Help with correlated subquery please

SQL++
2

N1QL query not right due to USE KEYS t1,t2 always same it gives same row as t1.
As you want each BirdId you want the record that has latest dateTime

SELECT  doc.dateTime, doc.birdId, doc.island
FROM `bird` AS t1
WHERE t1.docType = 'Record' AND t1.birdId IS NOT NULL
GROUP BY t1.birdId
LETTING doc = MAX([t1.dateTime,{t1.dateTime, t1.birdId, t1.island}])[1]
ORDER BY birdId;

OR

SELECT  t1.birdId,  doc[0] AS dateTime, doc[1] AS island
FROM `bird` AS t1
WHERE t1.docType = 'Record' AND t1.birdId IS NOT NULL
GROUP BY t1.birdId
LETTING doc = MAX([t1.dateTime, t1.island])
ORDER BY birdId;

CREATE INDEX ix1 ON `bird`(birdId, dateTime,island) WHERE docType = "Record";

Read Select non-group by fields using sql query for understanding the technique.