Condor, 81:269-277 @ The Cooper Ornithological Society 1979

COMPETITION AND PREDATION: HERRING VERSUS LAUGHING GULLS

JOANNA BURGER

Gulls of the Lams generally nest co- When Herring Gulls began breeding in lonially, often in mixed- assem- more southern areas, they chose to nest in blages. For example, Herring Gulls (L. ar- salt marshes, the customary nesting areas of gentatus) in Europe nest with Lesser Black- the large and stable Laughing colonies backed Gulls (L. fuscus; Brown 1967, (Burger 1977). Although differences in nest MacRoberts and MacRoberts 1972) and site selection were noted initially, these dif- Black-headed Gulls (L. ridibundus; Green- ferences decreased as Herring Gull colo- halgh 1974); and in Ring- nies expanded. Overlap in colony and nest billed Gulls (L. delawurensis) nest with site characteristics is obvious in several California Gulls (L. culifomicus; Vermeer New Jersey colonies (Burger and Shisler 1970) and Herring Gulls (Southern 1970). It 1978). Since the first report of Herring Gulls is often difficult to determine whether such on Clam Island (Rogers 1965), the colony assemblages are actually mixed, or if mon- has increased from 50 to 1,200 pairs where- ospecific colonies simply exist side by side. as the Laughing Gull colony of 4,000 to When assemblages are mixed it is often im- 6,000 pairs remained about the same size possible to ascertain whether they are so by through 1976. choice or because of a lack of suitable nest My primary objectives in this paper are to sites. The rate of competition and predation examine how these species interact tempo- by one or both species has not been inves- rally and behaviorally, and to determine the tigated. In this paper I examine competitive result of these interactions in terms of nest- interactions and predation between Laugh- ing space allocation and reproductive suc- ing Gulls (L. utricillu) and Herring Gulls on cess. Clam Island, New Jersey, from 1976 through 1978. Laughing Gulls on the east coast of the United States traditionally nest in Spurtinu STUDY AREA AND METHODS salt marshes (Bent 1921), although at the limits of their range they frequently nest on Clam Island is a 54 ha salt marsh island in Barnegat Bay, Ocean County, New Jersey (39”45N,’ 74”OBE).’ dry land (Nisbet 1971, Dinsmore and Several channels cut the island into four major islets. Schreiber 1974). Thus, when Herring Gulls Slight differences in elevation result in differences in expanded southward in the early 1900s’ into tidal inundation and vegetation. Predominant vegeta- Maine and Massachusetts, they came into tion is ~nartinu ulternifloru (5I%), S. putens (20%) and bushes (lou and Bucchuris, 4%) having a maximum direct conflict with Laughing Gulls (Nisbet height of 1.5 m. Ponds normallv cover 25% of Clam 1971, Drury and Kadlec 1974). As early as Island, although this varies depending on rains and 1943, Herring Gulls nested with Laughing storm tides. Gulls in a sand dune colony at Muskeget I gathered all data from 15 March to 30 July 1976, Island, Massachusetts (Noble and Wurm 1977 and 1978. Aerial surveys by helicopter aided in establishing study sites, ascertaining nesting bound- 1943). Despite initial differences in habitat, aries of both species, and censusing total numbers of the Laughing Gulls disappeared (Nisbet, nesting pairs. From early March until mid-May I ob- pers. comm.). Increases in Herring Gulls in served interactions between the two species. From the northeast also have been associated mid-April until the end of June all of the Herring Gull with decreases in Common Terns (Sterna nesting areas, and all (1977 and 1978) or 25% (1976) of the Laughing Gull nesting areas were checked two to M-undo; Nisbet 1973). four times a week to determine breeding chronology In the 1950s’ and 1960s’ Herring Gulls and hatching success. The percentage of Laughing again expanded their breeding range, nest- Gulls nesting in each vegetation type was determined ing as far south as North Carolina with by helicopter and ground surveys. I determined relative marsh elevations by designat- Laughing Gulls (Hailman 1963, Parnell and ing a fixed point on the marsh as zero, and measuring Soots 1975). They nested on the upper parts all elevations with respect to this point by using a Leitz of domes on man-made islands while self-leveling level accurate to 0.01 cm. Elevations of Laughing Gulls occupied low swales be- all nests in a 20-m wide transect served as a basis of comparison from 1976 to 1978. tween the domes. Where Herring Gulls Since predation might occur between species, I set were absent, Laughing Gulls nested farther up 12 dummy nests of eel grass (Zosteru) in each of up the domes (Parnell and Soots 1975). the major habitat types (dense bushes, sparse bushes, 270 JOANNA BURGER

