Do females of Whiskered Tern Chlidonias hybrida renest after offspring desertion?

Figures & data

Figure 1. Distribution of breeding sites of the Whiskered Tern Chlidonias hybrida in Upper Vistula River Valley, Southern Poland, 2015–2018. A – carp pond complexes with breeding colonies, A1 – carp pond complexes where breeding birds were marked.

Table I. Desertion of Whiskered Tern Chlidonias hybrida females during the chick-rearing period, eastern part of the Upper Vistula River Valley.

Year	Nests	No. of nests with female desertion	Number of colonies studied
2015	32	16 (50%)	3
2016	25	13 (52%)	2
2017	16	5 (31%)	2
2018	18	7 (39%)	2
Total	91	41 (45%)	9

Table II. Cases of Whiskered Tern Chlidonias hybrida females involved in some kind of breeding activity after desertion, eastern part of the Upper Vistula River Valley, 2015–2018.

Female ID	Remating and renesting/ participating in courtship activity	First-clutch laying date	Desertion date, age of chicks at the time of desertion	Second-clutch laying date	No. of days between desertion and second clutch being laid or desertion and observation (birds participating in courtship activity)	No. of days between first and second clutches being laid	Distance between first and second breeding sites (km)
YN17926	Remating and renesting	07/06/2015	07/07/2015, 10 days	24/07/2015	17	47	1.6
YN22290	Remating and renesting	26/05/2017	30/06/2017, 7 days	Unknown, female was found incubating on 24/07/2017	max. 24 days	max. 59	1.1
YN17939	Participating in courtship activity	12/06/2015	18/06/2015, 17 days	N/A	36	N/A	0.4
YN20357	Participating in courtship activity	8/06/2016	09/07/2016 8 days	N/A	5	N/A	0.4
YN22289	Participating in courtship activity	29/05/2017	25/06/2017 6 days	N/A	18	N/A	5.3
YN22298	Participating in courtship activity	4/06/2017	05/07/2017 8 days	N/A	3 and 5	N/A	7

Table III. Whiskered Tern Chlidonias hybrida females that deserted and renested after brood failure, eastern part of the Upper Vistula River Valley, 2015–2018. *Female remated with the same male.

Female ID	First-clutch laying date	Desertion date, brood failure date	Second-clutch laying date	No. of days between brood failure and second clutch being laid	No. of days between first and second clutches being laid	Distance between first and second breeding sites (km)
YN17943	08/06/2015	06/07/2015 09/07/2015	22/07/2015	13	44	0.5
YN20314*	30/05/2016	26/06/2016 03/07/2016	16/07/2016	13	47	4.3
YN20345	07/06/2016	09/07/2016 12/07/2016	19/07/2016	7	42	0.4