The Hoopoe (Upupa epops) is a medium-sized bird, unmistakable for its colorful plumage and prominent fan-shaped crest. Its body is primarily reddish-brown, with striking black and white bands on the wings and tail. The crest, which can be raised or lowered, is brown with black tips. The hoopoe's long, slender, and curved beak is perfectly suited for probing the ground in search of insects and larvae, its main food source. The bird is also known for its distinctive call, which sounds like "oop-oop-oop."

Scientific Classification:

• Kingdom: Animalia
• Phylum: Chordata
• Class: Aves
• Order: Bucerotiformes
• Family: Upupidae
• Genus: Upupa
• Species: Upupa epops

Dimensions and Weight: The hoopoe measures between 25 and 29 cm in length, with a wingspan of 44 to 48 cm. Its average weight ranges from 46 to 89 grams, with males typically being slightly larger than females.

Habitat: The hoopoe inhabits a wide range of environments, from agricultural plains to open woodlands, grasslands, and arid regions. It prefers areas with sparse vegetation, where it can easily forage for insects on the ground. The bird often nests in tree cavities, walls, or rock crevices. Its geographic distribution spans much of Europe, Asia, and Africa, with migrations southward during winter.

Behavior and Habits: The hoopoe is a solitary bird or one that forms pairs during the breeding season. It is known for its distinctive feeding behavior: it uses its long beak to dig into the ground to find insects, larvae, worms, and small invertebrates. When threatened, the hoopoe raises its crest as a defensive display. Breeding season varies by region, but typically occurs between April and July. The female lays 5 to 7 eggs in a hidden nest, often in a cavity.

Dangers, Enemies, and Threats: The hoopoe's predators include birds of prey, snakes, and predatory mammals that may raid its nests for eggs or chicks. However, the primary threat to the hoopoe is habitat loss due to intensive farming and urbanization. The widespread use of pesticides reduces the availability of insects, depriving the hoopoe of its primary food source. Additionally, the destruction of natural nesting cavities poses a significant threat.

Protected or Endangered Species: The hoopoe is not globally endangered, but it is protected in many European countries due to declining local populations. The hoopoe is listed in Appendix II of the Bern Convention and the EU Birds Directive, which protect its habitat and regulate hunting. Populations are regularly monitored to ensure the species' conservation.

References__________________________________________________________________________

Díaz-Lora S, Pérez-Contreras T, Azcárate-García M, Peralta-Sánchez JM, Martínez-Bueno M, José Soler J, Martín-Vivaldi M. Cosmetic coloration of cross-fostered eggs affects paternal investment in the hoopoe (Upupa epops). Proc Biol Sci. 2021 May 12;288(1950):20203174. doi: 10.1098/rspb.2020.3174. 

Abstract. The signalling hypothesis suggests that avian eggshell coloration is a sexually selected female signal advertising her quality to its male partner, thereby stimulating his provisioning rate. This hypothesis has been tested for structural eggshell pigments, but not for cosmetic colorations, such as that produced by the uropygial secretion on eggshells. During the breeding season, female hoopoes (Upupa epops) host in their uropygial glands symbiotic bacteria. Females actively smear the eggshells with their secretion, protecting embryos from pathogenic trans-shell infections and changing eggshell coloration. Because the colour of the secretions is related to their antimicrobial potential, cosmetic eggshell coloration may act as a cue or even as a post-mating sexually selected signal if it affects male provisioning rates. To experimentally test this hypothesis, we cross-fostered already-smeared clutches between hoopoe nests, and quantified male feeding behaviour to females before and after the experiment. This approach allows disentanglement of the effects of female quality and of egg coloration on male investment. In accordance with the hypothesis, males adjusted their provisioning rate to the eggshell cosmetic coloration. This is, to our knowledge, the first experimental demonstration that egg colour stained with uropygial secretion could act as a post-mating sexual signal of female quality to males.

Soler JJ, Martín-Vivaldi M, Nuhlíčková S, Ruiz-Castellano C, Mazorra-Alonso M, Martínez-Renau E, Eckenfellner M, Svetlík J, Hoi H. Avian sibling cannibalism: Hoopoe mothers regularly use their last hatched nestlings to feed older siblings. Zool Res. 2022 Mar 18;43(2):265-274. doi: 10.24272/j.issn.2095-8137.2021.434. 