LG IIIIIIIIIIIIIIIIIIIIIIIIIIIIII-mIIIIm Laughing Gulls arrive in early to mid- HATCHING April and immediately select territories. 11111 FLEDGING H G IIB~IIII~~~C~~,~~P~,III,I,,II,I,,IEGG~ wm They spend more time standing about their territory than Herring Gulls, and do not con- MARCH APRIL MAY JUNE JULY struct nests until a day or so before egg-lay- FIGURE 1. Breeding chronology of Herring Gulls ing (see Fig. 1). The brief laying period (HG) and Laughing Gulls (LG) in New Jersey. does not overlap the hatching period. They fledge at the same time as Herring Gulls. grass) in a transect from the center of the Herring Gull POPULATION TRENDS colony to the center of the Laughing Gull colony. Each nest, separated from other dummy nests by at least 15 The Laughing Gull population on Clam Is- m, contained two Herring Gull eggs obtained from a land remained relatively stable (about 5,000 nearby colony. These nests were checked hourly for pairs) until the mid-seventies (Rogers 1965, the first six hours, and every two hours thereafter until F. Lesser and E. OMalley,’ pers. comm.). In all eggs disappeared. Since my behavior might influ- ence predatory behavior, I set up a series of dummy 1976, 2,000 pairs bred on one of the four nests with eggs in another part of the colony where I main islets, and 3,000 pairs bred on the could observe both series from a hide, while my assis- north islet. By 1977, only 500 pairs bred on tants checked the original experimental nests. Clam Island proper, and 3,500 pairs bred on the north islet (Fig. 2). In 1978, only 500 RESULTS pairs nested on the whole Clam Island com- BREEDING SYNCHRONY plex, while 3,500 pairs nested nearby on Herring Gulls winter in New Jersey away High Bar Island. from the colony. They arrive on the colony In 1964 only 50 pairs of Herring Gulls area in early March, and begin defending bred on Clam Island (Rogers 1965). From territories in mid-March (see Fig. 1). Nor- 1976 to 1978 the Herring Gulls increased mally they build nests a few days after se- from 800 to 1,200 pairs, and expanded over lecting sites. However, 1978 was exceed- most of the islets. In 1976 the Herring Gulls ingly wet and Herring Gulls built nests only predominantly nested on the largest islet in a day or two prior to egg-laying. The first high areas with bushes. In subsequent years eggs are laid in mid-April, although the they expanded into the grass, choosing the peak of egg-laying is not until early May. highest areas scattered about the marsh. Due to the extended egg-laying period, hatching of early eggs begins before late COLONY AND NEST SITE SELECTION nesters have laid. Fledging begins in early Herring Gulls in New Jersey tended to form July, and peaks in mid- July when the young new colonies in the high areas of marshes form groups in the bay. containing bushes (Burger 1977). At Clam

1976 1977 1978

n HERRING fg LAUGHING

“4 FIGURE 2. Area occupied on Clam Island by Herring Gulls (black) and Laughing Gulls (grey). GULL COMPETITION AND PREDATION 271

