Absconding Colonies: Survival Outside the Hive

So Long and Thanks for All the Flowers

This is a followup investigation to my winter hive deaths. My three colonies are no more, having absconded from severe Varroa infestation. Absconding is when the colony quietly leaves the hive in search of a new home. It is not acontrolled process like swarming, where a new queen is formed and around half the colony leaves with the mother queen.

European Honey bees (Apis mellifera ligustica & A.m. carnica) are very tolerant of their nesting environments, how else could they live in roof cavities and the undersides of trampolines or vehicles? For a colony to abscond, their hive must severely degrade. This could be due to factors like prolonged forage shortages, environmental stress, disturbances (e.g. poor handling by beekeepers), and disease. As a result, the colony attempts to seek better survival conditions elsewhere, even if it happens to be in winter.

What drives absconding, and can bees prepare for it? Why are African bees more efficient absconders than their European counterparts, and why do other honey bee species perform migratory abscondments?

What Causes Bees to Abscond?

Bees abscond when their home environment deteriorates beyond tolerance. These degradations could be:

• Structural, as in large breaks in the hive material,
  • I’m sure there’s a beekeeper out there who once forgot to place the lid back on his hive. If left open long enough, the colony would abscond as they cannot manage the open area.
• Environmental, from extended periods without suitable forage,
  • “Extended” as in weeks or months. This is not like dearth, which is normal in the interval between flowering plants, or at the end of a summer.
• Pathological, as in prolonged disease infections and pest infestations.

Varroa intensifies all other conditions. What could have been a typical episode of Nosema disease becomes more intense when the feeding mites weaken adult bees. The colony becomes fragile, and an additional stressor (say, a brief cold snap) would result in absconding rather than an attempt to manage their current hive. This is the likely scenario for my hives. Where they absconded to, I do not know.

Varroa-Mediated Absconding

A discussion in my local beekeeping club was around winter hive losses from Varroa. Beekeepers reported colony losses that appeared as “absconding”, rather than complete collapse. A similar fate to my hives, who absconded from severe infestations. brood, honey and pollen were left behind in large quantities, as if the bees had no time to prepare and were forced out by the severe infestation.

In the literature, African bees (e.g. A. m. scutellata & A. m. capensis) abscond readily (“at a drop of a hat”), which is one adaptation for keeping disease burden Varroa populations low (Cheruiyot et al., 2020). Likewise, the Asian honey bee A. cerana swarms more often than A. mellifera and form smaller colonies, reducing the “per capita” burden of mites.

The beekeepers’ club suggested that this is a novel phenomenon. In Australia, colonies are not collapsing due to Varroa-borne disease like Deformed Wing Virus, rather due to the overwhelming pressure exerted by the feeding mites. Most of country has temperate weather, and there is no winter brood break. As such, Varroa continues to grow year-round, leading to losses.

Contrary to my alcohol wash results, it turns out that my 8-week flumethrin treatment was unsuccessful in managing or mites… Unless they got reinfested in large numbers after finishing treatments. You can never tell with bees.

The Process of Absconding

The literature identifies two forms of absconding: disturbance and seasonal (Spiewok et al., 2006). Seasonal absconding is another way of saying “migration” and is an adaption to the floral blooms in tropical regions – elaborated below. Disturbance-induced abscondment is what I experienced, and as the name suggests, the colonies abandon eggs, brood, and those remaining foragers in the field in response to… catastrophe. I am not exaggerating; European subspecies will remain inside their hive even when it’s heavily infested. They depart when they exceed their (rather-high) tolerance, as you’ll see below.

Cape honey bees (A.m. capensis) prepare for disturbance-induced absconding by reducing brood rearing (at times cannibalising young larvae to recycle nutrients), reducing foraging and increasing food consumption (Spiewok et al., 2006). This nest clean up ensures the bees are not wasting resources. As in swarming, upping the energy intake makes the colony better prepared to start anew, and just like swarming, they wait for optimal conditions (after rainy weather) to maximise the chance of survival.

The authors also observed one colony absconding and leaving their queen behind. Her Majesty’s pheromones are required for colony cohesion and swarm coordination (in addition to the scout bees). Could the queen have been unable to join her colony due to wing clipping or use of queen excluders? Unlikely, as I had not used these methods, nor was this the case in their study. Cape honey bees are unique in that workers can lay both male and female eggs, so a cloned female egg can be used to rear a new queen.

The bottom line is that Cape colonies could prepare for absconding, provided they have time and it’s not a highly destructive process (for example, lightening or bear attacks).

African Honey Bees are More Efficient at Absconding than European bees

African honey bees effectively prepare for absconding. These subspecies are highly mobile, an adaptation likely developed in response to the hostile ecosystem of Africa.

In severe small hive beetle infestations. A.m. scutellata & A.m. capensis quickly react to the presence of beetle larvae and will readily abscond rather than fend off a serious infestation (Spiewok et al. 2006). If you’ve looked inside one of those African hives, you’ll find less brood and honey per capita when compared to European bees.

The commonly-used Italian bee A.m. ligustica builds much larger colonies. Great for the native European climate, not so much for the African ecosystem. Neumann and colleagues found that European bees are more likely to remain in their nests even when overwhelmed by SHB or wax moth larvae (Neumann et al., 2018). They are less prepared for the process relative to African bees and are slower to abscond. Combined with a larger hive size, the departure of A.m. ligustica inevitably leaves more resources and brood behind.

This is what I observed in my absconding colonies – large amounts of brood and stores remaining for the scavengers to feed on. If European bees had developed adaptations that enabled them to prepare for the process before reaching the breaking point, then less resources would be left behind, and the colony could reallocate that energy into establishing their new nest.

