Family Planning Services : An Essential Component of Preconception Care Family planning services are necessary for the widespread adoption of preconception care for two reasons . First , preconception care is more likely if pregnancies are planned , and family planning services encourage pregnancy planning . Second , family planning services usually include counseling , and counseling provides an opportunity to discuss the advantages of preconception care . However , the potential of family planning services to promote preconception care is limited by underutilization of these services and inadequate attention to preconception care during family planning visits . This article suggests ways to reduce these problems . If all women of reproductive age , or at least those at elevated risk , are to benefit from preconception services , the use of family planning services must be increased and the content of such services expanded . Family planning services are essential for preconception care for at least two reasons . First , in the absence of such services , pregnancies will occur that have not benefited from preconception care . Preconception care during the reproductive years is dependent on women and men planning their pregnancies , not only in respect to their timing but also to health-related factors that would maximize the chances for a healthy pregnancy and a healthy infant . In the absence of such care , offered by family planning services , many pregnancies will not benefit from preconception advice . Second , family planning counseling provides an opportunity for promoting and providing preconception care . At the same time women and their partners are receiving advice about family planning , they can also receive instruction about the range of activities that lead to healthy pregnancies and healthy infants . Unfortunately , several factors prevent family planning from reaching its maximal potential for preconception care . These include underutilization of family planning services and inadequate attention to preconception counseling during family planning visits . Underutilization of family planning services Two types of data point to underutilization of family planning services with implications for decreasing opportunities for preconception care : the percentage of women actually seeking family planning services and the percentage of unintended pregnancies . Visits for family planning The 2002 National Survey of Family Growth -LRB- NSFG -RRB- reported that 41.7 % of women 15 to 44 years of age received at least one family planning service from a medical care provider in the 12 months prior to the interview -LSB- 1 -RSB- . This percentage is not as alarming as it might appear at first glance , because some of the women who did not seek family planning services already were pregnant , seeking to become pregnant , or infertile because of sterilization or other reasons . Nevertheless , this rather low percentage suggests that some women are not planning their pregnancies either deliberately or because they are experiencing problems obtaining family planning services . Pregnancy planning It is undoubtedly true that some women do not wish to plan the timing of their pregnancies . In many cases , these are married women who have religious objections to family planning . In Women of Crisis , one woman states `` you do n't think of life that way -- of having children that way . You do n't sit down and say you can afford to have a certain number of boys and girls ; you have your children and try to do the best you can to be a good parent '' -LSB- 2 -RSB- . This attitude is probably not widely held , rather most women and their partners have some preferences in terms of the timing of births . This may be expressed in terms of age , marital status , or attainment of some educational , career , or economic goal . Despite this , a large percentage of pregnancies are unintended , including those that were experienced earlier than wanted -LRB- mistimed -RRB- or those that were not wanted at the time they occurred or at any future time -LRB- unwanted -RRB- . According to the 2002 NSFG , 30.8 % of all women 15 to 44 years of age had experienced an unintended birth at some time in their lives and , in the five years before the survey , 20.8 % had had a mistimed birth and 14.1 % an unwanted birth -LSB- 3 -RSB- . Using data from the 1982 , 1988 , and 1985 NSFGs , as well as abortion data , Henshaw estimated that in 1994 , 49.2 % of all pregnancies were unintended -LSB- 4 -RSB- . Employing a different set of questions to assess wantedness , the Pregnancy Risk Assessment Monitoring System -LRB- PRAMS -RRB- noted that in 1999 the percentage of unintended pregnancies resulting in live birth ranged from 33.7 % to 52 % across the 17 reporting states -LSB- 5 -RSB- . Although the relationship between use of a family planning method and pregnancy planning is sometimes tenuous - an analysis of the 1995 NSFG found that 30.9 % of the women who stated that their pregnancies had resulted from a contraceptive failure nevertheless classified the pregnancy as intended -LSB- 6 -RSB- . These data suggest that if preconception care were to be practiced widely , a larger percentage of women will need to seek family planning services to avoid unplanned pregnancies . Reasons for underutilization Many reasons have been suggested for the underutilization of family planning services , including cost , availability , and limited contraceptive methods -LSB- 7 , 8 -RSB- . Financial issues The possible patient payment sources for family planning services include private health insurance , Medicaid , or out-of-pocket payments . The March 2005 Current Population Survey found 24.5 % of women 18 to 20 years of age , 30.6 % of those 21 to 24 , 21.8 % of those 25 to 34 , and 17.1 % of those 35 to 44 to be uninsured -LSB- 9 -RSB- . If these uninsured women want to receive family planning services , they must rely on their own funds or seek care from facilities that provide services free of charge or on a sliding fee scale . These include publicly supported facilities such as health department family planning clinics , community health centers and public hospitals , and facilities that combine public and private funding sources , such as Planned Parenthood centers , women 's clinics , school-based health centers , and not-for-profit hospitals . Public funds for family planning services in such facilities come primarily from Medicaid and Title X -LRB- the family planning act -RRB- . These funds are inadequate to meet the need . For women whose eligibility is due to a pregnancy , eligibility for all medical services , including family planning , ends 60 days postpartum , except in states with a waiver to extend the period . Title X tries to fill in the gaps in coverage but it is chronically underfunded . Even for those with employer-based health insurance , coverage for family planning services is not universal . In 2003 , 93 % of health plans offered an annual ob/gyn visit , 88 % covered oral contraceptives ; 87 % , sterilization ; and 72 % , all five reversible contraceptives . HMOs were more likely to offer contraceptives and sterilization than conventional plans , PPOs or POSs -LSB- 