90- HERRING GULL * v) : : ,: :I 5 ; : 100

75

1976 1977 75

50

25 25 PERCENT Oi%lM 7;SLAND

FIGURE 3. Vegetation, elevation and location of

Herring Gull nests in 1976 (dashed line) and 1978 (sol- I I I I id line), and of Laughing Gull nests for 1976 (dotted 011 patens iuncus phrag. bushes line) and 1978 (diamonds). FIGURE 4. Location of Laughing Gull nests on Clam Island (lines) and in the rest of Ocean County, N.J. (rectangles) as a function of vegetation (and thus ele- Island they also nested in the bushes, and vation) arranged in order of height with S. altern@ora were restricted to that habitat until the early being the lowest. 1970s.’ In 1976 a few pairs nested in the Spartina patens areas adjacent to the main colony (Fig. 2). By 1978 almost 40% of all volved shifting colony locations away from nests were in Spartina grass (Fig. 3). For a low S. aZterni$Zora islands. This shift was complete discussion of nest site overlap be- necessitated by several weeks of high tides tween species see Burger and Shisler in late April which inundated the areas nor- (1978). mally used. The Laughing Gulls that re- In general, Laughing Gulls selected S. mained and nested on Clam Island, how- alterniflora marshes for nesting (Bongiorno ever, did not shift into the higher and drier 1970, Montevecchi 1975, Burger and Shis- S. patens and bushes, but remained in S. ler 1978). On Clam Island, Laughing Gulls alternijora. The attempted to nest in nested predominantly in S. alterniflora, al- the highest S. alternijbra areas near the though pairs initially attempted to establish Herring Gull nesting areas (refer to Fig. 3), territories in the higher S. patens areas. In but were forced to move due to behavioral 1976 and 1977 the Laughing Gulls nested interactions with Herring Gulls (see below). in the highest grass areas available that The percentage of Laughing Gulls nesting were devoid of Herring Gulls. In 1976 I in S. alterniflora on Clam Island did not counted all of the Laughing Gull nests in differ from 1976 to 1978, although the per- Ocean County (Fig. 4). The percentage of centage nesting in these low areas on other gulls nesting in S. alternijlora (90%) was colonies did shift dramatically. Few Her- the same on Clam Island as on the other ring Gulls nested in the other Laughing colonies. In another large colony farther Gull colonies, and those were limited pri- south at Brigantine National Wildlife Ref- marily to Phragmites and bushes. Thus, in uge they also have nested predominantly in a year of normal tides, Laughing Gulls nest S. alternijlora grass for fifteen years (C. in S. aZternijZora regardless of the presence Beer and M. Impekoven, pers. comm.). In of Herring Gulls (which so far have not nest- 1978, however, the pattern differed. Laugh- ed in S. alternijlora). In years of high flood- ing Gulls elsewhere nested predominantly tide Laughing Gulls shift to higher locations in S. patens (67%), and most others (27%) where Herring Gulls are not present, but nested in still higher areas ofjuncus, Phrag- do not do so when Herring Gulls occupy mites and bushes. In some cases this in- these areas. 272 JOANNA BURGER

50 A

50- 30-

25 lo- z ’ z 2 i kk B ii 30.

75. lo--

50, “\ \ 15 23 27 1 5 APRIL MAY 25 FIGURE 6. Total aggression observed in areas of Herring and Laughing gull overlap (A), and percent of aggression due to intersuecific interactions (B). See t&t for further explanation. 4-LI p2di+ches iuncus, bushes FIGURE 5. Percent of Laughing Gull nests in var- (Bourn and Cottam 1939), yet they yield ious habitats (top) compared to percent survival (bot- benefits for Laughing Gulls. tom) after a heavy rain on High Bar Island. BEHAVIORAL INTERACTIONS The importance of Laughing Gulls shift- Competition. In the previous sections I ing to higher nesting areas was dramatically have shown that 1) Herring Gulls arrive ear- shown in early July of 1978. A two-day lier than Laughing Gulls, 2) the character- heavy rain (as much as 15 cm of rain in five istics of nest sites overlap, 3) nesting Her- hours) drenched Clam and High Bar is- ring Gulls have increased whereas nesting lands. The rain was accompanied by very Laughing Gulls have decreased on Clam high tides which again inundated vast areas Island and 4) Herring Gulls have expanded of S. alternijlora. After the storm I surveyed the area they occupy on Clam Island where- High Bar (Fig. 5). The upper graph shows as Laughing Gulls have contracted their the percentage of pairs (N = 3,500) nesting breeding space. These factors suggest direct in each habitat type, arranged in order of competition for nest space on Clam Island. elevation, with bushes being the highest. In order to determine the extent of inter- When ditches are dug for mosquito control, specific interactions, I selected areas con- soil is removed and placed on the marsh. taining equal numbers of Herring and These spoil areas contained S. patens, but Laughing gulls in the S. patens contact they were higher in elevation than normal area, and recorded all aggressive interac- S. patens areas. Most birds nested in S. pa- tions, the species involved, the particular tens although 14% did nest in bushes. Had displays, and the outcome. Figure 6A shows this colony been able to nest on Clam Island the percent of total aggression (N = 560) the percentage of Laughing Gulls nesting that occurred each day and Figure 6B shows in bushes would have been substantially the percent of all aggression that was inter- higher as the bush area is three or four times specific. Although interspecific aggression greater on Clam Island. The percentage of accounted for over 45% of the interactions young surviving the storm and high tides is when Laughing Gulls first arrived, the per- indicated in the bottom graph. Over 70% of centage dropped to zero within two weeks. those young from nests in the bushes sur- The Laughing Gulls simply ceased inter- vived, whereas only 5% survived from nests acting and left. The Herring Gulls remained in S. patens. A higher percentage survived to defend territories, and subsequently laid on the higher S. patens spoil areas, attesting eggs. to the importance of these areas under ad- I made observations only in areas where verse weather conditions. Ditches created some Laughing Gulls and some Herring for mosquito control have been criticized Gulls were on territory. Since these birds GULL COMPETITION AND PREDATION 273

TABLE 1. Percent predation by Herring Gulls on Laughing Gull eggs as a function of distance from the A Herring Gull colony.