Migration: Seasonal Absconding

Asian honey bees are known for their migratory lifestyles. Migration itself is a form of seasonal absconding, timed with the blooms of local plants. The giant honey bee A. dorsata migrates from the lowlands to highlands in east and south-east Asia following the forage. These bees will leave comb behind, but the contents are consumed preparation for the journey ahead. As in the above, African (but not Asian) honey bees would cannibalise young larvae to recycle nutrients.

The environmental triggers for seasonal absconding are multi-factorial, ranging from the start of monsoons to significant decreases in resources at the end of major flowering periods. The research of Robinson, 2012 and Robinson, 2021 showed that A. dorsata have communal bivouacking sites where the giant swarms will “rest” for a short number of days before continuing. Resting sites tend to be resource rich, and multiple A. dorsata swarms will rest alongside each other before continuing their journey, as shown below

Dwarf Honey Bees Abscond Faster in Response to Stressors

A more extreme example of absconding is found in A. florea. In response to predation, the bees abandon their current nest and rebuild at a new location. Unlike A. dorsata, Dwarf honey bee colonies are small, and can be supported by a thin branch. When preyed upon, a single avian predator can consume the entire colony’s bees without much effort. Rather than stay and defend, they pack up and leave; the adult lives are worth more than the brood and honey.

Should the colony abscond to a nearby location, the workers return to their old nest to salvage the wax (Pirk et al., 2011). When do bees return for salvage, and when do they start anew? The authors identified two tradeoffs: whether recovering or replacing old wax is more favourable. They found that when the new nesting site is less than 200 meters away, it is energetically favourable to salvage and recycle the wax comb. Otherwise, they’re better off foraging and using that energy to produce new wax scales.

What if the Bees Choose Poorly?

If the bees abscond to a location that is good in the short term and detrimental long term (say, a stormwater pipe), then the colony dies. Or be forced to abscond again. The latter is unlikely, as unlike swarming, the worker bees are not loaded with honey, and they lack the resources to redeploy themselves. Any future stressor would overwhelm this struggling colony, highlighting the dangers of sudden absconding.

Remember, African honey bees are less impacted than their European counterparts, for they have adaptions to rapidly abscond and locate a new nesting site.

Is Absconding a Sign of Weakness?

Depending on your perspective, absconding can be seen as a sign of weakness. One viewpoint could be that “these bees were no longer able to stand the stressors and had to leave. They are weak”. Sure, there’s merit to this, but everything has limits. For example, if colony A absconded after a mite count of 10,000 and colony B from a mite count of 1,000, they’d both be classified “weak”, yet we’d know colony A was far stronger.

The strength of the colony is determined in the weeks prior to the absconding. Were they bringing in plenty of forage? Was the worker population large relative to other hives in the apiary?¹. In my case, the daytime temperatures were averaging 12°C, warm enough for a colony to take flight, and the few dead bees that were spotted are the returning foragers, coming home to an empty nest. If a colony were truly weak, it would not have the strength to abscond, and thus die inside the hive – a common sighting in pesticide poisoning.

Preventing Abscondment

Bees abscond due to an unfavourable nesting environment. Your job as the beekeeper is to maintain these optimal conditions by:

• Ensuring hives have sufficient food resources. During the summer dearth, use an internal feeder to provide them with sugar syrup and/or pollen patties, this reduces the chances they’ll engage in robbing, and reduces the absconding tendencies. After all, there’s food at home, so why risk going elsewhere?
• Reducing environmental stress. In warm climates, thermal stress is an issue – use ventilated hive bases and place hives in a location sheltered from the afternoon sun. Can’t find a sheltered place? Cover bees with a tarp to reduce the sun’s impact. Remember to remove it when the weather gets cold!
  • The hive position should shelter then from extreme conditions. I consider the gold standard to be north-facing and in the cover of a deciduous tree (those that shed their leaves in the winter). This ensures hives get the morning sun in winter, and shade in the summer afternoons.
  • For stingless bee beekeepers, temperature stress is a strong contributor to absconding in tropical regions (Freitas et al., 2008).
  • Use the right type of hive material. For example, a polyurethane hive may be better for warm, dry environments than wood on account of its superior insulative properties.

• Controlling pests and disease. Varroa was the primary cause of absconding in my case. My summer treatments did not work, and my choice to not retreat right away led to their demise.
  • Other pests like small hive beetles or wax moths increase the likelihood of absconding.
    • Ellis and colleagues found that the European subspecies were more likely to abscond from an initial SHB infestations than their African counterparts (A.m. capensis), due to a lack of adaptations against this invasive beetle. (Ellis et al., 2003). Indeed, the Cape bees jail these beetles in prisons of propolis, whilst the European bees would only harry them into a corner. Eventually the infestations become severe and the European colony can no longer sustain it, leading to abscondment.
• Minimising disturbances. Limit your hive inspections and inspect properly. Don’t open the hives for the fun of it– do it when there’s a need and the weather is right. “Frequent” hive management could be every 10-14 days for the purposes of swarm control.

What I’m Doing Differently After Absconding

I write these lines in early spring. I’ve sourced a five-frame nuc of bees to restart my apiary, and will attempt to treat bees every winter. Summer and spring treatments will be based on severe infestations. In an ideal world, the hives would be placed in a north-facing facing position with shelter from the afternoon sun. Alas, I do not have this luxury.

It’s really about Varroa management. The gentlemen at the beekeeper’s club suggest that Varroa-mediated late winter absconding is a new phenomenon – whether to Australia or the world, that is to be determined.

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Footnotes

1. If you’ve only got one hive, then an outside inspection is not always sufficient. Open up and check their food stores, brood populations and signs of other pests like small hive beetles – if the former two are present in large numbers and the latter pests are few, then you can be confident it’s the stronger hive. ↩︎