If your property suddenly shows more mounds, soft spots, or chewed lines in late winter and spring, you’re not imagining it. For most burrowing species, spring is the primary breeding surge, driven by warmer soils, higher food availability, and ideal nesting conditions. Understanding when and how they reproduce helps you create a treatment schedule for the biggest impact.
Who breeds when (typical patterns)
(Exact timing varies by region and weather; use these as practical ranges.)
- Pocket gophers: Peak breeding occurs in late winter–spring; some areas see a smaller fall pulse. Often 1–3 litters/year, ~3–6 young.
- Ground squirrels (e.g., California/Columbian): One litter/year in spring, typically 5–8 pups. Adults may overwinter; juveniles emerge late spring/early summer.
- Moles: Once/year—late winter to early spring; 2–5 young. Tunnel expansion and mound building often spike around breeding and shortly after.
- Voles: Highly prolific. Multiple litters/year spring through fall; populations can swell rapidly along edges and in cover.
- Rats (Norway/roof): In mild climates, year-round; litters every 3–5 weeks. Burrow activity near structures and embankments often intensifies with nearby food/water.
- Prairie dogs: One litter/year in spring; pup emergence follows several weeks later.
Why timing matters
Breeding season isn’t just about babies—it’s about network growth. Nest chambers, refuge burrows, and new forage runs connect into larger systems. If you interrupt those systems before juveniles disperse, you:
- Reduce the first big population spike.
- Prevent new galleries from linking to irrigation, fence lines, or high-value turf.
- Cut repeat visits later in the season.
How to turn biology into results
1) Sweep before the spike.
Plan a pre-breeding sweep (late winter/early spring) targeting perimeters and hot spots: fence lines, valve boxes, drip lines, berms, bunker/rough transitions, animal enclosures, retaining slopes.
2) Confirm active runs.
Use a probe to locate tunnels; poke-test and check in 24–48 hours for re-plugging. Treat active lines first for faster gains.
3) Treat the network—not just the hole.
With BurrowRx Carbon Monoxide Sprayer, insert the exhaust nozzle and start the engine; use smoke oil to see where gas is traveling. As tinted plumes reveal hidden exits, seal vents in real time so the system holds gas throughout the galleries.
4) Adjust by soil and run length.
- Sandy soils collapse more readily—expect longer run times and more vent sealing.
- Clay/loam holds shape—smoke tracing is clearer; keep sealing until plumes stop. A practical rule of thumb: ~3 minutes per 15–20 ft of continuous run, then reassess.
5) Sweep again during juvenile emergence.
Four to six weeks after peak breeding, do a follow-up sweep to suppress dispersing juveniles before they establish new networks.
6) Coordinate across boundaries.
Burrow systems cross fences. Where neighbors can’t be treated, consider boundary trapping as a supplement to reduce re-infestation pressure.
Quick field checklist
Breeding season isn’t just about babies—it’s about network growth. Nest chambers, refuge burrows, and new forage runs connect into larger systems. If you interrupt those systems before juveniles disperse, you:
- Map perimeters and high-risk zones
- Probe → poke-test → mark active lines
- Treat with smoke-oil visualization; seal as you go
- Log run times and soil notes for each zone
- Recheck in 7–10 days; repeat on stragglers
- Schedule a juvenile-emergence sweep
Why this approach changes the math
A biology-timed, network-based method replaces guesswork with visible coverage and fewer retreats or callbacks. Crews spend less time chasing single holes and more time closing entire systems—reducing labor drag, surface damage, and infrastructure hits. And because treatment occurs inside sealed tunnels, exposure to non-target species is minimized when used as directed.
Next step: Want a site-specific spring plan (with zone maps and run-time presets)? Connect with your regional BurrowRx rep and we’ll help you set it up.
About BurrowRx
Designated as a pest control device by the Environmental Protection Agency (EPA), BurrowRx Carbon Monoxide Sprayer is designed to control burrowing and tunneling animals, including gophers, ground squirrels, moles, rats, and prairie dogs. BurrowRx Carbon Monoxide Sprayer uses a smoke oil tracer to show where the carbon monoxide is going in the tunnels. As the carbon monoxide enters the burrow system, the rodent breathes it replacing oxygen in its blood and causing the organs to stop working. The product is unlikely to harm any non-target species because once it completely dissipates, the carbon monoxide is no longer a risk to anything entering the burrow system.
For more information about the solution for burrowing pests, visit BurrowRx at www.BurrrowRx.com or call (619) 442-8686. Also, visit the BurrowRx channel on YouTube.