Part 4

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.