NEST ATTENDANCE OF PARENT BIRDS IN THE PAINTED SNIPE (ROSTRATULA BENGHALENSIS) SHIGEMOTO KOMEDA Laboratoryof AnimalSociology, Faculty of Science,Osaka City University, Sugimoto,Sumiyoshi-ku, Osaka 558, Japan ABSTRACT.--Iobserved 15 pairs of Painted Snipes (Rostratulabenghalensis) in Japanfor 24-h periods in order to compare the nest attendance behavior of males and females and to documentchanges in their behavior during the laying period. From a few days before the laying of the first egg until the day the secondegg was laid, the male and female consorted with eachother (stayedwithin 5 m of each other) more than 90% of the observationtime. They visited the nest repeatedlyon the first and seconddays of laying. On the third day, the consortingratio decreasedto 58.5%, and the male typically started to incubate. He continuedto incubate that night. After laying the third egg, the female usually did not visit the nest exceptto lay the fourth and last egg. The male continuedincubation, and the female met her mate only when she laid the last egg. The absenceof female incubationand the early termination of consortingbehavior are consistentwith the possibility that Painted Snipe femalesare polyandrous.Received 12 January1982, accepted4 October1982. AMONG the polyandrous charadriiform qualis), and cudweed (Gnaphaliumaffine), grew species, comprehensive studies of pair-bond sparselyin theseabandoned fields. The water depth maintenancehave been conductedon only four in this area varied from 0 to 15 cm. species, the Northern Jacana(Jacana spinosa; The main study was conducted in Toyo City, northwestern Shikoku Island, Japan (133ø03'E, Jenni and Collier 1972, Jenni and Betts 1978), 33ø57'N),from March to August1979 (excluding May) the SpottedSandpiper (Actitisrnacularia; Hays and from June to July 1980 (Toyo area). This 40-ha 1972, Oring and Knudson 1972, Maxson and study area of reclaimedland facesthe JapaneseIn- Oring 1980),the Red-neckedPhalarope (Phal- land Sea. A quarter of the area was used as paddy aropuslobatus; Hild6n and Vuolanto 1972),and fields, and the rest was marshy grasslandthat was the Red Phalarope(Phalaropus fulicaria; Scha- plowed onceor twice a year, usuallyin Juneand July. mel and Tracy 1977).Although a detailedstudy The study area was traversedby six parallel roads of the Painted Snipe (Rostratulabenghalensis) 200m apartand by anotherroad that intersected them has not been conducted, sex role reversal and at right angles.This poorly drained areawas always an apparentlyunbalanced sex ratio suggestthe covered with water. Until it was plowed, dense reed (Phragmitescommunis) or bulrush (Scirpusplanicul- possibility of polyandry in this species(Beven mis) grew there every year. After it was plowed, the 1913, Baker 1935, Lack 1968, Hays 1972, Oring grassesgrew only patchilyor sparselybefore Sep- and Knudson 1972,Jenni 1974).The objectives tember. The Toyo area is about 300 km west of the of this study were (1) to compare the nest at- Biwa area. tendance of male and female Painted Snipes, Most data for the field study were obtained by con- (2) to measurethe amount of time the members tinuous observations. Observations that started after of the pair spend together (consortingratio) 1800 are identified as "nocturnal observations" and during laying and incubationperiods, and (3) were made with the aid of a flashlight.Behavior was to considerthe evidence for polyandry. observedwith binoculars(9x) and a spotting scope (15x). Behavioral actswere recorded in seconds,and the data were later converted to minutes for calcu- STUDY AREAS AND METHODS lations. Of 27 birds observed, 4 males and 2 females Field observations were made in two areas. The were marked with neck bands. Because no other birds preliminary study was done in Chuzu Town, south- of the same sexes as the banded individuals were east of Lake Biwa, central Japan(136ø02'E, 35ø08'N), observedentering their nests, any male or female from May to June1978 (Biwa area). Nest observations who entered a nest was consideredthe progenitor of were conductedin 20-ha abandonedfields among the eggsin the nest. paddy fields at an elevation of about 85 m. Marshy All observationsreported here were made at nests plants, mainly buttercup(Ranunculus quelpaertensis), with four eggs.The four eggswere laid on consec- bitter cress(Cardamine lyrata), foxtail (Alopecurusae- utive days,and the daysof layingwere identifiedas 48 The Auk 100: 48-55. January1983 January1983] NestAttendance in Painted Snipes 49 