10 -RSB- . Availability Family planning facilities need to be easily available both physically and psychologically . This means that they should be located where they can be reached easily by private or public transportation , be open days and hours that are convenient for potential users , offer the full range of contraceptive methods , provide educational materials in the languages of their patients , and employ personnel who can speak the language of the users and whose attitudes and behaviors are warm , friendly , and culturally sensitive . A recent four-state survey found that distance to a publicly financed family planning facility was not associated with teen or unintended pregnancies , suggesting that geographic availability is no longer a problem for family planning facilities -LSB- 11 -RSB- , although it still is for abortion services -LSB- 12 -RSB- . The same study found major differences in terms of the other availability factors , such as limited hours , few contraceptive choices , and lack of translators -LSB- 13 -RSB- . Such problems may be partially responsible for inadequate contraceptive use . Limited contraceptive methods Although the number of family planning methods has increased in the past few decades , many women and men have difficulty finding one with which they are comfortable . The 2002 NSFG gave respondents a list of 19 family planning methods from which to choose . Among women 15 -- 44 years of age , 61.9 % currently were using a contraceptive method : the pill-18.9 % ; female sterilization-16.7 % and the condom-11.1 % . About 4 % were using the least effective methods , including periodic abstinence and withdrawal . Among women who had intercourse in the three months before the interview and who were not sterile , pregnant , postpartum , or seeking pregnancy , 7.4 % were not using a contraceptive - an increase from the 5.2 % in the 1995 NSFG . -LRB- Of those at risk for an unintended pregnancy , 89.3 % were currently using a method . -RRB- -LSB- 1 -RSB- . It is important to recognize that contraceptive use data are based on self-reports and provide no indication of how consistently or correctly the methods are being used . Failure rates are high possibly because of inconsistent or improper use . In one study of the 1995 NSFG , 9 % of women experienced a contraceptive failure within one year of starting to use a reversible method of contraception : 7 % of those on the pill , 9 % of those relying on a male condom , and 19 % of those practicing withdrawal -LSB- 14 -RSB- . After female or male sterilization , hormonal methods are considered the most reliable form of contraception , but many women remain concerned about their safety . The side effects of many hormonal methods , especially Depo-Provera , discourage many women from their use -LSB- 7 , 8 -RSB- . Further , the need to take a pill daily even in the absence of frequent intercourse creates problems for many women . Finally , the absence of a male contraceptive other than sterilization and the condom is a major barrier to effective and ongoing contraception . The availability of one effective family planning method , emergency contraception -LRB- meant as back-up protection , not as a primary method -RRB- , is currently limited by the refusal of the federal Food and Drug Administration to allow it to be sold over the counter and by the refusal of some pharmacists to fill prescriptions for this medication . Inadequate attention to preconception counseling Research is just beginning on the availability of preconception care overall although certain conditions , such as folic acid supplementation and counseling of diabetic women , have been studied extensively . The little existing evidence suggests that preconception care is not routinely integrated into family planning services , whether provided by obstetricians or family medicine specialists in private practice or HMOs , or by personnel in family planning facilities -LSB- 15 , 16 -RSB- . Under such circumstances , the potential of this service delivery system for improving pregnancy and infant health through preconception care is not yet being realized . Approaches to increasing utilization Several evaluations indicate that the utilization of family planning services can be increased . California 's Family Planning , Access , Care , and Treatment Program -LRB- Family Pact -RRB- provided contraceptive services to low income , medically indigent women increased use and reduced the numbers of unintended pregnancies -LSB- 17 -RSB- . State family planning waivers that expand Medicaid coverage for women beyond the 60 day postpartum limit have had a similar impact -LSB- 18 , 19 -RSB- . Programs such as these should be expanded to more states , but they address only financial barriers . Attention should also be paid to other access-related problems , such as hours and days that facilities are open and language problems . Additional outreach also needs to be directed to low literacy and immigrant populations -LSB- 20 -RSB- . Approaches to improving content Moos -LSB- 15 -RSB- reviewed many of the activities that will be essential if preconception care is to be integrated into health care generally . The American College of Obstetrics and Gynecology recently published a Committee Opinion , `` The Important of Preconception Care in the Continuum of Women 's Heath Care '' -LSB- 21 -RSB- . Here the focus is on adding preconception counseling to visits for family planning . The recent publication by the Centers for Disease Control and Prevention of `` Recommendations to Improve Preconception Health and Health Care - United States '' -LSB- 22 -RSB- should also lead to more and better preconception counseling . In all likelihood , it may be most difficult to change patterns of family planning practice among physicians in private practice . In contrast , those in HMOs have the potential for exposure to more education about the need for such counseling . The establishment of standards for family planning services by the Health Plan Employer Data and Information Set -LRB- HEDIS -RRB- might also accelerate change . However , standard setting and financial and other incentives may be most effective when used with community health centers and health department and other publicly-funded sites of family planning services - as the women who use seek family planning at these sites may be those most in need of preconception care . Because such sites are funded by federal , state , and local governments , these units can insist that preconception care be integrated into their family planning services . Conclusions Progress towards preconception care for all women will only be possible if a larger percentage of women and men plan their pregnancies . At present , although visits for contraceptive advice and methods provide an excellent opportunity for counseling about ways to achieve healthy pregnancies and healthy infants through preconception care , this potential is not being achieved . Increased use of family planning and increased attention to preconception care within family planning services may require that additional resources be devoted to public and professional education and to service delivery standards and financing .