Percent Distance from at end of PeK!tTlt Herring Gull Number of Number of first week ,uat before COlOlly nests eggs after laying hatchmg

10 In 40 96 70 98 100 Ill 40 104 52 74 B 1,000 m 80 219 10 19 2,000 In 80 224 2 6

its they supplanted and chased in 85% of the encounters. Thus, with respect to con- specifics, their defense behavior during the pre-egg laying stage was similar. However, their behavior differed towards the other species (Fig. 7B). When Laughing Gulls won (only 4%), they chased the Herring Gulls. Herring Gulls won their interspecific interactions simply by supplanting the Laughing Gull intruders. In summary, Laughing Gulls attempted to defend nest sites in high S. patens areas SUPPLANT FIGHT early in the season. However, they lost most CHASE AERIAL FIGHT encounters, and were required to expend more time and energy in defense in the few FIGURE 7. Aggressive behavior of Laughing Gulls instances when they did win. (A) and Herring Gulls (C) against conspecifics, and of Herring Gulls (dashed line) and Laughing Gulls (solid Predation. It is possible that both species line) against each other (B). might engage in interspecific predation of eggs or young. I observed that Laughing Gulls did not prey on the eggs or young of could not be marked, I defined a territorial Herring Gulls whereas Herring Gulls ate as one that chased intruders from the Laughing Gull eggs and chicks. Often I area over a two-hour period. A win occurred found Laughing Gull egg shells, and legs of when one bird displaced another. When a Laughing Gull chicks with U.S. Fish and Laughing Gull was on territory it ignored Wildlife bands in Herring Gull nests. In 48% of the Herring Gull intruders, and only 1976 when substantial numbers of both 20% of the Laughing Gull intruders. Her- species nested on Clam Island, I examined ring Gulls, however, ignored 37% of the hatching rates. That year, 72% of the Her- Herring Gull intruders, and only 18% of the ring Gull eggs (N = 650) hatched and 86% Laughing Gull intruders. A Laughing Gull of the Laughing Gull eggs (N = 1,800) on territory won against Herring Gull in- hatched in widely separated sample areas. truders only 38% of the time whereas it won However, in an area of close contact only 78% of the conspecific encounters. Herring 60% of the Laughing Gull eggs (N = 200) Gulls, on the contrary, won 96% of the en- hatched whereas 85% of the Herring Gull counters with Laughing Gulls and 79% of eggs (N = 180) hatched (x2 = 17.7, df = 2, those with conspecifics. Thus, Laughing P < 0.001). To examine the predatory be- Gulls ignored more intruding Herring havior of Herring Gulls, I put out dummy Gulls, and lost when they attempted to de- nests and eggs on several areas. Significant fend their areas. Herring Gulls, however, differences occurred in the time before eggs ignored few intruders and won most of their were eaten (F = 18.0, df = 4,71, P < 0.01, encounters. When Laughing Gulls defend- least significant interval = 0.46 h). Eggs in ed territories against other species, they sup- all habitats in the Herring Gull colony re- planted or chased the intruder 88% of the mained intact for significantly longer than time (Fig. 7). A supplant involves flying to- those in non-colony grass and in Laughing ward the intruder and displacing it; where- Gull colonies. Eggs in Laughing Gull col- as a chase involves flying or walking after onies were all eaten by Herring Gulls with- the intruder. Likewise, when Herring Gulls in 1.5 h whereas those in the Herring Gull defended their territories against conspecif- colony were eaten only after 2 h (X = 7.8 ? 274 JOANNA BURGER