T^BLE1. The lengthof visitsto the nestduring the layingperiod (minutes + SD).Numbers in parentheses indicate nocturnal visits. Day I Day 2 Day 3 Day 4 Female Lengthof egg-layingvisits 35.5 + 17.5 62.3 + 33.4 32.8 + 7.4 15.9 + 1.9 Number of egg-layingvisits 2 4 5 6 Length of other visits 3.6 + 3.7 6.1 + 5.2 5.7 + 5.3 I -- Number of other visits 43 50 36 I Male Length of visits 3.6 + 8.0 8.0 + 12.8 22.6 + 31.7 43.4 + 52.8 (21.6 + 15.1) (36.1 + 10.2) Percentageof stayslonger than 2.0 6.8 26.2 46.8 30 min (35.3) (76.9) Number of visits 99 85 92 47 (17) (13) Number of nests 4 7 9 8 (1) (1) day 1, day 2, and so on. Thesefour dayscomprise During the laying period, a female laid an egg the layingperiod. A spanof a few daysbefore day every morning between 0700 and 1100(Fig. 1). I is referred to as the prelaying period. The incu- She stayedon the nestfar longerwhen coming bationperiod extends from the day afterday 4 until to lay an eggthan at other times(Table 1). The hatching. female was on the nest for a much shorter du- The percentageof time during which the two ration when she laid the fourth egg (2 = 15.7 membersof a pair stayedwithin 5 m of eachother was termedthe consortingratio. Consortingbehav- min) than when she laid the earlier eggs (2 = ior was studiedat the Toyo areafor a total of 17 days 44.0 min). All other visits to the nest by the (162.0h). Other observationswere madeat both the female during the laying period were much Toyo and Biwa areas. shorter(2 = 5.1 min); 88.5% of thesevisits were Nest-related behavior in the Biwa area was ob- less than 10 min. served from blinds about 10 m from the nests. Four On four additional days when the 1st, 2nd, nestswere observedfor a total of 17 days (190.8 h). or 3rd eggs were laid but egg laying was not Observationswere made at the Biwa area during two observed,females stayed on the nest for 39, 42, nights(22.6 h) of the incubationperiod. All diurnal 46, and 47 min between 0800 and 1210 (Fig. 1; observationsat the Toyoarea were made from a blind 22 June 1979, 21 June 1978, 3 June 1978, and 12 on a carroof 1.5 m abovethe ground.By driving the car alongthe roads,I was able to follow the birds June 1979, respectively).These four stayswere whenthey left their nests.Nine pairswere observed the only long stay on thosedays. It is assumed at the Toyoarea for a total of 36 days(368.7 h) Two that egg laying occurredduring theselong vis- of thesenine pairsabandoned their nestsduring the its. Egg laying was not seen at two nests on layingperiod, so the datafrom thesenests were ex- day 4, but the females entered the nests only cluded from the results(total 7 days).Two nestswere once, and it is assumed that they laid during observeda total of four nights (47.0 h) during the thesevisits (Fig. 1; 30 March 1979 and 21 July layingperiod. Activity at night at the Toyoarea was 1979). observed at intervals of 1 min from about 20 m when Nestvisitation on eachlaying day.•On day 1, a flashlightwas switched on for about5 s and off for about 55 s. both sexesentered the nest frequently during the morning (Fig. 1), but they often left it for RESULTS a long time during the afternoon. They re- turned to the nest in the evening. The male Clutch size and time of laying.•Of 33 nests stayedabout the samelength of time (Table 1) found, 2 had 3-egg clutches,30 held 4 eggs, and enteredthe nest about as frequentlyas the and only 1 held 5 eggs.Accordingly, the nor- female did. No observations were made on the mal clutch size in this speciesis consideredto night of day 1. be four. On day 2, the duration of diurnal visits in- The time of laying was recorded 17 times. creased but the number of visits decreased 50 $HIGEMOTOKOMEDA [Auk,Vol. 100 TIME OF DAY DAYTIME ACTIVITY 6 9 12 15 18 DAY DATE NEST , I 12• JUN '79'78 62 2 AUG ' 79 9 9 .N.JG '79 I0 4JUN '78 2 15 JUN '78 :• 20 JUN '78 4 28 MAR ' 79 5 13 JUN ' 79 6 22 JUN '79 7 3' AUG ' 79 9 I5 MAY '78 I 5 JUN '78 2 16 JUN '78 3 21 JUN '78 4 29 MAR '79 5 I 4 JUN ' 79 6 23, JUN '79 7 4 AUG '79 9 I I AUG '79 I I 16MAY '78 I 6 JUN '78 :• 17 JUN '78 '• 22 JUN '78 4 :30 MAR '79 5 2[ JUL '79 8 5 AUG '79 9 12 AUG '79 I I NIGHTTIME ACTIVITY 18 21 0 3 6 DAY DATE NEST 2 i8-19 JUN'80 14 2 24-25JUL '80 15 • 25-26JUL '80 15 4 26-27JUL '80 15 Fig. 1. Activity during laying period. Male is shown in upper and female in lower belt of each pair. Blackband shows time spenton nestand shadedband out of nest.Small dot shows the time of egglaying. Day 1 is the first day of egg laying and day 4 the last day.