Data from: Females are larger and less detected than males but experience similar annual survival in the lek-displaying Eleothreptus anomalus (Sickle-winged Nightjar)

Name: Data from: Females are larger and less detected than males but experience similar annual survival in the lek-displaying Eleothreptus anomalus (Sickle-winged Nightjar)
License: https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
Keywords: body size

Datos de investigación

Data from: Females are larger and less detected than males but experience similar annual survival in the lek-displaying Eleothreptus anomalus (Sickle-winged Nightjar)

Autores: Cockle, Kristina Louise Icon

; Fariña, Nestor; Villalba, Olga; Kopuchian, Cecilia Icon

; Kraemer, Simón; Bodrati, Alejandro; Pagano, Luis; Pietrek, Alejandro Gerardo Icon

Publicador: Consejo Nacional de Investigaciones Científicas y Técnicas

Fecha de depósito: 23/04/2026

Fecha de recolección: 01/09/2012-30/04/2025

Clasificación temática:

Zoología, Ornitología, Entomología, Etología

Resumen

We examined age- and sex- specific variation in body size, apparent annual survival, and recapture probability using morphometric measurements, molecular sexing, logistic regression, and Cormack-Jolly-Seber models on 1006 captures of 370 Eleothreptus anomalus (Sickle-winged Nightjars) in northeastern Argentina (2012–2025). Adult females were larger than males in all measurements, with a dimorphism of 45% in length of secondary feathers, 30% in weight, 16% in tail length, and 10% in total length. Sexual size dimorphism (females larger than males) also occurred in juveniles, such that we were able to accurately determine the sex of juveniles by their measurements, especially the length of their secondaries. The best Cormack-Jolly-Seber models included age-specific survival (adults: 0.67 annually, CI: 0.6–0.73; juveniles: 0.58, 0.48-0.68) and a sex-specific capture probability for adults (females: 0.19, 0.11–0.31; males: 0.64, 0.53–0.74), highlighting the need to account for intraspecific variation in avian demographic parameters. We propose that the larger size of females, not previously recorded in any nightjar species, is related to sexual or social selection for the males’ extraordinary ‘sickle-shaped’ wings. The data and code are in two parts: (1) morphometric measurements and logistic regression in a Monte Carlo Cross Validation framework; (2) Cormack-Jolly-Seber models of sex-specific adult and juvenile survival.