2.1). The mean times (*SD) before eggs roost of herons and egrets in Mexico and were eaten within the Herring Gull colony found that the largest species does not al- were: dense bushes = 10.7 + 2.2 h, edge of ways win. However, for nesting assem- dense bushes = 8.7 + 4.5 h, sparse bushes = blages of these same species (Burger 1978), 6.7 ? 2.3 h, grass = 3.5 * 1.1 h. In grassy the larger species usually does win. The areas between the two colonies the mean Cattle Egret (Bubulcus ibis), a recent invad- time before eggs disappeared was 2.1 * er of North America, is an exception as it 0.09 h, and within the Laughing Gull colony tends to win more of its encounters than the mean time was 1.3 ? 0.49 h. Laughing predicted by its small size. Cattle Egrets Gulls only nested in open grass. Observa- and Herring Gulls are strikingly similar in tions from a blind in other experiments in- that both have recently undergone a range dicated that 15 out of 16 eggs were eaten by expansion, are increasing rapidly in num- Herring Gulls. A Fish Crow (Coruus ossi- bers, win aggressive encounters against lo- fragus) ate the other egg. cal species, and threaten to displace some In 1978 I sampled Laughing Gull areas species (see Burger 1978). 10 m, 100 m and 1,000 m from Herring Gull Predation also plays a critical role in the nesting areas (Table 1). Predation rates de- relationship between Herring and Laugh- creased as a function of distance from the ing gulls. Herring Gulls are notable canni- main Herring Gull nesting area. Unfortu- bals (see Parsons 1971) as well as predators nately, Herring Gulls are now nesting over on other species (Patterson 1965, Tinbergen most of Clam Island and are within easy et al. 1967, Bourget 1973, Montevecchi strike distance of any Laughing Gull nests. 1977). Andersson (1970), however, found no Further, Herring Gulls have begun to nest measurable effects of Herring Gull preda- in the bush areas on High Bar Island, where tion on other nesting species, and Lemme- their numbers are likely to increase. tyinen (1973) reported insignificant losses of eggs to Herring Gulls. DISCUSSION Statements in the literature, however, are The competitive and predatory interactions usually vague with respect to the nature and between Laughing Gulls and Herring Gulls amount of predation in natural situations. should be placed in historical context. Lemmetyinen (1971, 1972) has examined, Direct competition seems to play the for Common Terns and Arctic Terns (Sterna most important role in the colony and nest paradisaeu), the effect of predation and the site selection problems of Laughing Gulls. defense behavior of the terns. Burger and In direct encounters with Herring Gulls, Lesser (1978) gave figures on predation Laughing Gulls were unable to successfully rates in twelve Common Tern colonies in defend nest sites. That Laughing Gulls New Jersey. Herring Gulls were the pri- compete for sites is demonstrated by their mary predators, and predation rates on eggs occurrence in the same areas of the marsh ranged from 10 to 80%. Montevecchi (1977) when they first arrive. That they lose those has provided the only quantitative data on encounters was demonstrated by direct ob- seasonal predation rates in a Laughing Gull servations of interacting pairs, and the rapid colony. Egg predation in 150 nests ranged encroachment of nesting Herring Gulls into from 20 eggs per day in mid-May to two or areas previously occupied by Laughing three a day in mid-July. He observed Her- Gulls. Their inability to successfully defend ring Gulls preying on Laughing Gull eggs nest sites is a function of temporal (see be- and chicks. The occurrence of maximum low) and size factors. Laughing Gulls are predation at different times in the breeding only one-third the size of Herring Gulls. season was discussed by Nisbet (1975). The importance of size in competitive in- In Montevecchis’ study, and in this study teractions has been noted by Morse (1974) in 1976, the colony of Laughing Gulls was who examined competition in 20 avian stud- productive and territorial birds exhibited ies and found that the larger species usually adequate mobbing defense. However, in wins. Most studies, however, have not di- I978 the number of breeding Laughing rectly examined aggressive interactions, but Gulls was severely reduced, resulting in inferred their occurrence and outcome from their inability to adequately mob and de- the degree of overlap in food resources fend their nests. Often only four or five (see Schoener 1974, Burger et al. 1979). Laughing Gulls mobbed a Herring Gull, Competition for food between Laughing and they were usually unable to deter it. A Gulls and Herring Gulls is minor (Hunt and similar effect due to low breeding numbers Hunt 1973). Burger et al. (1977) examined was noted for the Brown-hooded Gull (L. aggressive interactions in a mixed species muculipennis) in Argentina marshes (Burg- GULL CO.MPETITION AND PREDATION 275 er 1974). When gulls flew up to mob an ae- Gulls relates to their nest/colony site fidel- rial predator, a second predator would eat ity. their uncovered eggs. Thus, a colony dis- Gulls strongly tend to return to the same turbed by other factors (such as low density colony and nest site year after year (Bon- due to suboptimal habitat or competition) giorno 1970, McNicholl 1975). Philopatry seems particularly prone to predation pres- has been reported for several species of sure. gulls: Black-headed Gull (Patterson 1965), It is impossible, of course, to be sure that Black-tailed Gull (L. crussirostris; Austin these two species were not in contact at and Kuroda 1953), (L. canus; some time in the past. However, I cannot Onno 1967), Lesser Black-backed Gull evaluate this. Historically, they did not (Brown 1967), Herring Gull (Tinbergen meet until the turn of the century (Nisbet 1956) and Glaucous-winged Gull (L. glau- 1971). The causes for the rapid expansion cescens; Vermeer 1963). Although philopa- are not clearly understood, but many re- try has not been demonstrated in Laughing searchers believe that the abundance of Gulls, it is reasonable to assume that this food on garbage dumps has decreased win- tendency exists in instances where a nest ter mortality and increased reproductive was successful one year, and the site is dry success (see Drury and Kadlec 1974, Burger in the next year. Thus, individual Laughing 1977). The rapidity of the increase in Her- Gulls might return to discover that Herring ring Gulls did not allow for suitable accom- Gulls now occupy their previous nest site. modations between the species, and Laugh- Having formerly “owned” that territory, ing Gulls were adversely affected (Nisbet they might attempt to defend it before giv- 1971). The process seems to be continuing ing up and moving elsewhere. into New Jersey, with the same result. The In conclusion, Laughing Gulls seem un- new presence of Herring Gulls also affects able to adequately defend their colony and Common Terns in the northeast and New nest sites from Herring Gulls. They are thus Jersey (Burger and Lesser 1978). Similarly, forced into suboptimal, lower areas of the in Europe the recent increase in numbers marsh. The birds that remain on their tra- of Herring Gulls is adversely affecting ditional sites, now near Herring Gulls, suffer Black-headed Gulls (Kruuk 1964, Patterson high rates of predation and harassment. 1965) and Common Terns (Andersson 1970, Those that move into lower areas are sub- Greenhalgh 1974). With rapid population jected to tidal floods. Additionally, moving increases, Herring Gulls require consider- into suboptimal habitats does not insure able nesting space-that presently used by less predation when these areas are close to several other gull and tern species. Herring Gull nesting areas. Unless long- Temporal factors are also crucial in the used Laughing Gull nesting areas are pro- interactions between Laughing Gulls and tected from Herring Gulls in New Jersey, Herring Gulls. Herring Gulls arrive on the their numbers may decline dramatically as nesting colony on Clam Island at least a they have done farther north. month, and sometimes two months before the Laughing Gulls. In late February 1978, SUMMARY a few Herring Gulls landed on Clam Island Interactions between Herring and Laugh- and stood about in the snow, defending ing gulls were examined on Clam Island, areas from conspecifics. They remained on New Jersey. In the last three years, the the island only a few hours each day, but number of breeding Herring Gulls has in- nonetheless they began the process of pos- creased from 800 to 1,200 pairs, while session. By mid-March, individual gulls had Laughing Gulls have decreased from 5,000 well-defined territories. When Laughing to 500 pairs. Herring Gulls arrive on the Gulls arrived in early April, most Herring nesting areas in late February or early Gulls were firmly established on territory, March and begin egg-laying in mid-April. and many had well-constructed nests. As Laughing Gulls arrive in early or mid-April Tinbergen (1953, 1956, 1959) and others and begin egg-laying in early May. have noted, a territory owner has a greater Direct aggressive encounters between probability of winning an encounter than the two species occur in areas of overlap. does an intruder. Thus, even discounting Herring Gulls win most of these encoun- their size advantage, Herring Gulls would ters, and thus displace Laughing Gulls from probably win their encounters with the these areas. Over a two-week period Laugh- newly arrived Laughing Gulls. I believe the ing Gulls gradually abandon areas of over- persistence of the Laughing Gulls in at- lap. tempting to defend areas from Herring Herring Gulls prey on the eggs of Laugh- 276 JOANNA BURGER ing Gulls in proportion to the distances DRURY, W. H., JR. AND J. A. KADLEC. 1974. The cur- these nests are from the Herring Gull nest- rent status of the Herring Gull population in the northeastern United States. Bird-Banding 45:296- ing area. Adjacent areas suffered 100% pre- 306. dation whereas areas 1,000 m from Herring GREENHALGH, M. E. 1974. Population growth and Gulls suffered only 19% predation. Areas breeding success in a saltmarsh Common Tern col- farther from nesting Herring Gulls suffered ony. Naturalist 931: 121-127. still lower predation rates (6%) but were HAILMAN, J. P. 1963. Herring Gull extends breeding range south to North Carolina. Auk 80:375-376. vulnerable to flood and storm tides. HUNT, G. L., JR. AND M. W. HUNT. 1973. Habitat par- titioning by foraging gulls in Maine and north- ACKNOWLEDGMENTS western Euroue. Auk 90:827-839. 