Fleet Size Calculator

How many tunnels and units do you need?

Enter your site parameters. The calculator accounts for population growth during the knockdown period, operational hours, days per week, and diurnal activity — giving you accurate fleet allocations for both the knockdown phase and long-term maintenance.

Live · DB-driven species

Exponential growth · Population model

Tunnels + Units + PDF · Output

APC-N1, APC-N4 & APC-N8 · Models

Tunnel capacity reference — live (per tunnel, based on your operational settings below)

4.0

Effective rate

birds/hr per tunnel

Per day

8h/day

160

Per week

5 days/wk

695

Per month

30.42 days avg

Deployment parameters

Target speciesSpecies are loaded live from the pest species database. Tunnel size and recommended model are derived from the species' standing height — the tunnel opening must admit the bird comfortably while excluding larger non-target species. T1/T2 → APC-N8 or APC-N1; T3/T4 → APC-N4 or APC-N1.

Loading species…

Monthly growth rate (g)Natural monthly population growth rate — births minus natural deaths. Typical values: 0.08 (geese) to 0.20 (sparrows). This is the rate the population grows WITHOUT any extraction.

12%

Unit modelAPC-N8 carries T1/T2 tunnels for birds up to 400 mm standing height (starlings, mynas, sparrows, pigeons). APC-N4 carries T3/T4 tunnels for birds over 400 mm (crows, geese, ibis). APC-N1 is a single-tunnel unit available in all four tunnel sizes.

Current population (N₀)Your best estimate of the current resident pest bird population. Use roost counts, survey data, or a conservative field estimate.

Target population (Nₜ)The residual population you want to reach at the end of the knockdown phase. Zero = full eradication. A small residual is typical for ongoing management programs.

Knockdown timeframe (months)How many months to achieve the target population. Longer timeframes require fewer tunnels. Shorter timeframes require more — but also fight harder against population growth.

3 months

Operational hours per dayHow many hours per day the unit operates. Default 12h matches the diurnal activity window for most pest species. Increase for nocturnal or mixed-activity species.

8h/day

Operational days per weekHow many days per week the unit operates. 7 days is standard for continuous deployment. Reduce for sites with restricted access or scheduled maintenance windows.

5 days/wk

Effective process rate per hourHow many birds per hour the tunnel realistically processes. The theoretical maximum is 12 birds/hr (1 bird per 5 min, continuous) — but birds don't queue without gaps. A conservative field estimate is 2–5 birds/hr depending on site pressure, species behaviour, and bait effectiveness. This is the single biggest lever on fleet size.

4.0 birds/hr

Equivalent active time20 min/hr

Tunnel utilisation33%

Fleet allocation

Population trajectory

Managed vs unmanaged · offspring stacked on population

View12 months

Managed population

Natural offspring (stacked)

Unmanaged population

Monthly extraction

Loading chart…

Blue area = managed population · amber area = natural offspring stacked on top · dashed red = unmanaged trajectory · blue bars = monthly extraction. Vertical dashed line marks end of knockdown (month 3).

APC-N8— T1/T2 tunnels — birds up to 400 mm standing height

Population growth accounted for. Without intervention, this population would grow from 30,000 to approximately 42,148 birds over 3 months at 12%/month. The fleet allocation below is sized to overcome this growth and still reach 100 birds.

Important limitations: This model assumes constant exponential growth and does not account for seasonal breeding cycles, natural predation, food supply constraints, or the carrying capacity of the local environment. Results represent a worst-case approximation intended to guide fleet sizing — actual population dynamics will vary.

Phase 1 — Knockdown

3 months: 30,000 → 100 birds

Tunnels required

99.6% utilisation

APC-N8 units

8 tunnels/unit

12,460.8

Monthly extraction

birds/month (constant)

E = (N₀×(1+g)ᵀ − Nₜ) × g / ((1+g)ᵀ − 1) = (30,000×(1+12%)^3 − 100) × 12% / ((1+12%)^3 − 1) = 12,460.8 birds/month

Tunnels = ⌈12,460.8 ÷ 695.3 capacity/tunnel⌉ = 18 tunnels → ⌈18 ÷ 8 tunnels/unit⌉ = 3 units

After knockdown — fleet utilisation

Same 3 × APC-N8 fleet

Holding at target (100 birds)0.1% utilisation

12.0 birds/month extraction needed · fleet has significant spare capacity

If unmanaged — holding at 42,148 birds40.4% utilisation

5,057.7 birds/month would be needed to hold an unmanaged population flat

Knockdown unlocks spare capacity. Once the population reaches 100 birds, the same fleet drops to just 0.1% utilisation — removing only 12.0 birds/month to hold the population flat. This compares to 40.4% utilisation that would be needed to hold an unmanaged population of 42,148 birds.

