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This is the first study to characterize sleep behavior in wild black rhinos. This study resulted in a greater understanding of the biologic factors that affect sleep in wild rhinos and can provide information to assist their management and conservation.

Summary1. Hormone analyses are frequently used to support management of wildlife; however, current techniques are not very field-friendly. In situ hormone monitoring is often expensive, time consuming and logistically difficult. Thus, a new method for assessing ovarian cycle activity non-invasively in free-ranging African elephants was developed. 2. The technique involves handshaking faecal samples in common organic solvents, use of environmentally stable antibody-coated microtitre plates and assessment of progestagen concentrations based on a visual colour change. 3. Studies using ex situ African elephants determined that handshaking faeces in a solution of isopropyl alcohol was effective for extracting the faecal progestagens (efficiency >90%). 4. Antibody-coated plates were stable for up to 3 months under a range of temperatures (4 to >38°C) and the resulting faecal oestrous cycle progestagen profiles corresponded significantly to those of serum (r = 0AE89, P < 0AE01). 5. This field-friendly technique provided qualitative hormone data without the need for expensive equipment. Although developed for progestagen analyses in elephants, this approach should be adaptable to other steroids in a myriad of species. As such, it could facilitate how hormones are measured in species under field conditions and provide new tools for making sensible conservation management decisions.

Absence of apex predators simplifies food chains, leading to trophic degradation of ecosystems and diminution of the services they provide1. However, most predators do not coexist well with humans, which has resulted in a decline of carnivores and functional ecosystems worldwide2. In some instances, cryptic carnivores manage to survive amidst human settlements, finding refuge in small biological islands surrounded by urban landscapes. In such a system, we used two non-invasive data collection methods (camera trapping and fecal sampling) to investigate the multiannual relationship between predators and prey, and between competitors, through analysis of: (1) relative abundance and detection probability of species over time, (2) causal interactions via empirical dynamic modeling, (3) diet, and (4) diel activity patterns. All approaches show concordance in the results: the natural return of an apex predator, the puma (Puma concolor), triggered a trophic cascade, affecting the abundance and behavior of its main prey, subordinate predators and other prey in the studied system. Our study demonstrates that trophic recovery can occur rapidly following the return of a top predator, even in small protected areas in increasingly urbanized landscapes.

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