B I O O O O O O B I B I O O O O O O O O B I O O O O O O B I O O O O O O O O O B I O O B O O O O B I O O O O O O O O O O O O O O O B I O O O O O O B I O O O B I O O O O O O O O O O O B I O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O B I O O O O B I O O O O O O O O O O O O O O O O O O O O O O O B I O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O B I O O O O O O O O O O O O O B I O O O O O O O O B I O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O B I O O O O O B I O O O O O O O O B I O O O O B I O O O O O O O O O B I O O O O O O O B I O O O O O O O B I O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O B I O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O B O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O B I O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O B O O O O B I O O O O O O O O O O O O O O O O O B I O O O O O O O B I O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O B I O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O B I O O O O B I O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O B I O O O O B I O B I O O O O O O O O O O O O O O O O O O O O O

family planning
preconception care
pregnancy
access


Why

do

house-hunting

ants

recruit

in

both

directions

To

perform

tasks

organisms

often

use

multiple

procedures

Explaining

the

breadth

of

such

behavioural

repertoires

is

not

always

straightforward

During

house

hunting

colonies

of

Temnothorax

albipennis

ants

use

a

range

of

behaviours

to

organise

their

emigrations

In

particular

the

ants

use

tandem

running

to

recruit

naïve

ants

to

potential

nest

sites

Initially

they

use

forward

tandem

runs

-LRB-

FTRs

-RRB-

in

which

one

leader

takes

a

single

follower

along

the

route

from

the

old

nest

to

the

new

one

Later

they

use

reverse

tandem

runs

-LRB-

RTRs

-RRB-

in

the

opposite

direction

Tandem

runs

are

used

to

teach

active

ants

the

route

between

the

nests

so

that

they

can

be

involved

quickly

in

nest

evaluation

and

subsequent

recruitment

When

a

quorum

of

decision-makers

at

the

new

nest

is

reached

they

switch

to

carrying

nestmates

This

is

three

times

faster

than

tandem

running

As

a

rule

having

more

FTRs

early

should

thus

mean

faster

emigrations

thereby

reducing

the

colony

's

vulnerability

So

why

do

ants

use

RTRs

which

are

both

slow

and

late

It

would

seem

quicker

and

simpler

for

the

ants

to

use

more

FTRs

-LRB-

and

higher

quorums

-RRB-

to

have

enough

knowledgeable

ants

to

do

all

the

carrying

In

this

study

we

present

the

first

testable

theoretical

explanation

for

the

role

of

RTRs

We

set

out

to

find

the

theoretically

fastest

emigration

strategy

for

a

set

of

emigration

conditions

We

conclude

that

RTRs

can

have

a

positive

effect

on

emigration

speed

if

FTRs

are

limited

In

these

cases

low

quorums

together

with

lots

of

reverse

tandem

running

give

the

fastest

emigration

Introduction

Organisms

often

employ

more

than

one

mechanism

to

accomplish

a

task

For

instance

animals

typically

navigate

with

multiple

input

channels

The

classic

example

is

homing

by

the

rock

dove

Columba

livia

for

which

magnetic

fields

the

sun

landmarks

and

geophysical

processes

have

all

been

shown

to

be

used

-LRB-

Wiltschko

and

Wiltschko

-RRB-

The

range

of

behaviours

or

mechanisms

organisms

employ

may

be

puzzling

At

times

an

apparent

simplicity

is

observed

Defence

strategies

against

predators

are

a

well-studied

example

here

Acacia

trees

-LRB-

Acacia

spp.

-RRB-

either

have

chemical

defences

to

ward

off

herbivores

or

have

symbiotic

relationships

with

protective

ants

-LRB-

Rehr

et

al.

-RRB-

Hosts

parasitised

by

Eurasian

cuckoos

Cuculus

canorus

famously

reject

cuckoo

eggs

but

never

reject

cuckoo

chicks

-LRB-

Davies

-RRB-

This

simplicity

may

be

the

result

of

evolutionary

lag

but

more

interestingly

may

also

be

caused

by

one

strategy

making

another

maladaptive

by

reducing

predator

abundance

-LRB-

Planqué

et

al.

Britton

et

al.

-RRB-

Conversely

the

portfolio

of

behaviours

may

be

varied

and

complex

Different

mechanisms

may

complement

one

another

and

true

redundancy

is

often

hard

to

show

-LRB-

Able

and

Bingman

-RRB-

Indeed

the

existence

of

a

suite

of

mechanisms

against

a

broad

ensemble

of

predators

is

readily

understandable

One

exemplar

is

the

vertebrate

immune

system

-LRB-

Perelson

-RRB-

Another

striking

example

of

a

system

in

which

different

mechanisms

augment

and

complement

one

another

but

now

at

a

collective

level

is

house

hunting

in

social

insects

This

has

become

one

of

the

model

systems

to

study

distributed

decision

making

in

animals

When

the

nest

is

destroyed

the

colony

has

to

decide

collectively

where

to

settle

next

during

a

time

of

crisis

-LRB-

Franks

et

al.

-RRB-

Individual

ants

or

bees

have

been

shown

to

combine

sophisticated

assessments

of

potential

nest

sites

-LRB-

Seeley

Seeley

and

Morse

Mallon

and

Franks

Franks

et

al.

