Noninvasive unmanned aerial vehicle provides estimates of the energetic cost of reproduction in humpback whales

By F. Christiansen, A. Dujon, K. Sprogis, J. Arnould, L. Bejder. 2016

253 citations recorded by the source corpus.

An animal's body condition will affect its survival and reproductive success, which influences population dynamics. Despite its importance, relatively little is known about the body condition of large whales and its relationship to reproduction. We assessed the body condition of humpback whales (Megaptera novaeangliae) at a breeding/resting ground from aerial photographs recorded using an unmanned aerial vehicle (UAV). Photogrammetry methods were used to measure the surface area of individual whales, which was used as an index for body condition. Repeated measurements of the same individuals were not possible; hence, this study represents a cross-sectional sample of the population. Intraseasonal changes in the body condition of four reproductive classes (calves, immature, mature, and lactating) were investigated to infer the relative energetic cost that each class faces during the breeding season. To better understand the costs of reproduction, we investigated the relationship between female body condition (FBC) and the linear growth and body condition of their dependent calves (CBC). We documented a linear decline in the body condition of mature whales (0.027 m2/d; n = 20) and lactating females (0.032 m2/d; n = 31) throughout the breeding season, while there was no change in body condition of immature whales (n = 51) and calves (n = 32). The significant decline in mature and lactating female's body condition implies substantial energetic costs for these reproductive classes. In support of this, we found a positive linear relationship between FBC and CBC. This suggests that females in poorer body condition may not have sufficient energy stores to invest as much energy into their offspring as better conditioned females without jeopardizing their own body condition and survival probability. Measurement precision was investigated from repeated measurements of the same animals both from the same and different photographs, and by looking at residual errors in relation to the positioning of the whales in the photographs. The resulting errors were included in a sensitivity analysis to demonstrate that model parameters were robust to measurement errors. Our findings provide strong support for the use of UAVs as a noninvasive tool to measure the body condition of whales and other mammals.

Subfields: Atmospheric Science, Ecology, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/ba16a8ede3d5a823a71c5e66e5ff581db97704f0

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Citations in the corpus

Estimating body mass of free‐living whales using aerial photogrammetry and 3D volumetrics (2019, methodology): “In this study we present an approach to accurately predict the body mass of free-living large whales, using non-invasive unmanned aerial vehicle (UAV) photogrammetry (Christiansen, Dujon, Sprogis, Arnould, & Bejder, 2016; Christiansen et al., 2018) and historical catch records (Omura et al., 1969).”
Population comparison of right whale body condition reveals poor state of the North Atlantic right whale (2020, methodology): “…between body volume and body length, divided by the expected (or predicted) body volume for the individual (to standardized BCI across body size, Christiansen et al. 2013, 2016a, 2018): (3) where BVobs,i is the observed body volume of whale i in m3, and BVexp,i is the expected body volume of…”
Inexpensive Aerial Photogrammetry for Studies of Whales and Large Marine Animals (2017, background): “The simplest approach is to include in the image an object of known size, typically a boat (e.g., Whitehead and Payne, 1981; Christiansen et al., 2016), or projected laser dots a known distance apart (e.”
Noise Levels of Multi-Rotor Unmanned Aerial Vehicles with Implications for Potential Underwater Impacts on Marine Mammals (2016, methodology): “Altitudes of 5 and 10m may be used in the field for collection of exhalations (Acevedo-Whitehouse et al., 2010), but are in general well below more commonly used flight altitudes of >30m above marine mammals (Durban et al., 2015; Christiansen et al., 2016).”
Estimating morphometric attributes of baleen whales with photogrammetry from small UASs: A case study with blue and gray whales (2018, methodology): “2011, Christiansen et al. 2016), and include: body flex, nonhorizontal body position, light refraction on submerged body, deviations in camera roll, pitch (i.e., pointing angle) and yaw, as well as errors in reported range (e.g., distance from camera to whale). Jaquet (2006) used a wooden plank of k”