How Do Female Red-winged Blackbirds Allocate Food within Broods?

Abstract

Nestlingscommunicate with parents via begging, but what does begging signal and how do parents . .^ajloeate food to their nestlings? We tested the signal-of-need (SoN) and signal-of-quality (SoQ) hypotheses for ., 'j ' '^iiè'stling b'eg^ñg in the Redrwinged B\ack.'èir'a{Agelaiusphoeniceus) by attempting to determine whether begging '•^r.'r' H-:.f'. f.fAneg|tivèlyî{S01Î')'oi''positively (SoQ) condition dependent, and by attempting to identify the attributes of nest-'' lings'that parents use'to allocate food within broods. We quantified begging by its mean intensity (scale 0-7) and mean duration and parental allocation by the number of times each nestling was fed. We found that the intensity and duration of begging were not correlated with nestlings' size (estimated by body mass and tarsus length), condition (estimated from the residual of mass regressed on tarsus length), age, sex, or testosterone concentration, so begging did not appear to be negatively or positively condition dependent. A generalized linear model showed that mean intensity of begging, body condition, and log testosterone concentration were significant predictors of the number of feedings. These results are consistent with parents using begging intensity and nestling quality, but not long-term need, to allocate food within broods.¿Cómo Asignan los Alimentos entre las Crías las Hembras de Agelaius phoeniceus?Resumen. Los pichones mendigan para comunicarse con sus padres, pero ¿qué señal representa esto y cómo los padres asignan los alimentos a sus pichones? Evaluamos las hipótesis de la señal de necesidad (SdN) y la señal de calidad (SdC) para pichones de Agelaius phoeniceus que mendigan intentando determinar si la mendicidad depende negativa (SdN) o positivamente (SdC) de la condición, e intentando identificar los atributos de los pichones que usan los padres para asignar los alimentos entre las crias. Cuantificamos la mendicidad de acuerdo a su intensidad media (escala 0-7) y duración media, y la asignación de los padres con el número de veces que cada pichón fue alimentado. Encontramos que la intensidad y la duración de la mendicidad no estuvieron correlacionados con el tamaño del pichón (estimado por la masa corporal y el largo del tarso), la condición (estimado a partir del residuo de la regresión de la masa con el largo del tarso), la edad, el sexo o la concentración de testosterona, por lo que la mendicidad no parece depender positiva o negativamente de la condición. Un modelo lineal generalizado mostró que la intensidad media de la mendicidad, la condición del cuerpo y la concentración logarítmica de la testosterona predijeron significativamente el número de provisiones de alimento. Estos resultados son consistentes con la noción de que los padres usan la intensidad de mendicidad y la calidad del pichón, pero no la necesidad de largo plazo, para asignar los alimentos entre las crias.

Transforming mentorship in STEM by training scientists to be better leaders

“…First, they provide direction, set standards for work in their field, and help mentees develop and troubleshoot their research projects (Vilkinas, 2008). Second, the advisor is the principal gateway for mentees into their departmental and discipline communities, and therefore needs to advocate for mentees and help them establish connections with other colleagues (Bair, Grant Haworth, & Sandfort, 2004;Barnes & Austin, 2009;Krauss & Yasukawa, 2013;Lovitts, 2001;Lyons et al, 1990). Third, the advisor must identify when students are struggling and help them find solutions (Barnes, Williams, & Stassen, 2012;O'Meara & Braskamp, 2005).…”

Eavesdropping and cue denial in avian acoustic signals

“…Experiments in which begging calls are played from speakers placed near nests show that in most cases parents respond to augmented calling by increasing their rate of feeding visits to the brood (Muller & Smith 1978, Bengtsson & Ryden 1983, Burford et al 1998, Price 1998, Kilner et all 1999, Tarwater et al 2009, but see Clark & Lee 1998). A variety of evidence suggests that parents are also influenced by begging intensity in allocating feedings among the young within broods (Smith & Montgomerie 1991, Kacelnik et al 1995, Rosivall et al 2005, Tanner et al 2008, Krauss & Yasukawa 2013, but this evidence is compatible with parents responding to visual rather than auditory components of begging. To our knowledge, only one study has experimentally isolated an effect of auditory signals on allocation within broods.…”

A diagnosis model of parental care: How parents optimize their provisioning strategy in brood reduction?

“…It is common that parents have given their provisioning priority to core offspring than to marginal ones in order to enhance their reproductive fitness ( Jeon 2008; Forbes and Wiebe 2010 ). However, marginal offspring are of lower competitive than core offspring just because they are younger ( Mock and Forbes 1995 ; Forbes 1999 ; Krist 2011 ), not because they have lower quality ( Parker et al 2002 ; Krauss and Yasukawa 2013 ) than the latter. If an additional unit of resource has been allocated to a marginal offspring, it can result in a higher reproductive return to parents than what is allocated to a core offspring ( Godfray 1991; Krauss and Yasukawa 2013 ).…”

“…However, marginal offspring are of lower competitive than core offspring just because they are younger ( Mock and Forbes 1995 ; Forbes 1999 ; Krist 2011 ), not because they have lower quality ( Parker et al 2002 ; Krauss and Yasukawa 2013 ) than the latter. If an additional unit of resource has been allocated to a marginal offspring, it can result in a higher reproductive return to parents than what is allocated to a core offspring ( Godfray 1991; Krauss and Yasukawa 2013 ). Moreover, in some altricial birds, marginal nestlings can grow faster than their core brood mates, although they are smaller at the beginning of the nestling period because of their younger age ( Da et al 2018 ).…”