-RRB-

with

various

recruitment

mechanisms

to

collate

information

and

thus

make

collective

decisions

-LRB-

Mallon

et

al.

Pratt

et

al.

Pratt

Seeley

and

Visscher

Visscher

-RRB-

A

typical

emigration

by

a

colony

of

Temnothorax

albipennis

may

be

described

as

follows

When

the

old

nest

is

destroyed

a

fraction

of

ants

goes

out

scouting

to

find

a

new

home

Upon

finding

a

nest

the

nest

is

assessed

-LRB-

Mallon

and

Franks

-RRB-

and

ants

start

recruiting

other

ants

to

it

with

a

latency

that

is

inversely

proportional

to

the

perceived

nest

quality

-LRB-

Mallon

et

al.

-RRB-

using

a

process

called

forward

tandem

running

-LRB-

Möglich

et

al.

-RRB-

During

a

forward

tandem

run

a

knowledgeable

ant

teams

up

with

a

naïve

ant

The

leader

slowly

progresses

towards

the

new

nest

each

time

waiting

for

the

follower

to

catch

up

thereby

teaching

her

the

way

-LRB-

Franks

and

Richardson

-RRB-

Through

this

slow

recruitment

process

information

on

the

location

of

the

new

nest

spreads

and

recruiter

numbers

increase

Once

a

nest

population

reaches

a

certain

quorum

threshold

the

recruiters

switch

from

slow

tandem

running

to

much

faster

social

carrying

and

transport

the

remaining

passive

ants

and

brood

to

the

new

nests

-LRB-

Pratt

et

al.

Pratt

-RRB-

This

description

has

been

the

basis

of

several

models

-LRB-

Pratt

et

al.

Pratt

et

al.

Marshall

et

al.

Planqué

et

al.

-RRB-

However

a

behaviour

commonly

employed

by

these

ants

is

usually

not

included

-LRB-

but

see

Pratt

et

al.

-RRB-

and

has

never

been

analysed

After

the

quorum

recruiter

ants

are

not

only

engaged

in

social

carrying

but

also

regularly

perform

tandem

runs

from

the

new

back

to

the

old

nest

These

so-called

reverse

tandem

runs

-LRB-

Möglich

-RRB-

are

often

more

common

than

forward

tandem

runs

-LRB-

Mallon

et

al.

Pratt

et

al.

-RRB-

but

their

function

is

much

less

well

understood

To

maximise

fitness

the

colony

should

emigrate

as

quickly

as

possible

to

avoid

predation

and

other

hazards

Therefore

during

house

hunting

a

fast

build

up

of

recruiters

is

essential

Why

then

do

ants

mix

fast

carrying

with

slow

reverse

tandem

running

when

they

already

have

forward

tandem

running

at

their

disposal

In

this

paper

the

role

of

reverse

tandem

running

is

theoretically

investigated

In

particular

through

the

use

of

mathematical

models

we

explore

under

what

circumstances

reverse

tandem

running

can

have

a

positive

influence

on

emigration

speed

Materials

and

methods

We

present

two

mathematical

models

to

investigate

the

possible

role

of

reverse

tandem

runs

in

ant

colony

emigrations

Reverse

tandem

running

does

not

contribute

to

the

decision-making

process

of

which

new

nest

to

choose

-LRB-

Pratt

et

al.

Franks

et

al.

-RRB-

We

therefore

restrict

ourselves

to

emigrations

to

one

new

nest

only

We

model

the

emigration

as

follows

-LRB-

Fig.

-RRB-

Only

a

small

fraction

of

the

ants

in

a

colony

are

actively

involved

during

emigrations

-LRB-

Pratt

et

al.

Langridge

-RRB-

In

this

paper

we

thus

divide

the

colony

's

N

ants

into

fractions

FN

of

active

ants

A

and

-LRB-

F

-RRB-

N

passive

ants

P

This

assumption

to

divide

ants

into

active

and

passive

is

a

crucial

one

without

which

the

models

collapse

We

will

come

back

to

this

in

Discussion

Numbers

of

scouts

and

recruiters

are

denoted

S

and

R

respectively

The

rates

at

which

active

ants

leave

the

nest

and

become

scouts

and

scouts

recruiters

are

given

by

μ

and

k

respectively

Forward

tandem

running

occurs

at

a

rate

λ

until

the

quorum

Q

is

met

after

which

recruiters

carry

passive

ants

and

brood

at

a

rate

φ

To

incorporate

reverse

tandem

runs

we

need

to

model

which

ants

follow

these

tandem

runs

Available

data

from

nest-choice

experiments

-LRB-

Mallon

et

al.

-RRB-

suggest

two

possibilities

Either

the

reverse

tandem

runs

are

followed

by

ants

that

have

not

found

the

new

nest

yet

or

by

ants

that

have

been

carried

to

the

new

nest

These

two

options

are

not

necessarily

mutually

exclusive

the

carried

ants

could

have

been

scouts

We

modelled

both

these

two

possible

interpretations

Model

assumes

that

reverse

tandem

runs

are

followed

by

uncommitted

scouts

in

the

arena

and

model

assumes

they

are

followed

by

passive

ants

that

were

carried

to

the

new

nest

Fig.

