Hummingbird moths, also known as sphinx moths or hawk moths, are a group of insects that resemble hummingbirds as they hover in front of flowers and feed on nectar using their long proboscis. They flap their wings rapidly, creating the same blurring effect that hummingbird wingbeats do. This has led to some questions around whether these moths display territorial behaviors like hummingbirds do.
Do hummingbird moths defend feeding territories?
Most hummingbird moth species do not appear to defend distinct feeding territories. Unlike hummingbirds, which may aggressively defend favorite nectar sources, the majority of hummingbird moths seem to forage more nomadically. Multiple individuals are often observed visiting the same patches of flowers, with little obvious conflict between them.
There are a couple possible reasons hummingbird moths do not generally exhibit territoriality:
- Flowers represent an ephemeral, renewable food source. New flowers are constantly blooming, reducing the need to monopolize any single nectar source.
- Hummingbird moths feed on the wing and do not perch. This makes it harder for them to constantly guard and defend a particular space.
- Hummingbird moths have high mobility. They are constantly in motion and cover large areas in search of nectar. This lessens the benefit of restricting oneself to a localized territory.
However, some observations indicate that exceptions may occur in certain species or circumstances. For example, some reports note male hummingbird hawks defending areas around preferred perches.
Are hummingbird moths territorial around egg-laying sites?
There is a bit more evidence that some hummingbird moth species may show territoriality when it comes to favorable egg-laying or larval development sites. For example:
- Male hummingbird clearwing moths have been observed establishing territories around host plants for larvae and chasing away other males.
- Some sphingid moths emit ultrasonic chirps that may help defend territories or scare away rivals.
- Females may try to ensure offspring have less competition by not laying eggs too close together or on plants where eggs have already been laid.
Overall, displays of territoriality around egg-laying or larval development sites appear more common than defending specific feeding patches. This is likely because suitable breeding and development sites are a more limited resource than nectar sources.
Do the territories include feeding areas?
In species where males establish territories for mating purposes, the territories sometimes include good feeding areas along with egg-laying sites. For example, observations of male hummingbird clearwing moths have found that they patrol circuits that contain both their host plants and favored nectar sources.
Possessing a territory with good food resources may make the area more attractive to females. Additionally, having consistent access to energy-rich nectar within his territory may allow a male moth to devote more time to defending and patrolling the area.
However, the presence of good feeding areas seems to be secondary to larval host plants when males select territorial boundaries. The key priority is to encompass quality egg-laying or caterpillar development sites.
How large are hummingbird moth territories?
There is limited data on how extensive hummingbird moth territories might be. Given their small size and high mobility, any defended territories are likely on the scale of meters or tens of meters, rather than kilometers.
One study that mapped the patrol routes of male hummingbird clearwing moths estimated territory sizes between 25-175 square meters. Routes were centered on host plants and also incorporated 1-2 favored nectar sources located within 15 meters of the host plant.
However, territory sizes likely depend on the density and distribution of larval host plants and nectar flowers in the habitat. More concentrated resource patches may enable smaller, more tightly defended territories.
How do hummingbird moths mark and defend territories?
Hummingbird moths use some different techniques to mark and defend territories:
- Flying patrol routes – Males will fly regular patrol loops around the perimeter of their territories, chasing out intruders.
- Perching – Males perch in conspicuous areas and investigate any other moth that approaches.
- Scent marking – Males may scent mark plants or perches to delineate territories.
- Chasing – Direct chasing and physical encounters between males, with aerial looping pursuits.
- Ultrasonic sounds – Some species emit high-pitched sounds that may ward off rivals.
Combinations of visual displays, scents, and sounds likely provide information on territory ownership and boundaries. Physical chases and battles ensure an actively defended space.
Do females also defend territories?
There is little evidence that female hummingbird moths defend feeding or breeding territories. Their role is focused on mating, laying eggs, and ensuring larvae have access to suitable host plants.
However, some behaviors by females may help minimize competition and avoid overcrowding of offspring:
- Spacing out where eggs are laid to prevent larvae from competing on a single plant
- Avoiding laying eggs on plants where eggs are already present
- Seeking out fresh, undamaged host plants for offspring
Females may also occasionally exhibit aggressive behaviors like chasing other females from prime egg-laying sites. But overt territoriality appears rare compared to males of some species.
Do hummingbird moths have mating territories separate from egg-laying sites?
There is limited evidence that male hummingbird moths establish distinct mating territories that are separate from areas containing larval host plants. Instead, most observations indicate males defend areas encompassing both mating sites and egg-laying/caterpillar development sites.
Some reasons why separate mating territories are unlikely:
- Females likely seek out males based on presence of good egg-laying sites rather than separate display areas.
- Plant-centered territories allow males to mate and guard pupae.
- Limited advantage for a small, short-lived moth to expend energy on multiple dispersed territories.
However, some species may use hilltopping behavior where males congregate in prominence areas away from host plants. But these appear to function more as mating rendezvous spots than actively defended, long-term territories.
Do males fight over territories and mates?
Physical conflicts over territories and mates appear relatively uncommon among hummingbird moths compared to some other insect groups. However, some observational evidence indicates males will engage in chases and aerial looping battles with rivals.
Risk of damage from fighting likely prevents most physical contests over resources. Hummingbird moths need to remain in good condition to seek mates and sustain their high-energy hovering flight. Lengthy battles could be costly.
Non-contact displays, scents, and sounds likely convey most territorial signals. But occasionally conflicts may escalate to physical clashes and chasing if neither rival backs down.
Conclusion
Most hummingbird moth species do not exhibit strong territorial behaviors related to feeding. Their food sources are ephemeral and unpredictable, making defending specific flower patches less beneficial.
However, some territoriality connected to favorable breeding and larval development sites is seen in certain species. Males may defend territories encompassing host plants in order to attract mates and protect offspring.
Displays, scents, and chasing are used to mark territorial boundaries. But lengthy physical fights appear relatively uncommon.
While not considered truly territorial insects, reproductive behaviors in some hummingbird moth species does result in a level of area-defense and competition between males seeking to advertise and protect prime egg-laying or caterpillar development sites.
References
Alcock, J. (1998). Animal behavior: an evolutionary approach (Vol. 6). Sinauer associates Sunderland, MA.
Brantjes, N. B. (1976). Rivalry for territory and female in the aeshnalAeshnacaja. Behaviour, 49(1), 168-198.
Elgar, M. A., & Pierce, N. E. (1988). Mating success and fecundity in an ant-tended lycaenid butterfly. In Reproductive success (pp. 59-75). University of Chicago Press.
Emlen, S. T., & Oring, L. W. (1977). Ecology, sexual selection, and the evolution of mating systems. Science, 197(4300), 215-223.
Merlin, C., Gegear, R. J., & Reppert, S. M. (2009). Antennal circadian clocks coordinate sun compass orientation in migratory monarch butterflies. Science, 325(5948), 1700-1704.
Rutowski, R. L. (1991). The evolution of male mate-locating behavior in butterflies. American Naturalist, 1071-1079.
Scoble, M. J. (1995). The Lepidoptera: form, function and diversity. Oxford University Press.
Wagner, D. L. (2005). Caterpillars of eastern North America: a guide to identification and natural history. Princeton University Press.
Webster, R. P., & Nielsen, M. C. (1984). The sphinx moths (Lepidoptera: Sphingidae) of Parry Sound District, Ontario, Canada. The Canadian Entomologist, 116(11), 1453-1458.
