Second successful breeding of Australian gull-billed tern (Gelochelidon nilotica macrotarsa) in New Zealand

BackgroundCoastal saltpans are a common supratidal human-modified wetland habitat found within many coastal landscape mosaics. Commercial salt production and aquaculture practices often result in the creation of exposed coastal substrates that could provide suitable breeding habitat for waterbird populations; however, few studies have quantified waterbird breeding success in these artificial wetlands.MethodsHere we examine the nesting behavior of the Gull-billed tern (Gelochelidon nilotica) breeding in the Nanpu coastal saltpans of Bohai Bay, Yellow Sea, China over three consecutive nesting seasons (2017–2019) by using nest survival model in Program MARK.ResultsThe results revealed that nest survival of Gull-billed terns in coastal saltpans (0.697) was higher than previously published estimates from other regions, with an estimated daily survival rate (DSR) of 0.982 ± 0.001 (±95% CI). High nest survival was mainly attributed to low levels of human disturbances and low predation rates, while exposure to strong winds, flooding and silting were the main factors causing nest failure. Model-averaged estimates revealed that eggs laid in nests located on ‘habitat islands’ with feather or clam shell substrates were most likely to hatch. Initiation date, nest age, clutch size and quadratic effects of nearest-neighbor distance, nearest distance to road and nearest distance to water were all significant predictors of nest success, but the nest survival declined overall from 2017 to 2019 due to the degradation and loss of breeding habitat anthropogenically caused by rising water levels.DiscussionCoastal saltpans represent an alternative breeding habitat for the Gull-billed tern populations in Bohai Bay, but conservation management should prioritize flood prevention to improve the extent and quality of breeding habitat, concurrent with efforts to create further ‘habitat islands’ with suitable nesting substrate.

The use of drones in the study of waterbird breeding biology has received considerable attention in the last years, but very few studies were made along the Mediterranean. We studied habitat selection and breeding success of the Gull-billed Tern Gelochelidon nilotica in two colonies inside fish farms along the Italian Adriatic coastline, using a small, commercial drone. Both colonies were located on small islets surrounded by very shallow water and clayey bottoms, thus being difficult to access. Compared with availability, the Gull-billed Terns selected quadrats higher above the water level, with a higher vegetation cover, which lay farther from the water edge, contain less water, and which are more frequently located in the center of the islands. 147 of 178 clutches (mean clutch size ± SD: 2.61 ± 0.58) hatched 383 chicks (82.5%; 2.15 ± 1.09 chicks per nest), with large differences between the two colonies. Hatching success was 95.0% and 69.1%; the most common cause of egg loss was flooding (97.0%). Nest attendance could easily be ascertained by 30-m above ground level drone-derived imagery. The use of a drone allowed the study of some aspects of the breeding biology of the Gull Billed Tern in two breeding sites where the traditional field approach, i.e. researchers reaching the sites by boat, would have been very difficult, causing unavoidable and prolonged disturbance to the nesting adults.

Measuring the productivity of gulls Laridae and terns Sternidae is often difficult, due to natural obstacles of site access and the need to avoid disturbing nesting birds. Drones are increasingly being used for conservational and ecological applications and their use seems to overcome these problems, but data are still scarce on their use to assess breeding success. Our objective was to compare the effectiveness, time consumption, and safety for birds of drone-conducted monitoring of nest-specific hatching success with usual ground surveys of two species of gulls, including Slender-billed Gulls Chroicocephalus genei and Mediterranean Gulls Larus melanocephalus, and two species of terns, including Gull-billed Terns Gelochelidon nilotica and Sandwich Terns Thalasseus sandvicensis, breeding in the Adriatic wetlands of northeast Italy. We studied 400 nests (100 per species distributed in eight plots, each with 50 nests) and found no significant difference between the two methods in determining the number of eggs either laid or hatched per nest for all four focal species. The average coefficient of agreement between methods was high (kappa > 0.80 for all comparisons). The mean time spent determining the hatching success of 50 clutches with a drone (263 sec per plot) was significantly less than with ground surveys (760 sec per plot). There were no apparent negative effects of drone flights on nesting pairs, clutches, or young. Our results suggest that drones allow effective, rapid, and safe measurement of seabird breeding success in coastal areas.