1 thank M. Gochfeld, F. and P. Buckley, F. Lesser and KRUUK, H. 1964. Predators and anti-predator behavior J. Shisler for discussions during the research: R. G. B. of the Black-headed Gull (Lams ridibundus L.). Brown and M. Erwin for comments on the manuscript; Behav. Suppl. 11. D. Chanda and H. Colver for field assistance: and G. LEMMETYINEN, R. 1971. Nest defence behavior of Costa and E. OMalle;’ for allowing me to dse their Common and Arctic terns and its effect on the suc- house while I worked on Clam Island. Funding was cess achieved by predators. Ornis Fenn. 48: 13-24. LEMMETYINEN, R. 1972. Nest defence behavior in the provided-_ by the Research Council of Rutgers Univer- slty and the New Jersey State Mosquito Commission. Arctic Tern Sterna paradisaea toward stuffed nest Additional logistical and moral support was provided predators on Spitsbergen. Rep. Kevo Subarctic by the Ocean County Mosquito Commission. Res. Stat. 9:28-31. LEMMETYINEN, R. 1973. Breeding success in Sterna LITERATURE CITED paradisaea Pontopp. and S. &undo L. in southern Finland. Ann. 2001. Fenn. 10:526-535. ANDERSSON, A. 1970. Food habits and predation of an MACROBERTS, M. H. AND B. R. MACROBERTS. 1972. island-breeding population of the Herring Gull The relationship between laying date and incu- Lams argentatus in southern Sweden. Ornis bation period in Herring and Lesser Black-backed Stand. 1:75-81. gulls. Ibis 114:93-97. AUSTIN, 0. L., JR. AND N. KURODA. 1953. The birds MCNICHOLL, M. K. 1975. Larid site tenacity and of Japan. Bull. Mus. Comp. 2001. 109:448452. group adherence in relation to habitat. Auk 92:98- BENT, A. C. 1921. Life histories of North American 104. gulls and terns. U.S. Natl. Mus. Bull. 113:163-175. MONTEVECCHI, W. A. 1975. Behavioral and ecological BONGIORNO, S. F. 1970. Nest-site selection by adult factors influencing the reproductive success of a Laughing Gulls (Lams at&Ala). Anim. Behav. tidal salt marsh colony of Laughing Gulls (Lams 18:434444. utricillo). Ph.D. diss.. Rutgers Universitv. New BOURGET, A. A. 1973. Relation of eiders and gulls in Brunswick, N.J. - mixed colonies in Penobscot Bay, Maine. Auk MONTEVECCHI, W. A. 1977. Predation in a salt marsh 90:809-820. Laughing Gull colonv. Auk 94:583-585. BOURN, W. S. AND C. COTTAM. 1939. The effect of MORSE,D. I?. 1974. Niche breadth as a function of lowering water levels on marsh wildlife. Trans. N. social dominance. Am. Natur. 108:818-830. Am. Wildl. Conf. 4:343-350. NISBET, I. C.T. 1971. The Laughing Gull in the north- BROWN, R. G. B. 1967. Breeding success and popu- east. Am. Birds 25:677-683. _ lation growth in a colony of Herring and Lesser NISBET, I. C. T. 1973. Terns in Massachusetts: present Black-backed gulls Lams argentatus and L. fus- numbers and historical changes. Bird-Banding cus. Ibis IO9:502-512. 44:27-55. BURGER, J, 1974. Breeding biology and ecology of the NISBET, I. C. T. 1975. Selective effects of predation Brown-hooded Gull ( maculipennis) in Ar- in a tern colony. Condor 77:221-226. gentina. Auk 91:601-613. NOBLE, G. K. AND h. WURM. 1943. The social behav- BURGER, J. 1977. Nesting behavior of Herring Gulls: ior of the Laughing Gull. Ann. N.Y. Acad. Sci. Invasion into Spatiina salt marsh areas of New 45: 179-220. Jersey. Condor 79:162-169. ONNO, S. 1967. Nesting colony of the Common Gull. BURGER, J. 1978. Competition between Cattle Egrets Orn. Kogumik 4: 114-148. and native North American herons, egrets and ib- PARNELL, J. F. AND R. R. SOOTS. 1975. Herring and ises. Condor 80: 15-23. Great Black-backed Gulls nesting in North Caro- BURGER, J., D. GLADSTONE, C. D. HAHN AND L. M. lina. Auk 92: 154-157. MILLER. 1977. Intra and interspecific aggression PARSONS, J. 1971. Cannibalism in Herring Gulls. Br. in a roost of Ciconiiformes. Biol. Behav. 2:309- Birds 64:528-537. 327. PATTERSON, I. J. 1965. Timing and spacing of broods BURGER, J. AND F. LESSER. 1978. Selection of colony in the Black-headed Gull Lams ridibundus. Ibis sites and nest sites by Common Terns Sterna hi- 107:433459. rundo in Ocean County, New Jersey. Ibis 120:433- ROGERS, C. H. 1965. Herring Gull nesting colony in 449. Barnegat Bay. Cassinia 48:38. BURGER, J. AND J. SHISLER. 1978. Nest site selection SCHOENER, T. W. 1974. Resource partitioning in eco- and competitive interactions of Herring and logical communities. Science 185:27-39. Laughing-gulls in New Jersey. Auk 95:25&266. SOUTHERN, W. E. 1970. Orientation in gulls: Effects BURGER, J., C. D. HAHN AND J. CHASE. 1979. Aggres- of distance, direction of release, and wind. Living sion in mixed species flocks of shorebirds. Anim. Bird 9:75-95. Behav. 27:459469. TINBERGEN, N. 1953. The Herring Gulls’ world. Col- DINSMORE, J. J. AND R. W. SCHREIBER. 1974. Breed- lins, London. ing and annual cycle of Laughing Gulls in Tampa TINBERGEN, N. 1956. On the functions of territory in Bay, Florida. Wilson Bull. 86:419427. gulls. Ibis 98:401-411. TINBERGEN, N. 1959. Comparative studies of the be- GULL COMPETITION AND PREDATION 277

