, pair formation seemingly never occurred, at least
with the males I was studying. The territories established by males at
Chadwick contained few marsh-elder bushes. Possibly females, finding no
suitable nest sites, refused to accept these territories.
Copulation in the Sharp-tailed Sparrow was observed several times. It
occurs most frequently in the course of, or immediately following, a
fight between several males. I do not know what instigates the
gathering of several males into these groups; it may be a certain
behaviorism of a female, or possibly, merely the appearance of a
female. Montagna (1942a:117) was convinced that females of _A. c.
subvirgata_ were present in these fights. On the other hand, in two
instances with _A. c. diversa_ where he collected all the birds in the
group, no females were present. Twice, at Chadwick, my observations
indicated that females of _A. c. caudacuta_ were not always involved in
these groups. In these instances all the birds in the group had
previously been banded and diagnosed as males. Possibly a female was
the original stimulus of these groups, and she may have disappeared
while the males were fighting with each other. I found it difficult to
distinguish fighting males from a copulating pair. On June 3, however,
a banded pair was observed. Copulation occurred on the ground. The male
fluttered his wings as he mounted and the female remained motionless.
Copulation lasted approximately three seconds; immediately thereafter
the male flew to a nearby cattail stem and the female climbed a tussock
of grass and chipped quietly. This same female was seen to copulate
with other males, and males were observed copulating with several
females.
_A. m. maritima_ is monogamous, the pair-bond being maintained
throughout a breeding cycle. _A. c. caudacuta_ is promiscuous,
relations between the sexes being limited to copulation. For _A. c.
subvirgata_ a relationship other than promiscuity has been intimated
(Lewis, 1920:587-589). Concerning observations of the nest he found at
Yarmouth, Nova Scotia, Lewis wrote: "The nest was found after I had
quietly watched the parent Sparrows for about an hour, while they were
bringing food to their young.... The male sang from time to time from a
piece of driftwood on the marsh about 30 feet distant from the nest.
When I was examining the nest and the young birds, the parents made no
demonstration for some minutes, but later they came near and uttered
chip's, much like those of Savannah Sparrows."
NESTS
I found the nests of all eight pairs of Seaside Sparrows which nested
on the Lavallette study island in 1955. Four nests were supported by
marsh-elder bushes, three of which were dead. These nests were placed
low enough to be hidden by numerous stems of black grass, as were the
other four nests. Of the remaining four nests, three were placed in
tussocks of black grass and the fourth one gained support mostly from
cord-grass stems. The eight nests ranged from 9 to 11 inches (9.6 inch
average) from the rim to the ground, the four nests in the bushes being
the highest. The outside diameters of the nests ranged from 3 to 4.5
inches (3.9 inch average) and the outside depth varied between 2 and
3.5 inches (2.7 inch average). Seven of the nests had an inside depth
of 1.5 inches; the other one was only an inch from the rim to the
floor. The inside diameter of the cup varied between 2 and 2.5 inches.
As mentioned above all eight nests were shielded by stems of black
grass. Stems were not woven over the nests by the birds; rather it was
the choice of the nest sites that resulted in the concealment. The only
plant used for nest material was black grass.
In all cases the black grass limited the directions from which the
nests could be entered. Six of the nests were approached from a
direction varying between northeast and southeast. The prevailing winds
of spring and summer are from the south and southwest; the black grass
consequently leans in the opposite direction. The remaining two nests
were entered from the northwest. These were nests built in marsh-elder
bushes where the grass stems were held upright by the branches of the
bushes.
One nest, built in a small dead marsh-elder bush, was tilted by the
growth of stems of black grass which were used for support on one side.
This tilting did not cause the contents to spill, but, I judged, did
cause the adults to desert the nest.
Seven nests of the Sharp-tailed Sparrow were found; two of these were
old nests. Four of the five nests used in the breeding season of 1955
were found on the Lavallette marsh study area, the other one I
discovered on the Chadwick marshes. Two young Sharp-tailed Sparrows
that I saw at Lavallette were not from nests I found, nor were they
from the same nest. Therefore, a minimum of six Sharp-tailed Sparrows
bred on the Lavallette island. Measurements were taken of only the five
nests that were used in 1955. The Sharp-tailed Sparrow builds its nest
closer to the ground than does the Seaside Sparrow. The five nests were
five to six inches off the ground; the two nests of a previous year
appeared to have been no higher. The Sharp-tailed Sparrow nests were
built in areas where black grass was the predominant plant, and the
nests were constructed entirely from this grass. The outside diameters
varied from 3 to 4.25 inches (3.4 inch average). The outside depth of
the nests varied from 2 to 3.5 inches (2.8 inch average). The inside
depth was 1.5 inches in all nests and the inside diameter ranged from 2
to 2.5 inches (2.1 inch average).
Harrison F. Lewis (1920:587) studied a nest of _A. c. subvirgata_ in a
small salt marsh near Bunker's Island at the southern end of Yarmouth
Harbor, Yarmouth, Nova Scotia, which he found on June 12, 1920. For
details of this nest I quote Dr. Lewis. "The nest proper was a neat,
round cup of fine, dry, dead grass, with some horsehair in the lining.
Its foundation consisted of some small masses of 'eel-grass' and roots.
Its dimensions were: inside diameter, 2.5 in.; outside diameter, 4.5
in.; inside depth, 1.5 in.; outside depth 2.375 in. It was elevated
above the general surface of the marsh by being placed on the top of a
low, grassy ridge, about fourteen inches high, formed from material
thrown up when a ditch was dug across the marsh, many years before.
During some storm a mat of dead 'eel-grass' had been left on top of
this ridge, and this had later been lifted by the growing marsh grass,
leaving several inches between it and the ground. The nest was placed
on the northwest edge of this mat, about half of the nest being under
it, while the other side was sheltered and concealed by grass about six
inches high. The nest was not sunk in the ground at all."
Two of the nests found were entered from the north-northeast, the other
three from the east-southeast. All five nests were sheltered above by
stems of black grass. Three of the nests were beneath a layer of dead
black grass where a clump of erect living stems parted the mat. One
nest (pl. 4, fig. a) was situated where cattail stubs held the black
grass somewhat erect. Green stalks as well as dead stalks were woven
into a canopy over this nest. Another nest was constructed on a mat of
black grass under and among numerous horizontal living stems, some of
which were woven into the outer lining of the nest (pl. 4, fig. b).