of

the

two

different

models

for

which

reverse

tandem

runs

are

hypothesised

to

increase

speed

FTR

Recruitment

through

forward

tandem

running

RTR

recruitment

through

reverse

tandem

running

The

parameters

are

explained

in

Table

To

capture

in

detail

the

influence

of

reverse

tandem

runs

on

emigration

dynamics

we

need

to

consider

the

following

points

Both

tandem

running

and

social

carrying

involve

a

pair

of

ants

from

two

different

classes

Hence

recruitment

can

only

occur

if

ants

of

both

participating

classes

are

available

Once

the

quorum

has

been

met

recruiters

can

not

carry

and

perform

reverse

tandem

runs

simultaneously

-LRB-

we

also

assume

recruiters

are

not

involved

in

other

activities

than

these

two

-RRB-

The

interaction

between

different

classes

of

ants

has

been

modelled

using

simple

interaction

terms

We

assume

that

ants

of

both

classes

are

well

mixed

in

the

part

of

the

arena

-LRB-

or

nest

-RRB-

where

they

meet

With

populations

of

ants

of

size

X

and

Y

meeting

the

number

of

ants

that

on

average

meet

is

then

proportional

to

XY

-LRB-

X

Y

-RRB-

Importantly

the

smallest

class

limits

the

interaction

rate

as

is

to

be

expected

We

thus

also

have

to

specify

how

much

post-quorum

time

recruiters

spend

on

carrying

or

reverse

tandem

running

-LRB-

they

are

assumed

not

to

spend

any

time

on

other

behaviours

-RRB-

Before

the

quorum

is

met

the

rate

at

which

active

ants

at

the

old

nest

A

become

recruiters

R

through

tandem

running

is

given

by

λRA

-LRB-

A

R

-RRB-

Now

let

f

be

the

fraction

of

post-quorum

time

spent

on

reverse

tandem

runs

and

the

remainder

f

spent

on

social

carrying

Then

the

mean

number

of

scouts

becoming

recruiters

through

reverse

tandem

runs

is

For

carried

ants

becoming

recruiters

through

reverse

tandem

running

we

have

by

analogy

Similarly

the

mean

number

of

passive

ants

P

that

become

carried

ants

is

given

by

-LRB-

f

-RRB-

φRP

-LRB-

P

R

-RRB-

Recruiter

ants

should

not

perform

reverse

tandem

runs

when

there

are

no

scouts

or

carried

ants

left

Therefore

we

replace

f

by

in

Eqs

and

where

and

min

-LCB-

Cf

f

-RCB-

respectively

The

min

operation

is

for

computational

reasons

only

and

ensures

that

decreases

continuously

but

rapidly

to

zero

as

S

or

C

decreases

respectively

It

has

no

influence

on

the

models

predictions

We

drop

the

bar

on

in

the

rest

of

the

paper

Forward

tandem

running

only

occurs

before

the

quorum

is

met

and

carrying

and

reverse

tandem

running

only

after

These

are

modelled

with

functions

l

c

and

r

respectively

as

follows

and

setting

B

to

A

for

model

and

to

P

for

model

To

aid

the

reader

we

state

the

full

equations

for

both

models

The

equations

for

model

are

given

by

with

initial

conditions

-LRB-

A

S

R

P

C

-RRB-

-LRB-

-RRB-

-LRB-

FN

2ε

ε

ε

-LRB-

F

-RRB-

N

-RRB-

Model

is

specified

by

with

the

same

initial

conditions

as

model

Models

and

only

differ

in

the

placement

of

the

term

fr

-LRB-

λ

R

Q

C

-RRB-

In

both

models

the

ε

in

the

initial

conditions

is

necessary

to

avoid

singularities

in

the

denominators

of

the

interaction

functions

l

r

and

c

We

have

used

ε

throughout

We

also

explored

a

number

of

other

models

in

which

some

assumptions

were

relaxed

These

are

briefly

discussed

in

the

final

section

of

this

paper

The

main

hypothesis

we

tested

on

both

these

models

was

Reverse

tandem

runs

speed

up

the

emigration

if

recruiter

numbers

failed

to

increase

early

in

the

emigration

this

occurs

through

a

combination

of

the

new

nest

being

hard

to

find

and

forward

tandem

running

being

prohibited

We

tested

this

hypothesis

by

finding

the

fastest

emigration

strategy

for

given

parameter

settings

and

determining

whether

reverse

tandem

runs

formed

part

of

this

optimal

strategy

We

first

fixed

the

scouting

parameter

μ

the

fraction

of

active

ants

at

the

old

nest

F

and

k

the

rate

at

which

scouts

become

recruiters

Then

quorum

size

Q

and

fraction

of

post-quorum

reverse

tandem

running

time

f

were

varied

to

optimise

emigration

speed

Individual

runs

were

performed

in

Matlab

using

a

standard

solver

Emigrations

were

termed

completed

when

all

passive

ants

and

active

ants

at

the

old

nest

had

disappeared

In

particular

we

set

the

threshold

for

emigration

completeness

at

P

A

Optimal

strategies

were

found

using

the

Nelder

Mead

simplex

method

-LRB-

Nelder

and

Mead

-RRB-

Parameters

μ

and

F

were

varied

on

an

equidistant

grid

spanning

-LSB-

-RSB-

-LSB-

-RSB-

Recruitment

latency

k

was

set

at

either

or

The

ranges

of

these

parameters

are

inspired

by

experimental

estimates

in

-LRB-

Pratt

et

al.