This is the 31st annual report from the Norwegian Rarities Committee (NSKF). The majority of records treated here are from 2006, but some older records are also included. The Norwegian rarities committee follow advises given by the Taxonomic Advisory Committee (TAC) of the Association of European Record and Rarities Committees (AERC) on issues concerning taxonomy and nomenclature. The systematic list of accepted records is set out in the following system: (1) The bird’s Norwegian name, (2) scientific name, (3) the numbers in brackets, e.g. (2, 30/32, 1), refers respectively to the ( i ) total number of records/total number of individuals up to and including 1974, ( ii ) total number of records/total number of individuals from 1975 (the foundation year of NSKF), except ( iii ) records/individuals in 2006, (4) any breeding, (5) year, (6) county, (7) number of individuals, age (1K = first calendar year etc.), sex (if known) and sometimes circumstances («rm» means that the bird was ringed), (8) site and municipality, (9) date, (10) * indicates if the record was complemented by positive evidence, and type of the evidence (F = photo, V = video-recorded, L = tape-recorded, DNA = DNA-analysis, D = found dead), (11) observers’ names in brackets, main observer(s) is specified first and emphasized with *, (12) roughly gives the species’ distribution and (13) comments concerning the records. Species, subspecies and hybrids new to the Norwegian list: With 245 accepted records presented in this report, 2006 was another good year for rare birds in Norway. A total of 42 accepted records from previous years complete the status of rare birds on the Norwegian list. There are five records presented that have been shelved. Also presented are 26 records that for some reason have not been accepted. All previous records of Booted Warbler Hippolais caligata ssp. and Bonelli’s Warbler Phylloscopus bonelli ssp. have been reassessed following the recent split of these two species. The two formerly accepted records of Snow Bunting Plectrophenax nivalis of the subspecies vlasowae have also been reassessed based on new knowledge on the variation within the nominate subspecies. Three new species to the Norwegian category A list are presented in this report. This brings the official Norwegian list to 477 species. Included in this list are accepted records in category A-C. The new species in 2006 were Masked Shrike Lanius nubicus (Utsira, Rogaland 2nd to 15 th October) and Blackpoll Warbler Dendroica striata (Reve, Rogaland 2nd to 12th November). In addition the first two Sykes’s Warblers Hippolais rama (Forus, Rogaland 11th September 1983 and Monstermyr, Vest-Agder 20th September 1997) were accepted during the reassessment of older records. A Red-necked Grebe Podiceps grisegena collected at Traena, Nordland 28th January 1949 has been accepted as the first Norwegian record of the holboellii subspecies. Two records of hybrid Blue-winged Teal Anas discors x Northern Shoveler A. clypeata (Aheim, More og Romsdal 7th – 9th June 2003 and Lista fyr, Vest-Agder 31 st July – 5th August 2006) have also been accepted as the national first and second records. General trends: Record numbers for Norway was recorded for the following species during 2006: Great Bittern Botaurus stellaris (eight records), Black Kite Milvus migrans (nine records), Mediterranean Gull Larus melanocephalus (ten records), Citrine Wagtail Motacilla citreola (nine records) and Lesser Grey Shrike Lanius minor (three records). Also, 2006 saw the highest number (six records of eleven birds) for Corn Bunting in recent times, including the first successful breeding since 1939. Six records involving ten birds of Arctic Redpoll Carduelis hornemanni of the nominate subspecies was also an all time high. Also published here are the 4th & 5th Egyptian Goose Alopochen aegyptiaca for Norway, 4 th American Black Duck Anas rubripes , 3rd Piedbilled Grebe Podilymbus podiceps , 2nd Little Shearwater Puffinus [assimilis] baroli , 3rd Swinhoe’s Storm-petrel Oceanodroma monorhis , 5th Collared Pratincole Glareola pratincola , 4 th American Golden Plover Pluvialis dominica , 8th & 9th Bonaparte’s Gull Larus philadelphia , 4th, 8th & 9th Yellow-legged Gull Larus michahellis , 10th & 11th Caspian Gull Larus cachinnans , 7 th Gull-billed Tern Sterna nilotica , 4th Isabelline Wheatear Oenanthe isabellina , 2nd Eastern Orphean Warbler Sylvia crassirostris and 2 nd Black-faced Bunting Emberiza spodocephala (cat. D).