Summary

Fleet allocation3 × APC-N8 (18 tunnels)

Knockdown utilisation (3 months)99.6%

Post-knockdown utilisation (holding at 100)0.1%

Utilisation needed if unmanaged (42,148 birds)40.4%

Effective processing rate4.0 birds/hr per tunnel

Tunnel capacity (per tunnel/month)695 birds

Operational window8h/day × 5 days/wk

Monthly growth rate12%/month

Unmanaged population at 3 months42,148 birds

Methodology: Population growth is modelled as N(t) = N(t−1)×(1+g) − E each month, where g is the monthly natural growth rate and E is the constant monthly extraction. The extraction formula E = (N₀×(1+g)ᵀ − Nₜ)×g / ((1+g)ᵀ − 1) is the financial PMT function adapted for population dynamics. Post-knockdown holding extraction = Nₜ×g. Effective tunnel rate = 4.0 birds/hr. Tunnel capacity = 4.0 birds/hr × 8h/day × 5 days/wk ÷ 7 × 30.42 days/month = 695 birds/month/tunnel. All units rounded up to nearest whole number.

Export this report

Download a plain-text copy of this fleet allocation report, or send it directly to the Avian Pest Control team to request further information or a site-specific quotation.

Technical reference

Tunnel capacity conversion table

Processing time is 5 minutes per bird per tunnel. The effective process rate is set directly — it represents how many birds per hour the tunnel realistically handles given idle time between captures. The table below shows theoretical maximum (12 birds/hr), a typical field estimate (4 birds/hr), and your current setting (4.0 birds/hr).

Interval	Max (12 birds/hr)	Typical (4 birds/hr)	Your setting (4.0 birds/hr)
Per hour	12 birds	4.0 birds	4.0 birds
Per day (8h)	96 birds	32 birds	32 birds
Per week (5d)	480 birds	160 birds	160 birds
Per month	2,086 birds	695 birds	695 birds

Effective process rate is the single most significant variable in fleet sizing. Doubling the rate from 4 to 8 birds/hr halves the number of tunnels required. Use conservative estimates — overestimating throughput leads to under-allocation and missed knockdown targets.

Unit reference

APC model comparison

Model selection is based on tunnel size, which is determined by the target species' standing height. T1/T2 tunnels fit birds up to 400 mm; T3/T4 tunnels fit larger species.

APC-N8

Small to medium birds

8 tunnels/unit

T1 / T2 tunnels

up to 400 mm standing height

House Sparrow

~120 mm

Common Starling

~200 mm

Indian Myna

~230 mm

Feral Pigeon

~320 mm

11,681

birds/month per unit (12h/day, 7d/wk, 4 birds/hr)

APC-N4

Large birds

4 tunnels/unit

T3 / T4 tunnels

over 400 mm standing height

Crow / Rook

~450 mm

Cockatoo

~480 mm

Gull (Larus spp.)

~550 mm

Ibis

~700 mm

Canada Goose

~900 mm

5,841

birds/month per unit (12h/day, 7d/wk, 4 birds/hr)

How tunnel size is assigned: Each species is assigned a tunnel size based on its average standing height — the tunnel opening must admit the bird comfortably while excluding larger non-target species. T1 (≤260 mm) and T2 (261–400 mm) tunnels are carried by the APC-N8 and APC-N1; T3 (401–500 mm) and T4 (>500 mm) tunnels are carried by the APC-N4 and APC-N1. Species data is loaded live from the pest species database — as new species are added or heights are updated, the calculator reflects those changes automatically. Growth rates are derived from each species' life-history data (offspring per year and lifespan).

Ready to scope your deployment?

Our team can validate your fleet estimate against site-specific factors — roost density, site geometry, seasonal population variation, and regulatory requirements.

Discuss your deployment View the APC-N8 & APC-N4