Pratt

-RRB-

Parameter

values

are

summerised

in

Table

Table

or

ranges

where

applicable

for

the

parameters

used

in

models

and

depicted

in

Fig.

of

active

ants

-LSB-

-RSB-

QQuorum

thresholdn.a.fFraction

of

post-quorum

reverse

tandem

running

timen.a.μRate

at

which

active

ants

at

old

nest

become

scouts

-LRB-

ant

min

-RRB-

-LSB-

-RSB-

λRate

at

which

ants

following

tandem

runs

become

recruiters

-LRB-

ant

min

-RRB-

φRate

at

which

passive

ants

are

carried

to

new

nest

-LRB-

ant

min

-RRB-

kRate

at

which

scouts

independently

become

recruiters

-LRB-

ant

min

-RRB-

-LCB-

-RCB-

Parameter

choices

for

λ

φ

and

N

were

taken

from

the

ranges

in

Pratt

et

al.

-LRB-

-RRB-

Results

For

both

models

the

optimal

emigration

strategy

included

reverse

tandem

runs

for

a

wide

range

of

parameters

together

with

low

quorum

thresholds

-LRB-

Fig.

-RRB-

Fixing

k

whilst

varying

μ

and

F

the

optimal

strategy

often

contained

more

reverse

than

forward

tandem

runs

for

a

large

part

of

the

parameter

range

-LRB-

Fig.

-RRB-

The

fraction

of

time

spent

on

reverse

tandem

running

f

and

the

quorum

threshold

Q

were

negatively

correlated

When

either

the

fraction

of

active

ants

F

decreased

or

the

scouting

parameter

μ

increased

fraction

f

increased

and

the

quorum

Q

decreased

Choosing

a

higher

recruitment

latency

by

decreasing

k

gave

more

reverse

tandem

running

and

lower

quorum

thresholds

-LRB-

Fig.

-RRB-

Fig.

fractions

of

post-quorum

time

spent

on

reverse

tandem

runs

-LRB-

top

figures

-RRB-

and

optimal

quorum

thresholds

-LRB-

bottom

figures

-RRB-

for

models

-LRB-

left

two

columns

-RRB-

and

-LRB-

right

two

columns

-RRB-

for

varying

fractions

of

active

ants

F

and

scouting

probabilities

μ

and

for

two

values

of

recruitment

latencies

k

Other

parameter

values

used

are

given

in

Table

See

text

for

simulation

details

For

both

values

of

k

reverse

tandem

runs

are

part

of

the

optimal

emigration

strategy

when

scouting

probability

is

high

or

when

fraction

of

active

ants

is

low

Lowering

k

enhances

the

use

of

reverse

tandem

running

Note

that

although

models

and

broadly

give

similar

predictions

they

differ

in

the

amount

of

post-quorum

time

spent

on

reverse

tandem

runs

In

model

this

reaches

a

full

in

model

but

never

so

in

model

Overall

the

models

predict

that

reverse

tandem

running

should

be

used

more

than

forward

tandem

running

and

the

quorum

threshold

lowered

if

the

recruitment

latency

increases

by

decreasing

k

-LRB-

scouting

ants

wait

longer

before

starting

their

first

recruitment

act

-RRB-

in

combination

with

either

a

decreasing

fraction

of

active

ants

F

or

an

increasing

scouting

parameter

μ

For

all

but

very

large

F

the

optimal

quorum

threshold

corresponded

to

the

time

when

all

active

ants

have

left

the

old

nest

to

go

scouting

In

the

absence

of

multiple

new

nests

the

decision

when

to

switch

from

forward

tandem

running

to

social

carrying

is

thus

best

made

at

the

old

nest

Recruiters

should

thus

apply

the

following

rule

Continue

forward

tandem

running

until

there

are

no

ants

left

to

perform

them

with

and

then

switch

to

social

carrying

if

few

forward

tandem

runs

have

been

performed

-LRB-

by

the

recruiters

-RRB-

combine

carrying

with

reverse

tandem

runs

otherwise

do

not

The

numbers

of

forward

tandem

runs

reverse

tandem

runs

the

numbers

of

carried

ants

in

the

new

nest

and

total

emigration

time

were

computed

for

each

of

the

optimal

strategies

of

models

and

-LRB-

Fig.

-RRB-

We

note

four

points

First

for

a

large

parameter

range

there

are

more

reverse

tandem

runs

than

forward

tandem

runs

This

is

broadly

consistent

with

the

experimental

data

from

nest

choice

experiments

in

Mallon

et

al.

-LRB-

-RRB-

Numbers

there

range

between

and

forward

tandems

and

between

and

reverse

tandems

and

reverse

tandems

were

always

performed

more

often

than

forward

tandems

Second

as

a

validation

of

our

optimisation

method

note

that

the

optimal

emigration

time

varies

smoothly

under

parameter

changes

as

is

to

be

expected

for

this

type

of

model

Third

for

model

despite

a

clear

drop

in

the

post-quorum

time

spent

on

reverse

tandem

runs

with

increasing

F

-LRB-

see

Fig.

top

left

-RRB-

the

number

of

reverse

tandem

runs

in

fact

varies

smoothly

Fourth

the

number

of

carried

ants

that

remained

in

the

nest

at

the

end

of

the

emigration

is

clearly

different

between

models

and

In

model

this

number

is

just

-LRB-

F

-RRB-

N

the

number

of

passive

ants

in

the

colony

In

model

however

over

half

of

the

colony

may

end

up

being

recruiters

by

drawing

recruits

from

the

carried

class

using

reverse

tandem

runs

Fig.

of

forward

and

reverse

tandem

runs

number

of

carried

ants

and

emigration

time

computed

for

each

of

the

optimal

strategies

for

models

-LRB-

top

row

-RRB-

and

-LRB-

bottom

row

-RRB-

illustrated

in

Fig.