havior of gulls (): A progress report. Be- VERMEER, K. 1970. Breeding biology of California and haviour 15: I-70. Ring-billed gulls: A study of ecological adaptation TINBERGEN, N., M. IMPEKOVEN AND D. FRANK. to the inland habitat. Can. Wild. Serv. Rep. Ser. 1967. An experiment on spacing-out as a defense 12. against predation. Behaviour 28:307-321. VERMEER, K. 1963. The breeding ecology of the Glau- Department of Biology, Livingston College, and Cen- cous-winged Gull (Larus glaucescens) on Man- ter for Coustal Studies, Busch Campus, Rutgers Uni- darte Island, B.C. Occas. Pap. B. C. Prov. Mus. L;ersity, New Brunswick, New Jersey 08903. Accepted 13: l-104. for publication 25 January 1979.

Condor,al:277 @ The Cooper Omitholngical Society 1979

RECENT PUBLICATIONS

The Warblers of America.-Ludlow Griscom, Alex- they could have been. The volume is oversize, nicely ander Sprunt, Jr., et al. Revised and updated by Edgar designed, and abundantly illustrated in color. Camer- M. Reilly, Jr. Illustrated by John Henry Dick. 1979. ons’ drawings have been planned carefully; they do Doubleday & Co., Garden City, N.Y. 302 p. $19.95. not merely depict the birds but show them in charac- The first edition of this book, issued in 1957, has long teristic postures and illustrate points mentioned in the been out of print. (For reviews of it, see Auk 75:226- text. This book is a good basic reference of its kind for 228, 1958 and Wilson Bull. 70:99-101, 1958.) The ma- serious students of birds. jor changes in the new edition involve recognition of revisions in the classification of warblers and the ad- dition of a recently discovered species. The chapters on warblers in the , by James Bond, and in Waterfowl/Ducks, Geese & Swans of the World.- , by Alexander Skutch, have been re- Frank S. Todd. 1979. Sea World Press. 399 p. $44.95. written. Other than this, the contents have not been Available: Sea World Press, 1250 Sixth Ave., San Die- much updated. The book nevertheless remains a non- go, CA 92101. The large format, handsome layout, and technical source of basic information on all the species wealth of superb color photographs in this book may in the . suggest that it is simply another pictorial extravaganza. Do not be fooled; it is a work of solid value. In words and pictures, it presents virtually all the living forms Bird Families of the World.-Illustrations by Ad of the Anseriformes, including screamers. The Order Cameron; Consultant Editor, C. J. 0. Harrison. 1978. as a whole is introduced, after which each of the Harry N. Abrams, Inc., New York. 264 p. $25.00. The subgroups is treated. Closing chapters discuss water- class of birds passes here in review, in a book of similar fowl in relation to mankind-in captivity and in the scope to those by Gilliard (1958) and Austin and Singer wild. In his Foreword, Jean Delacour says of the text, (1961). All living families and several extinct ones are “It is . of high quality, accurate and to the point, and taken up in turn. In clearly organized accounts, each it contains much new information about the behavior family is characterized in terms of its appearance, dis- of a number of species.” One appendix tabulates basic tribution, habits, behavior, economic importance, and data on all the species and of waterfowl. system&es. The authors are some 40 ornithologists, Another gives well-founded advice about photograph- but since half of them are British many families have ing these birds. Glossary, selected bibliography, and been written up by people who have had little field index. This book is less useful than Johnsgards’ (no- experience with them. Consequently, while the ac- ticed in Condor 81:27, 1979) as a technical reference counts are informative and mostly accurate, they con- but it is unequalled for showing the birds und telling tain needless errors and are sometimes less solid than their natural history.