Abstract. Sibling cannibalism is relatively common in nature, but its evolution in birds and certain other vertebrates with extended parental care had been discarded. Here, however, we demonstrate its regular occurrence in two European populations of the Eurasian hoopoe (Upupa epops) and explore possible adaptive and non-adaptive explanations. Results showed that sibling cannibalism was more frequently detected in Spain (51.7%) than in Austria (5.9%). In these two populations, the hoopoes laid similar clutch sizes, resulting in similar fledging production, but hatching failures were more frequent in the northern population. Consequently, having more nestlings condemned to die in the southern population may explain the higher incidence of sibling cannibalism. In accordance with this interpretation, hatching span and failure, but not breeding date, explained the probability of sibling cannibalism in the Spanish hoopoes, while all three variables predicted brood reduction intensity. Furthermore, experimental food supply reduced the probability of sibling cannibalism, but not the intensity of brood reduction. Finally, females allocated fewer resources to the smallest nestlings when they were going to starve, but not necessarily when they were going to be used as food for their siblings. These results suggest that hoopoes produce extra eggs that, in the case of reduced hatching failure and food scarcity, produce nestlings that are used to feed older siblings. These findings provide the first evidence that sibling cannibalism occurs regularly in a bird species, thus expanding our evolutionary understanding of clutch size, hatching asynchrony, parent-offspring conflict, infanticide, and sibling cannibalism in the animal kingdom.

Plard F, Arlettaz R, Schaub M. Hoopoe males experience intra-seasonal while females experience inter-seasonal reproductive costs. Oecologia. 2018 Mar;186(3):665-675. doi: 10.1007/s00442-017-4028-8.

Abstract. Reproductive and survival costs due to reproductive investment are a central element for the evolution of life histories. Both intra- (reduction of reproductive performance of second brood due to investment in first brood) and inter-seasonal costs (reduction of reproductive performance or annual survival due to reproductive investment in preceding year) may appear in multiple breeding species. Knowledge about how trade-offs within and between seasons shape individual trajectories and influence fitness are crucial in life-history evolution, yet intra- and inter-seasonal reproductive costs are rarely analysed simultaneously. We investigated sex-specific differences in intra- and inter-seasonal reproductive and survival costs in response to previous reproductive effort in a monogamous, double-brooding bird, the hoopoe (Upupa epops), accounting for heterogeneity in individual and annual quality. Intra-seasonal reproductive costs were detected in males and inter-seasonal reproductive and survival costs were detected in females. In males, the probability of being a successful double breeder was negatively correlated with the number of hatchlings produced in the first brood. In females, the number of fledglings raised in the first brood was negatively correlated with the reproductive effort in the preceding season. Female annual survival was also negatively influenced by the number of broods produced in the previous reproductive season. Most of these reproductive costs were detected only in years with low productivity, suggesting that costs become evident when environmental conditions are harsh. Our results illustrate how different investment in current vs. future reproduction and survival shape different life-history strategies in males and females of a monogamous bird species.

Soler JJ, Martín-Vivaldi M, Peralta-Sánchez JM, Arco L, Juárez-García-Pelayo N. Hoopoes color their eggs with antimicrobial uropygial secretions. Naturwissenschaften. 2014 Sep;101(9):697-705. doi: 10.1007/s00114-014-1201-3. 

Abstract. Uropygial gland secretions are used as cosmetics by some species of birds to color and enhance properties of feathers and teguments, which may signal individual quality. Uropygial secretions also reach eggshells during incubation and, therefore, may influence the coloration of birds' eggs, a trait that has attracted the attention of evolutionary biologists for more than one century. The color of hoopoe eggs typically changes along incubation, from bluish-gray to greenish-brown. Here, we test experimentally the hypothesis that dark uropygial secretion of females is responsible for such drastic color change. Moreover, since uropygial secretion of hoopoes has antimicrobial properties, we also explore the association between color and antimicrobial activity of the uropygial secretion of females. We found that eggs stayed bluish-gray in nests where female access to the uropygial secretion was experimentally blocked. Furthermore, experimental eggs that were maintained in incubators and manually smeared with uropygial secretion experienced similar color changes that naturally incubated eggs did, while control eggs that were not in contact with the secretions did not experience such color changes. All these results strongly support the hypothesis that female hoopoes use their uropygial gland secretion to color the eggs. Moreover, saturation of the uropygial secretion was associated with antimicrobial activity against Bacillus licheniformis. Given the known antimicrobial potential of uropygial secretions of birds, this finding opens the possibility that in scenarios of sexual selection, hoopoes in particular and birds in general signal antimicrobial properties of their uropygial secretion by mean of changes in egg coloration along incubation.