See

that

figure

for

details

and

parameter

choices

Here

we

have

only

illustrated

k

Discussion

To

maximise

their

fitness

ants

should

try

to

achieve

the

fastest

emigrations

to

minimise

vulnerability

-LRB-

Franks

et

al.

Franks

et

al.

-RRB-

Therefore

the

active

ants

either

have

to

become

scouts

discover

a

new

site

and

then

become

recruiters

or

wait

at

the

old

nest

until

a

recruiter

leads

them

to

the

new

nest

Both

of

these

processes

may

be

hampered

When

all

the

active

ants

go

out

scouting

recruiter

numbers

slowly

increase

if

the

new

nest

is

hard

to

find

or

if

those

few

can

not

find

any

active

ant

back

at

the

old

nest

to

tandem

run

with

In

terms

of

the

models

this

could

occur

if

scouts

slowly

become

recruiters

-LRB-

low

value

for

k

-RRB-

in

combination

with

either

a

small

class

of

active

ants

at

the

old

nest

-LRB-

F

is

small

-RRB-

or

all

active

ants

having

gone

scouting

-LRB-

high

value

for

scouting

rate

μ

-RRB-

Under

either

or

both

of

these

circumstances

the

model

predicts

that

ants

should

not

waste

time

trying

to

recruit

by

forward

tandem

runs

but

should

do

the

next

best

thing

and

use

a

low

quorum

threshold

to

quickly

switch

to

carrying

The

recruiters

should

then

invest

a

fraction

of

their

time

to

recruit

scouts

or

carried

ants

using

reverse

tandem

runs

thus

boosting

the

recruiter

population

and

speeding

up

the

emigration

Conversely

the

model

also

predicts

that

reverse

tandem

runs

should

not

be

used

if

either

the

new

nest

is

easy

to

find

-LRB-

recruiter

numbers

then

build

quickly

anyway

-RRB-

or

when

there

are

many

ants

to

follow

a

forward

tandem

run

These

predictions

fit

quite

well

with

previous

experimental

work

Ants

have

been

shown

to

leave

their

intact

old

nest

if

the

new

nest

is

sufficiently

better

but

have

lower

standards

when

their

nest

is

destroyed

-LRB-

Dornhaus

et

al.

-RRB-

In

these

experiments

reverse

tandem

runs

were

mainly

observed

when

the

old

nest

was

destroyed

combined

with

few

forward

tandem

runs

The

model

offers

a

simple

explanation

for

this

The

greater

panic

might

have

caused

fewer

scouts

to

remain

at

the

old

nest

thereby

obstructing

early

recruitment

Whilst

investigating

speed

accuracy

trade-offs

Franks

et

al.

-LRB-

-RRB-

found

lower

quorums

under

harsh

than

under

mild

conditions

This

again

fits

with

the

models

On

the

other

hand

the

models

also

predict

higher

numbers

of

reverse

tandem

runs

In

the

experiments

this

difference

in

reverse

tandem

running

activity

between

mild

and

harsher

conditions

was

found

to

be

non-significant

-LRB-

Franks

et

al.

-RRB-

Critique

on

model

Although

evidence

for

which

ants

follow

reverse

tandem

runs

is

scarce

both

models

give

the

same

qualitative

predictions

Note

however

that

the

dynamics

of

the

different

ant

classes

during

a

simulated

emigration

in

model

poorly

match

observed

experimental

dynamics

-LRB-

see

e.g.

Planqué

et

al.

-RRB-

In

many

cases

the

final

number

of

ants

active

in

an

emigration

is

much

greater

than

the

original

number

of

active

ants

An

example

is

given

in

Fig.

These

recruiter

numbers

far

exceed

observed

numbers

of

active

ants

-LRB-

available

in

Table

in

Pratt

et

al.

-RRB-

Indeed

simulated

emigrations

often

end

with

half

the

colony

being

recruiters

and

less

than

half

carried

into

the

new

nest

-LRB-

Fig.

bottom

row

third

from

left

-RRB-

Fig.

of

temporal

dynamics

for

models

and

At

μ

F

we

have

taken

parameters

optimal

for

models

and

respectively

Notice

that

in

model

the

number

of

recruiters

rises

to

about

but

in

model

there

are

no

less

than

recruiters

at

the

end

of

the

emigration

indicating

that

recruitment

from

the

carried

class

-LRB-

model

-RRB-

may

give

rise

to

very

unrealistic

emigration

dynamics

Reverse

tandem

activity

Figure

-LRB-

top

left

-RRB-

shows

that

recruiters

in

model

should

use

a

sequential

strategy

if

F

is

small

-LRB-

and

μ

is

large

-RRB-

When

the

quorum

is

met

they

first

spend

all

of

their

time

on

reverse

tandem

runs

until

all

scouts

have

become

recruiters

and

then

switch

to

carrying

In

contrast

when

F

is

large

recruiters

mix

tandem

running

and

carrying

This

qualitative

difference

may

be

understood

as

follows

The

total

number

of

recruiters

is

bounded

by

FN

the

number

of

active

ants

in

the

colony

As

F

decreases

the

remaining

recruiters

take

longer

to

carry

all

the

passive

ants

Hence

the

time

costs

for

not

having

the

recruiters

increases

and

the

time

to

recruit

the

remaining

scouts

decreases

-LRB-

as

there

are

fewer

scouts

too

-RRB-

Hence

in

this

situation

recruiters

should

devote

their

post-quorum

time

first

all

on

reverse

tandem

running

before

starting

carrying

When

F

is

large

the

reverse

argument

applies

With

less

passive

ants

there

should

be

less

emphasis

on

additional

recruitment

by

reverse

tandem

running

One

does

not

have

to

make

many

hands

if

the

work

was

light

to

start

with

Note

that

this

behaviour

for

F

is

different

for

model

In

this

paper

we

never

observe

sequential

strategies

-LRB-

Fig.