Tabla de contenidos

Description of the data and file structure Captures and measurements of Sickle-winged Nightjar at Reserva Natural Rincón de Santa María and a few other sites in northeastern Argentina, 2012-2025. The code and files come in two parts: (1) Morphometry, which includes the R script Morphometry.R and the two files Eleothreptus_measurements.csv and Eleothreptus months.csv, including captures at Reserva Natural Rincón de Santa María and other sites. (2) Survival, which includes the R script CJS_survival.R and the two files Eleothreptus_adult_capture_histories.xlsx and Eleothreptus_juvenile_capture_histories.xlsx. You can run these two sections independently from one another, although they are based on the same raw data. The morphometric sexing results of Part 1 were incorporated manually into the datasets for Part 2. Files and variables File: Morphometry.R Description: Code for morphometry analysis of Eleothreptus anomalus, including sex determination by logistic regression using Monte Carlo Cross Validation in a for loop. Author: Kristina Cockle. File: Eleothreptus_measurements.csv Description: Morphometric measurements of Eleothreptus anomalus for input to Morphometry.R code. NA indicates missing values. Nestor Fariña took measurements on 86% of captures; Luis Pagano took 8%; Kristina Cockle and seven other collaborators took the remaining 6%. Variables ID_Final = aluminum leg band number (unique to each individual bird) Localidad = Locality (RNRSM = Reserva Natural Rincón de Santa María, Corrientes, Argentina; CSJ = Campo San Juan, Misiones, Argentina; PPSanAntonio = Parque Provincial San Antonio, Corrientes, Argentina; ResDonLuis = Reserva Don Luis, Corrientes, Argentina) codigo_salida = date (night) of capture (YYYY-MM-DD). For birds captured after midnight, codigo_salida is the date of the previous day, so that all birds captured in the same night have the same codigo_salida. Year = year of capture Sexo_plum = sex by plumage (M = male, H = Female, from the Spanish [hembra]). Birds were sexed primarily by Nestor Fariña and Luis Pagano based on plumage characteristics in the field. Juvenile birds could not be sexed by plumage, but we assigned their sex retroactively if they were recaptured in adult plumage. Sexado_Mol = sex by molecular sexing (M = male, H = Female, from the Spanish [hembra]). Molecular sexing was performed by Cecilia Kopuchian and Simón Kraemer on a subset of juveniles. Sexo_final = final sex (M = male, H = Female, from the Spanish [hembra]), as determined by plumage and/or molecular sexing. Edad_final = age (A = Adult, I = intermediate, J = Juvenile, Pichón = nestling or recent fledgling [from Spanish]). Birds were aged by plumage or in some cases based on previous captures. Intermediates are approximately 1-year old birds in plumage that is transitioning from Juvenile to Adult. Peso = weight in grams [from Spanish], measured with a spring balance (1 g). Ala = wing chord in mm [from Spanish], measured with a wing rule. Secundarias = length of secondary feathers in mm [from Spanish]. As described in Cockle et al. (in press, Ornithology): "Beginning in October 2018, we measured the length of the secondaries by extending the right wing, hooking the wing rule on the radius (leading edge of the wing), and measuring to the tip of the 4th secondary (Fig. S2). Although this measurement is not typical in ornithology, it gave us repeatable results within individual birds on different dates (Table S1)." Cola = tail length in mm [from Spanish]. Measured using a ruler. Tarso = tarsus length in mm to final leg scale before toes divide [from Spanish]. This was not the measurement we used in the paper, as it was inconsistent, but it is included here because the Morphometry.R code assesses its usefulness. Tarso_completo = complete tarsus length in mm to between toes [from Spanish]. From Cockle et al. (in press, Ornithology): "We used a caliper (0.1 mm) to measure the tarsus as follows: we rested the movable caliper jaw on the distal tibial epiphysis (bony protrusion posterior to the tibiotarsal joint), and the static jaw between the 2nd and 3rd toes, which we kept flexed toward the 1st toe (Fig. S2)." Largo_total = total length from tip of beak to tip of tail [from Spanish]. From Cockle et al. (in press, Ornithology: "Beginning in October 2021, we measured the total length of each individual (from the tip of the bill to the tip of the tail) by lying them on their back on a wing rule (1 mm) and holding the tip of the bill against the top of the ruler (Fig. S2)." File: Eleothreptus_months.csv Description: Captures by month of the year, to assess intra-annual variation. NA indicates missing values. Variables ID_Final = aluminum leg band number (unique to each individual bird) Localidad = Locality (RNRSM = Reserva Natural Rincón de Santa María, Corrientes, Argentina; CSJ = Campo San Juan, Misiones, Argentina; PPSanAntonio = Parque Provincial San Antonio, Corrientes, Argentina; ResDonLuis = Reserva Don Luis

Métodos

Field, lab, and statistical analysis methods are described in Cockle et al. 2026. Females are larger and less detected than males but experience similar annual survival in the lek-displaying Eleothreptus anomalus (Sickle-winged Nightjar). Ornithology. Additional details are provided in the supplementary material to that article.

Palabras clave: body size, Caprimulgidae, Cormack-Jolly-Seber, nightjar, reverse sexual size dimorphism, sex-specific survival

Alcance geográfico

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Identificador del recurso

URI: http://hdl.handle.net/11336/285552

Colecciones

Datos de Investigación(CECOAL)
Datos de Investigación de CENTRO DE ECOLOGIA APLICADA DEL LITORAL (I)

Datos de Investigación(CICYTTP)
Datos de Investigación de CENTRO DE INV.CIENT.Y TRANSFERENCIA TEC A LA PROD

Datos de Investigación(IBIGEO)
Datos de Investigación de INST.DE BIO Y GEOCIENCIAS DEL NOA

Citación

Cockle, Kristina Louise; Fariña, Nestor; Villalba, Olga; Kopuchian, Cecilia; Kraemer, Simón; Bodrati, Alejandro; Pagano, Luis; Pietrek, Alejandro Gerardo; (2026): Data from: Females are larger and less detected than males but experience similar annual survival in the lek-displaying Eleothreptus anomalus (Sickle-winged Nightjar). Consejo Nacional de Investigaciones Científicas y Técnicas. (dataset). http://hdl.handle.net/11336/285552

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