top

right

-RRB-

as

there

is

no

end

to

building

recruiter

numbers

but

by

completing

the

entire

emigration

This

argument

also

explains

another

difference

between

these

models

The

number

of

reverse

tandem

runs

during

an

emigration

In

model

there

is

a

clear

maximum

for

intermediate

F

whereas

in

model

the

number

of

reverse

tandems

strictly

decreases

with

F

-LRB-

Fig.

second

from

left

top

and

bottom

-RRB-

Nonlinearities

in

the

models

and

divisions

between

active

and

passive

ants

Contrary

to

the

models

in

this

paper

two

previous

models

of

house

hunting

by

T.

albipennis

ants

-LRB-

Pratt

et

al.

Planqué

et

al.

-RRB-

assumed

linear

terms

for

tandem

running

and

social

carrying

There

these

processes

occurred

at

rates

only

proportional

to

the

number

of

recruiters

The

predictions

of

the

current

models

proved

to

be

strongly

dependent

on

the

assumption

of

non-linearity

of

these

terms

The

corresponding

linear

models

predicted

that

reverse

tandem

running

should

not

be

used

for

practically

any

parameter

choices

in

F

and

μ

or

k.

Another

ingredient

in

this

model

shared

with

the

previous

-LRB-

Pratt

et

al.

Planqué

et

al.

-RRB-

models

of

this

collective

decision-making

system

is

the

division

between

active

and

passive

ants

There

is

as

yet

little

experimental

evidence

suggesting

this

division

really

exists

All

we

know

at

present

is

that

a

limited

fraction

of

ants

is

actively

engaged

during

an

emigration

We

have

thus

also

explored

models

in

which

this

division

was

absent

using

both

linear

and

non-linear

interaction

terms

such

as

those

in

models

and

presented

in

this

paper

In

of

these

models

did

reverse

tandem

running

contribute

to

the

optimal

emigration

speed

The

division

between

active

and

passive

ants

is

thus

a

crucial

ingredient

for

reverse

tandem

running

to

have

a

positive

impact

on

emigration

speed

which

should

be

experimentally

validated

Hypothesised

explanations

Several

hypotheses

on

the

potential

role

of

reverse

tandem

running

have

been

put

forward

-LRB-

Pratt

et

al.

-RRB-

First

the

ants

might

have

a

home

nest

which

changes

during

the

emigration

thereby

reversing

the

direction

of

any

recruitment

events

from

home

to

another

nest

-LRB-

Pratt

et

al.

-RRB-

If

true

this

would

predict

a

change

of

direction

when

about

half

of

the

colony

had

been

displaced

This

is

not

in

agreement

with

the

available

data

-LRB-

Mallon

et

al.

-RRB-

Moreover

this

hypothesis

does

not

offer

a

suggestion

why

tandem

running

often

occurs

early

in

the

emigration

In

other

words

it

might

explain

the

direction

but

not

the

occurrence

itself

Second

it

has

been

suggested

that

reverse

tandem

running

may

re-allocate

recruitment

-LRB-

Pratt

et

al.

-RRB-

Again

this

does

not

fit

the

available

data

from

Mallon

et

al.

-LRB-

-RRB-

Reverse

tandem

runs

were

nearly

always

observed

between

the

best

nest

and

the

old

nest

The

models

in

this

paper

do

not

incorporate

choice

between

nest

sites

but

we

conjecture

that

early

flexible

commitment

-LRB-

Planqué

et

al.

-RRB-

will

be

more

efficient

in

redirecting

ants

to

better

nests

than

late

recruitment

Other

experimental

results

also

corroborate

that

reverse

tandem

running

does

not

influence

the

decision-making

process

-LRB-

Franks

et

al.

-RRB-

The

first

models

in

which

reverse

tandem

runs

have

been

explicitly

incorporated

to

analyse

their

role

have

yielded

clear

predictions

under

a

range

of

conditions

we

expect

a

negative

correlation

between

levels

of

early

and

late

recruitment

This

finding

lends

itself

well

to

simple

experiments

and

we

aim

to

present

those

in

the

near

future

The

build

up

of

recruiter

numbers

serves

two

purposes

to

decide

on

a

nest

and

to

increase

the

number

of

ants

actively

involved

in

transport

The

decision-making

process

and

the

implementation

of

this

decision

are

thus

conflated

This

in

itself

is

a

side-effect

of

the

distributed

nature

of

this

system

Reverse

tandem

running

may

thus

be

a

logical

extension

to

overcome

this

inherent

problem

This

suggests

that

such

additional

backup

behaviours

could

be

a

common

feature

of

decentralised

collective

decision-making

systems

O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O B I O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O

social insects
tandem running
temnothorax albipennis

recruitment methods
collective behaviour